DanG144
Top Post Dawg
What was your low pressure - it is the same as the high pressure with the AC clutch not working. And it should be pretty high.
Dan
Dan
AC doesn't work
- Thread starter Sergey
- Start date
DanG144
Top Post Dawg
Look in post #21, the top photo. It is hanging upside down under the battery. It is called the fan control module.aladin61 said:
Dan
aladin61
Member
- Joined
- Oct 16, 2008
- Location
- Murrieta, CA
- TDI
- 1999.5 Jetta, 1997 Ford F350, 2005 Jeep CRD, 2003 VW Golf TDI, 2002 Jetta wagon TDI
The low pressure is just above 75 psi.
Last edited:
aladin61
Member
- Joined
- Oct 16, 2008
- Location
- Murrieta, CA
- TDI
- 1999.5 Jetta, 1997 Ford F350, 2005 Jeep CRD, 2003 VW Golf TDI, 2002 Jetta wagon TDI
I found this procedure, will it work for the TDI I have?
How to Diagnose A/C System On 2000 VW Jetta GLS
[SIZE=-2]Posted 11/16/2005[/SIZE]
[SIZE=-1]By Jim Newkirk
[SIZE=-1]“ The problem involved a 2000 Jetta GLS 2.8L manual A/C system with no compressor clutch operation. On this vehicle, the cooling fan and A/C compressor operation are controlled by the J293 fan control module, which is usually located in the driver's front corner of the engine compartment on the lower frame rail. The J293 module has both a 14-pin connector identified as the T14 connector in Volkswagen wiring diagrams and a four-pin connector identified as the T4a connector. ”[/SIZE]
This summer has been a hot one, and I'm sure you have seen your share of air conditioning problems. Unfortunately, A/C systems have grown steadily more complex and difficult to diagnose.
The problem involved a 2000 Jetta GLS 2.8L manual A/C system with no compressor clutch operation. On this vehicle, the cooling fan and A/C compressor operation are controlled by the J293 fan control module, which is usually located in the driver's front corner of the engine compartment on the lower frame rail. The J293 module has both a 14-pin connector identified as the T14 connector in Volkswagen wiring diagrams and a four-pin connector identified as the T4a connector.
To diagnose this system, starting on the T14 connector:
1) Start and idle the vehicle. Select "A/C on" at maximum cooling and "blower on" at high speed.
2) Check for 12 volts at the T14 connector pin No. 8 (T14/8). This 12-volt signal comes from the A/C switch and requires both cooling fans on at low speed and compressor activation.
3) Check for 12 volts at pin T14/9. This voltage is a switched ignition source and will have 12 volts when the ignition is in the "on" position.
4) Check for 12 volts at pin T14/4. This is a constant battery source and should read 12 volts at all times from fuse S16.
5) Check for a good ground at pin T14/6.
6) Check for 12 volts at all times at the four-pin connector, T4a pins T4a/1 and T4a/3 from fuses S164 and S180, respectively.
7) Turn off the ignition. Remove the T14 connector and check for continuity between pins T14/14 and T14/5 on harness side to ensure proper operation of the F38 ambient temperature switch. Continuity must be present if the ambient air temperature is above 32 degrees Fahrenheit. Reconnect the T14 connector and restart the vehicle.
8) Check pin T14/2 using a duty cycle meter. If the refrigerant charge in the system is normal, about 30 percent to 35 percent duty should be indicated at pin T14/2 without the compressor engaged. The duty cycle signal is supplied by the G65 pressure sensor in response to system pressure changes. A duty cycle above 90 percent or below 20 percent will command the compressor off.
9) Check for an 11-volt reference voltage at pin T14/3. The reference voltage originates in the J293 fan control module and can be grounded by |the power control module (PCM) under certain circumstances (typically wide open throttle or vehicle overheat conditions) to turn the A/C compressor off.
If zero volts are present, the PCM is commanding "compressor off" or the wiring harness is shorted to ground. Raise vehicle idle speed above 2500 rpm and observe compressor operation and voltage at pin T14/3. If the voltage at pin T14/3 returns to 11 volts with the idle speed above 2500 rpm and compressor operation resumes, then a throttle basic setting procedure is needed and must be performed with a factory-compatible, by-directional scan tool. Note: A loss of throttle basic settings will keep the compressor from activating.
If all previous tests have passed, check the T14 connector pin T14/10 for 12 volts. This pin is the output signal to the compressor clutch coil. If all the other tests have passed and there is no voltage at pin T14/10, this indicates a faulty fan control module. As you can see, turning on an A/C clutch is not a simple function on late model vehicles, and systems that you might not associate with an A/C problem can stop you and your customer from keeping cool. Be sure to check Direct-Hit's Hotline Archive section for more diagnostic procedures and tips.
[/SIZE]
How to Diagnose A/C System On 2000 VW Jetta GLS
[SIZE=-2]Posted 11/16/2005[/SIZE]
[SIZE=-1]By Jim Newkirk
[SIZE=-1]“ The problem involved a 2000 Jetta GLS 2.8L manual A/C system with no compressor clutch operation. On this vehicle, the cooling fan and A/C compressor operation are controlled by the J293 fan control module, which is usually located in the driver's front corner of the engine compartment on the lower frame rail. The J293 module has both a 14-pin connector identified as the T14 connector in Volkswagen wiring diagrams and a four-pin connector identified as the T4a connector. ”[/SIZE]
This summer has been a hot one, and I'm sure you have seen your share of air conditioning problems. Unfortunately, A/C systems have grown steadily more complex and difficult to diagnose.
The problem involved a 2000 Jetta GLS 2.8L manual A/C system with no compressor clutch operation. On this vehicle, the cooling fan and A/C compressor operation are controlled by the J293 fan control module, which is usually located in the driver's front corner of the engine compartment on the lower frame rail. The J293 module has both a 14-pin connector identified as the T14 connector in Volkswagen wiring diagrams and a four-pin connector identified as the T4a connector.
To diagnose this system, starting on the T14 connector:
1) Start and idle the vehicle. Select "A/C on" at maximum cooling and "blower on" at high speed.
2) Check for 12 volts at the T14 connector pin No. 8 (T14/8). This 12-volt signal comes from the A/C switch and requires both cooling fans on at low speed and compressor activation.
3) Check for 12 volts at pin T14/9. This voltage is a switched ignition source and will have 12 volts when the ignition is in the "on" position.
4) Check for 12 volts at pin T14/4. This is a constant battery source and should read 12 volts at all times from fuse S16.
5) Check for a good ground at pin T14/6.
6) Check for 12 volts at all times at the four-pin connector, T4a pins T4a/1 and T4a/3 from fuses S164 and S180, respectively.
7) Turn off the ignition. Remove the T14 connector and check for continuity between pins T14/14 and T14/5 on harness side to ensure proper operation of the F38 ambient temperature switch. Continuity must be present if the ambient air temperature is above 32 degrees Fahrenheit. Reconnect the T14 connector and restart the vehicle.
8) Check pin T14/2 using a duty cycle meter. If the refrigerant charge in the system is normal, about 30 percent to 35 percent duty should be indicated at pin T14/2 without the compressor engaged. The duty cycle signal is supplied by the G65 pressure sensor in response to system pressure changes. A duty cycle above 90 percent or below 20 percent will command the compressor off.
9) Check for an 11-volt reference voltage at pin T14/3. The reference voltage originates in the J293 fan control module and can be grounded by |the power control module (PCM) under certain circumstances (typically wide open throttle or vehicle overheat conditions) to turn the A/C compressor off.
If zero volts are present, the PCM is commanding "compressor off" or the wiring harness is shorted to ground. Raise vehicle idle speed above 2500 rpm and observe compressor operation and voltage at pin T14/3. If the voltage at pin T14/3 returns to 11 volts with the idle speed above 2500 rpm and compressor operation resumes, then a throttle basic setting procedure is needed and must be performed with a factory-compatible, by-directional scan tool. Note: A loss of throttle basic settings will keep the compressor from activating.
If all previous tests have passed, check the T14 connector pin T14/10 for 12 volts. This pin is the output signal to the compressor clutch coil. If all the other tests have passed and there is no voltage at pin T14/10, this indicates a faulty fan control module. As you can see, turning on an A/C clutch is not a simple function on late model vehicles, and systems that you might not associate with an A/C problem can stop you and your customer from keeping cool. Be sure to check Direct-Hit's Hotline Archive section for more diagnostic procedures and tips.
[/SIZE]
DanG144
Top Post Dawg
If your car was built from September of 1998 to May of 1999, then this will not work for you. You have a 10 pin connector instead of a 14 pin connector. If it was built after May of 1999, then this would work for you.
I have been assuming that yours was one of the early ones. You can tell by the component used for the "high pressure detector", if it has a dumb 4 pin switch, then you have the early system. If it has a 3pin G65 it is the new system.
Dan
I have been assuming that yours was one of the early ones. You can tell by the component used for the "high pressure detector", if it has a dumb 4 pin switch, then you have the early system. If it has a 3pin G65 it is the new system.
Dan
aladin61 said:
DanG144
Top Post Dawg
That is good for about 70 degrees or so.aladin61 said:
aladin61
Member
- Joined
- Oct 16, 2008
- Location
- Murrieta, CA
- TDI
- 1999.5 Jetta, 1997 Ford F350, 2005 Jeep CRD, 2003 VW Golf TDI, 2002 Jetta wagon TDI
The MFR date is 2/1999, So I must have the old one.
DanG144
Top Post Dawg
After you have checked the pressure switch, and all the fuses, and measured your clutch resistance, if you still have not found the problem, I will alter the troubleshooting guide to cover your model and post it. I may not be able to do it until Sunday...depends.
Just be warned... that area is a real bear to get to with the battery and it's holder in place, (it might be tough even with it out!) and if the battery is not in place you have to make some provision to jumper power to the car to do the tests. You would probably be better off to get it up on stands and pull the belly pan off.
PM me if you don't see it by Sunday evening. I might need my elbow jogged.
Dan
Just be warned... that area is a real bear to get to with the battery and it's holder in place, (it might be tough even with it out!) and if the battery is not in place you have to make some provision to jumper power to the car to do the tests. You would probably be better off to get it up on stands and pull the belly pan off.
PM me if you don't see it by Sunday evening. I might need my elbow jogged.
Dan
DanG144
Top Post Dawg
Air conditioning troubleshooting plan for Sept 98 to May 1999 A/C
Original Posted 11/16/2005
By Jim Newkirk
adapted for TDI’s from September 2008 to May 1999 by Dan Goldston in October of 2008. Comments and new steps were added. No one has checked my work, here, so use this with caution. Don’t make expensive decisions without checking with another source, Dan.
“ The problem involved a 1999.5 Jetta TDI ALH manual A/C system with no compressor clutch operation. On this vehicle, the cooling fan and A/C compressor operation are controlled by the J293 fan control module, which is usually located in the driver's front corner of the engine compartment on the lower frame rail. The J293 module has both a 10-pin connector identified as the T10b connector in Volkswagen wiring diagrams and a four-pin connector identified as the T4a connector. ”
This summer has been a hot one, and I'm sure you have seen your share of air conditioning problems. Unfortunately, A/C systems have grown steadily more complex and difficult to diagnose.
The problem involved a 1999.5 Jetta ALH TDI manual A/C system with no compressor clutch operation. On this vehicle, the cooling fan and A/C compressor operation are controlled by the J293 fan control module, which is usually located in the left front corner of the engine compartment on the lower frame rail, sort of under the battery. The J293 module has both a 10-pin connector identified as the T10b connector in Volkswagen wiring diagrams and a four-pin connector identified as the T4a connector.
Before you really get started:
Check fuses 5, 25, and 16 on the fuse panel inside the cabin. Verify voltage on both sides.
Check fuses S164 and S180 on top of the battery. Verify voltage on both sides.
Bentley section 14 of the wiring diagrams, pages 97-152 to 97-156, is an excellent reference.
Never check continuity (ohms) on a circuit that has power to it. You’ll get bad readings and/or destroy your meter. Continuity for our purposes here, where we are checking switches and wires, means 0, zero, ohms.
Section A.
To diagnose this system, starting on the T10 connector:
1) Start and idle the vehicle. Select "A/C on" at maximum cooling and "blower on" at high speed (high speed just keeps the compressor loaded, signal development is the same for any speed).
1a) First check for 12 volts at pin 1 of N25, the AC clutch connector, if voltage is not present go to step 2.
1b) if 12 volts is present on Pin 1 of N25, then check for continuity to ground at pin 2 of the AC clutch connector.
1c) If these are both good, check for continuity through the clutch coil. It must be bad.
2) Check for 12 volts at the T10a connector pin No. 8 and 5 (T10b/8, T10b/5). This 12-volt signal comes from the A/C switch and requests both cooling fans on at low speed and compressor activation by the Fan Control Module. (Through fuse 25, the fresh air blower switch, the AC switch, F129 pressure switch , F38 ambient temperature switch, and F163 A/C high temperature cutout switch. This signal is also sent to the ECM, Engine Control Module.) If this voltage is not present, drop down to section B.
3) If you had voltage on T10b/8, and T10b/5, Check for 12 volts at pin T10b/9. This voltage is a switched ignition source and will have 12 volts when the ignition is in the "on" position.(Through fuse 5.)
4) Check for 12 volts at pin T10b/4. This is a constant battery source and should read 12 volts at all times from fuse S16.
5) Check for a good ground at pin T10b/6.
6) Check for 12 volts at all times at the four-pin connector, T4a pins T4a/4 and T4a/3 from fuses S164 and S180, respectively.
7) Check for an 11-volt reference voltage at pin T10/3. The reference voltage originates in the J293 fan control module and can be grounded by the control module (ECM) under certain circumstances (typically wide open throttle or vehicle overheat conditions) to turn the A/C compressor off.
7a)If zero volts are present, the PCM is commanding "compressor off" or the wiring harness is shorted to ground. Raise vehicle idle speed above 2500 rpm and observe compressor operation and voltage at pin T10b/3. If the voltage at pin T10b/3 returns to 11 volts with the idle speed above 2500 rpm and compressor operation resumes, then a throttle basic setting procedure is needed and must be performed with a factory-compatible, by-directional scan tool. Note: A loss of throttle basic settings will keep the compressor from activating. (I just left this section in from the 2000 and on version…I have no idea if this is the case for the early version of the vehicle or not, DanG144.)
8) If all previous tests have passed, check the T10b connector pin T10b/10 for 12 volts. This pin is the output signal to the compressor clutch coil. If all the other tests have passed and there is no voltage at pin T10b/10, this indicates a faulty fan control module. As you can see, turning on an A/C clutch is not a simple function on late model vehicles, and systems that you might not associate with an A/C problem can stop you and your customer from keeping cool. Be sure to check Direct-Hit's Hotline Archive section for more diagnostic procedures and tips.
Section B (from section A step 2)
If 12 volts is not present on T10b/8 and T10B/5 you need to find out why - and there can be many reasons.
1) Verify Fuse 25 is good, with voltage on both sides. Make sure.
2) Check the halfway point. Verify 12 volts are present on Pin 2 (blue and red wire) of the F129 connector (pressure switch located in A/C line near firewall and expansion valve. If not go to step 8, the problem is in the first half of the circuit.
3) So you had 12 volts on F129 pin 2, verify continuity from pins 1 to 2 on F129, and reinstall the connector. You should definitely have continuity if the A/C pressures are between 1.2 and 24 bar (17.4 and 348 psig). [The high pressure switch opens at 32 bar (464psig) and closes back at 24 bar (348 psig), so it is sometimes closed between these pressures and sometimes open] If continuity is good, reinstall the connector. If bad, check the pressures. If pressures are good and continuity is bad, you have a bad pressure switch.
4) If everything checks out so far, check 12 volts present at pin 2 of F38, the Ambient Temperature Switch. If not, your wiring must be bad from F129 to F38. If 12 volts is present at pin 2, check the continuity of F38. This switch should have 0 ohms if temperature is above 45 degrees F. (it opens at 30F, closes at 45 F). Reinstall the connector.
5) If everything checks out so far, check 12 volts at pin 1 of F163, the A/C thermal cutout switch. If 12 volts is not present, the wiring must be bad between F38 and F163. If 12 volts is present, check the continuity of F163. F163 should be closed (0 ohms, have continuity) unless the A/C temperature is greater than 234 F (opens at 246F, closes at 234 F.)
6) If everything is good so far, follow the green wire off of pin 2 of F163 until you find a junction - L10 – named “wire connection-2- in A/C wiring harness” the green wire is headed for pins T10b/8 and T10b/5. No further clues as to location. At this junction wires will connect from the three terminals mentioned (and PM Dang144 with the location, pictures would be good). Theoretically the car is still running with the A/C on and a fan speed selected, so be careful to not short these wires to ground. (More likely, after you locate this connection, turn the car and A/C back on to check the voltage. Have the car off if you disassemble and clean this connection.)
7) There is nothing left but wire to pins T10b/8 and T10b/5. IF the problem was in the second half of the circuit, you should have found it.
8) If the voltage in step B2 was bad at pin 2 of F129 the problem must be in the first half of the circuit. Check for 12 volts at pin T8b/1, the 8 pin connector on the A/C switch. If 12 volts is present then the problem must be in the wiring between these two components, which includes L9 “wire connection-1-in A/C wiring harness (pm DanG144 with location and pics) and T10/2 “10 pin connector, orange, in protective housing for connectors in plenum, left” pin 2. Reinstall connectors.
9) If voltage is not present at T8b/1, check for voltage at T6d/2 pin 2 of the 6pin connector on the fresh air blower switch. If voltage is present then the fresh air blower switch is bad or L45 “wire connection, in A/C harness” or the wires themselves between these two components are bad. Reinstall the connectors.
10) If voltage was not present on T6d/2 then check that voltage is present on T10j/1 “10 pin connector behind instrument panel, center.” You are down to just this connector and wiring between Fuse 25 and T6d/2. You did start out by verifying that Fuse 25 had voltage on both sides, right? Right?
This simple circuit test took me forever to write, and is best understood with the Bentley section 14 of the wiring diagrams, pages 97-152 to 97-156.
Original Posted 11/16/2005
By Jim Newkirk
adapted for TDI’s from September 2008 to May 1999 by Dan Goldston in October of 2008. Comments and new steps were added. No one has checked my work, here, so use this with caution. Don’t make expensive decisions without checking with another source, Dan.
“ The problem involved a 1999.5 Jetta TDI ALH manual A/C system with no compressor clutch operation. On this vehicle, the cooling fan and A/C compressor operation are controlled by the J293 fan control module, which is usually located in the driver's front corner of the engine compartment on the lower frame rail. The J293 module has both a 10-pin connector identified as the T10b connector in Volkswagen wiring diagrams and a four-pin connector identified as the T4a connector. ”
This summer has been a hot one, and I'm sure you have seen your share of air conditioning problems. Unfortunately, A/C systems have grown steadily more complex and difficult to diagnose.
The problem involved a 1999.5 Jetta ALH TDI manual A/C system with no compressor clutch operation. On this vehicle, the cooling fan and A/C compressor operation are controlled by the J293 fan control module, which is usually located in the left front corner of the engine compartment on the lower frame rail, sort of under the battery. The J293 module has both a 10-pin connector identified as the T10b connector in Volkswagen wiring diagrams and a four-pin connector identified as the T4a connector.
Before you really get started:
Check fuses 5, 25, and 16 on the fuse panel inside the cabin. Verify voltage on both sides.
Check fuses S164 and S180 on top of the battery. Verify voltage on both sides.
Bentley section 14 of the wiring diagrams, pages 97-152 to 97-156, is an excellent reference.
Never check continuity (ohms) on a circuit that has power to it. You’ll get bad readings and/or destroy your meter. Continuity for our purposes here, where we are checking switches and wires, means 0, zero, ohms.
Section A.
To diagnose this system, starting on the T10 connector:
1) Start and idle the vehicle. Select "A/C on" at maximum cooling and "blower on" at high speed (high speed just keeps the compressor loaded, signal development is the same for any speed).
1a) First check for 12 volts at pin 1 of N25, the AC clutch connector, if voltage is not present go to step 2.
1b) if 12 volts is present on Pin 1 of N25, then check for continuity to ground at pin 2 of the AC clutch connector.
1c) If these are both good, check for continuity through the clutch coil. It must be bad.
2) Check for 12 volts at the T10a connector pin No. 8 and 5 (T10b/8, T10b/5). This 12-volt signal comes from the A/C switch and requests both cooling fans on at low speed and compressor activation by the Fan Control Module. (Through fuse 25, the fresh air blower switch, the AC switch, F129 pressure switch , F38 ambient temperature switch, and F163 A/C high temperature cutout switch. This signal is also sent to the ECM, Engine Control Module.) If this voltage is not present, drop down to section B.
3) If you had voltage on T10b/8, and T10b/5, Check for 12 volts at pin T10b/9. This voltage is a switched ignition source and will have 12 volts when the ignition is in the "on" position.(Through fuse 5.)
4) Check for 12 volts at pin T10b/4. This is a constant battery source and should read 12 volts at all times from fuse S16.
5) Check for a good ground at pin T10b/6.
6) Check for 12 volts at all times at the four-pin connector, T4a pins T4a/4 and T4a/3 from fuses S164 and S180, respectively.
7) Check for an 11-volt reference voltage at pin T10/3. The reference voltage originates in the J293 fan control module and can be grounded by the control module (ECM) under certain circumstances (typically wide open throttle or vehicle overheat conditions) to turn the A/C compressor off.
7a)If zero volts are present, the PCM is commanding "compressor off" or the wiring harness is shorted to ground. Raise vehicle idle speed above 2500 rpm and observe compressor operation and voltage at pin T10b/3. If the voltage at pin T10b/3 returns to 11 volts with the idle speed above 2500 rpm and compressor operation resumes, then a throttle basic setting procedure is needed and must be performed with a factory-compatible, by-directional scan tool. Note: A loss of throttle basic settings will keep the compressor from activating. (I just left this section in from the 2000 and on version…I have no idea if this is the case for the early version of the vehicle or not, DanG144.)
8) If all previous tests have passed, check the T10b connector pin T10b/10 for 12 volts. This pin is the output signal to the compressor clutch coil. If all the other tests have passed and there is no voltage at pin T10b/10, this indicates a faulty fan control module. As you can see, turning on an A/C clutch is not a simple function on late model vehicles, and systems that you might not associate with an A/C problem can stop you and your customer from keeping cool. Be sure to check Direct-Hit's Hotline Archive section for more diagnostic procedures and tips.
Section B (from section A step 2)
If 12 volts is not present on T10b/8 and T10B/5 you need to find out why - and there can be many reasons.
1) Verify Fuse 25 is good, with voltage on both sides. Make sure.
2) Check the halfway point. Verify 12 volts are present on Pin 2 (blue and red wire) of the F129 connector (pressure switch located in A/C line near firewall and expansion valve. If not go to step 8, the problem is in the first half of the circuit.
3) So you had 12 volts on F129 pin 2, verify continuity from pins 1 to 2 on F129, and reinstall the connector. You should definitely have continuity if the A/C pressures are between 1.2 and 24 bar (17.4 and 348 psig). [The high pressure switch opens at 32 bar (464psig) and closes back at 24 bar (348 psig), so it is sometimes closed between these pressures and sometimes open] If continuity is good, reinstall the connector. If bad, check the pressures. If pressures are good and continuity is bad, you have a bad pressure switch.
4) If everything checks out so far, check 12 volts present at pin 2 of F38, the Ambient Temperature Switch. If not, your wiring must be bad from F129 to F38. If 12 volts is present at pin 2, check the continuity of F38. This switch should have 0 ohms if temperature is above 45 degrees F. (it opens at 30F, closes at 45 F). Reinstall the connector.
5) If everything checks out so far, check 12 volts at pin 1 of F163, the A/C thermal cutout switch. If 12 volts is not present, the wiring must be bad between F38 and F163. If 12 volts is present, check the continuity of F163. F163 should be closed (0 ohms, have continuity) unless the A/C temperature is greater than 234 F (opens at 246F, closes at 234 F.)
6) If everything is good so far, follow the green wire off of pin 2 of F163 until you find a junction - L10 – named “wire connection-2- in A/C wiring harness” the green wire is headed for pins T10b/8 and T10b/5. No further clues as to location. At this junction wires will connect from the three terminals mentioned (and PM Dang144 with the location, pictures would be good). Theoretically the car is still running with the A/C on and a fan speed selected, so be careful to not short these wires to ground. (More likely, after you locate this connection, turn the car and A/C back on to check the voltage. Have the car off if you disassemble and clean this connection.)
7) There is nothing left but wire to pins T10b/8 and T10b/5. IF the problem was in the second half of the circuit, you should have found it.
8) If the voltage in step B2 was bad at pin 2 of F129 the problem must be in the first half of the circuit. Check for 12 volts at pin T8b/1, the 8 pin connector on the A/C switch. If 12 volts is present then the problem must be in the wiring between these two components, which includes L9 “wire connection-1-in A/C wiring harness (pm DanG144 with location and pics) and T10/2 “10 pin connector, orange, in protective housing for connectors in plenum, left” pin 2. Reinstall connectors.
9) If voltage is not present at T8b/1, check for voltage at T6d/2 pin 2 of the 6pin connector on the fresh air blower switch. If voltage is present then the fresh air blower switch is bad or L45 “wire connection, in A/C harness” or the wires themselves between these two components are bad. Reinstall the connectors.
10) If voltage was not present on T6d/2 then check that voltage is present on T10j/1 “10 pin connector behind instrument panel, center.” You are down to just this connector and wiring between Fuse 25 and T6d/2. You did start out by verifying that Fuse 25 had voltage on both sides, right? Right?
This simple circuit test took me forever to write, and is best understood with the Bentley section 14 of the wiring diagrams, pages 97-152 to 97-156.
Diesel-Dan1
Veteran Member
Great post here.....got lots of info to test with....here is what my car is doing:
How it started: The AC would just stop working for a bit and then come back on. Ran fine for months.
Now what its doing: Last weekend i was sitting in a lot on the computer...and the compressor just stop running....got warm air out of the vents. Just in time for a big thunderstorm that fogged the windows up as well....yeah...was a blast. I drove back from Iowa to MO with No AC in 80-90* Temps.....was fun.....but not too bad...
BUT i have noted that if i sit in the car at night and the engine temps get high enough, the high fans will come on and then...boom...the AC compressor starts and i got AC again until i shut the car down.
I am going to go through the list posted above...but im almost certian its my FCM as the fans do not come on when the AC is turned on at idle. BUT the AC light is on...and VAG-COM picks up the signal as well when i turn it on and off.....so my assumption is that the dash switch is doing its thing.
SO....more or less thanks for all the info...ill keep posted on what i find after testing out stuff.....
How it started: The AC would just stop working for a bit and then come back on. Ran fine for months.
Now what its doing: Last weekend i was sitting in a lot on the computer...and the compressor just stop running....got warm air out of the vents. Just in time for a big thunderstorm that fogged the windows up as well....yeah...was a blast. I drove back from Iowa to MO with No AC in 80-90* Temps.....was fun.....but not too bad...
BUT i have noted that if i sit in the car at night and the engine temps get high enough, the high fans will come on and then...boom...the AC compressor starts and i got AC again until i shut the car down.
I am going to go through the list posted above...but im almost certian its my FCM as the fans do not come on when the AC is turned on at idle. BUT the AC light is on...and VAG-COM picks up the signal as well when i turn it on and off.....so my assumption is that the dash switch is doing its thing.
SO....more or less thanks for all the info...ill keep posted on what i find after testing out stuff.....
DanG144
Top Post Dawg
I would make sure that your low speed fans work, first.
http://forums.tdiclub.com/showthread.php?t=242699 may help you troubleshoot. Try the links at the bottom of post #1.
http://forums.tdiclub.com/showthread.php?t=242699 may help you troubleshoot. Try the links at the bottom of post #1.
Diesel-Dan1
Veteran Member
Thanks...i got your write up printed...i just need to find time to do it...im currently moving from MO to TX in the next two days...hence why i wanted to get the AC fixed.....haha...DanG144 said:
NOW if the low speed dont work....that could be the Temp switch, Fans or the FCM.....right? I skimed though it pretty quick...but that is the more or less i got out of it...
Ill ck the link out...thanks!
Also did that Fan output test with VagCom.....didnt run the fans at all.....
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DanG144
Top Post Dawg
That means that the ECU could not get the fans to run via the FCM.
I would try the thermoswitch tests first, that bypasses the FCM. If they do not work on this test, then put power to the fans directly.
And do not be surprised if it turns out you have multiple issues; fix one and still have to troubleshoot further.
Good luck.
PM if you need to.
I would try the thermoswitch tests first, that bypasses the FCM. If they do not work on this test, then put power to the fans directly.
And do not be surprised if it turns out you have multiple issues; fix one and still have to troubleshoot further.
Good luck.
PM if you need to.
Diesel-Dan1
Veteran Member
Thanks sir....ill make sure i find my trusty test light.....DanG144 said:
Ill prob talk to you early next week when i will be able to look at the car
Diesel-Dan1
Veteran Member
haha...wouldnt you know it when i packed up and left for TX the AC has worked perfect since last friday....only one small hicup for about a half hour on the trip home...but otherwise fine....hard to troubleshoot a working system...going to have to wait until it messes up again.....o well...ill take it while i have it i guess!
je
Veteran Member
Earlier this week my A/C quit 1500km from getting home during a trip. When I went to check voltage and resitance at the clutch.... the plug dangled loose in my hand. It had popped off on its own! What a relief!
Maybe have a look at that?
Maybe have a look at that?
laundryeater
Veteran Member
Here's one to dig this thread out of the grave:
I was getting no AC when I hit the AC button, the light turns on and the fans would turn on low speed. I did the troubleshooting guide except the duty cycle test and all of those were ok except I was getting 9 volts for the compressor. I changed out the fan control module with a new one and now my fans run at high speed no matter whether the AC button is pressed or not, however, the fans turn off when I unplug the pressure sensor, even when the AC button isn't pressed. I now get 0 volts at the compressor and all the other voltages measure out OK. Anybody have any thoughts?
I was getting no AC when I hit the AC button, the light turns on and the fans would turn on low speed. I did the troubleshooting guide except the duty cycle test and all of those were ok except I was getting 9 volts for the compressor. I changed out the fan control module with a new one and now my fans run at high speed no matter whether the AC button is pressed or not, however, the fans turn off when I unplug the pressure sensor, even when the AC button isn't pressed. I now get 0 volts at the compressor and all the other voltages measure out OK. Anybody have any thoughts?
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DanG144
Top Post Dawg
It sounds as if you need a new High pressure sensor.
I will be working around the shop this afternoon, checking out someone's AC.
I have a spare HP sensor and spare FCM, we could troubleshoot yours as well.
Dan
I will be working around the shop this afternoon, checking out someone's AC.
I have a spare HP sensor and spare FCM, we could troubleshoot yours as well.
Dan
laundryeater
Veteran Member
Oh cool! Does the pressure sensor replacement require the freon to be taken out?
DanG144
Top Post Dawg
Nope.
laundryeater
Veteran Member
I'd definitely head down to see you today if you weren't 145 miles away and I had to work tonight. What is a way I could confirm that it's the pressure switch that's giving me trouble?
DanG144
Top Post Dawg
The only sure way is to measure the duty cycle output and verify that it is correct for the ambient temperature, on an idle system. Or compare the duty cycle to a high pressure side gauge.
Or if you see oil coming out the electrical connector on the FCM?
If your FCM is good, then the test you did is pretty definitive- fans run continuously on high and clutch disengages (even with engine off or when just started for the first time of the day) unless the sensor is unplugged. I just worry that your FCM may be bad, even though you have replaced it. I seem to remember similar posts from folks that just put on a new FCM, and the FCM was bad.
Or if you see oil coming out the electrical connector on the FCM?
If your FCM is good, then the test you did is pretty definitive- fans run continuously on high and clutch disengages (even with engine off or when just started for the first time of the day) unless the sensor is unplugged. I just worry that your FCM may be bad, even though you have replaced it. I seem to remember similar posts from folks that just put on a new FCM, and the FCM was bad.
laundryeater
Veteran Member
The new FCM is a Meistersatz from idparts. It sounds like it's doing the right thing if the pressure sensor is malfunctioning according to your description. This is what I probably need then, right?
http://idparts.com/catalog/product_info.php?products_id=1918
http://idparts.com/catalog/product_info.php?products_id=1918
DanG144
Top Post Dawg
Yes, that is the three wire high pressure sensor. Verify that you have a 3 wire connector, and not the older 4 wire - which is a true switch, not sensor.
laundryeater
Veteran Member
A new pressure sensor got the AC going again in my car. At first I had about a 9.5V reading at the compressor clutch coil (regardless of the AC switched on or not in the cabin) and replaced the fan control module which dropped the voltage reading to 0. After replacing my FCM the radiator fans ran on high speed at all times the key was switched on. Unplugging and plugging the coolant pressure switch turned the fans off and on. Replacing the pressure switch got the system working again. So it seems like I had both the FCM and the pressure switch in need of replacement. I hope this helps someone else with their AC woes.
DanG144
Top Post Dawg
Good to know, glad it worked out.
Dan
Dan
laundryeater
Veteran Member
Ah! Now it's not working again today. Guess it's back to square 1. The AC button gives me nothing- it lights up but the fans don't kick on. I wonder if I lost some charge when I changed out the pressure switch. Should have been completely insignificant though.
DanG144
Top Post Dawg
If the AC button is not lighting, it is usually the fan resistor bank or the switch itself.
Check the fuse as well (34?, 5?, 16?) http://forums.tdiclub.com/showthread.php?t=242699 pdf in post #1 has the details.
Dan
Check the fuse as well (34?, 5?, 16?) http://forums.tdiclub.com/showthread.php?t=242699 pdf in post #1 has the details.
Dan
laundryeater
Veteran Member
I'm going to get a meter that can measure duty cycle because the temperature is the only thing that would have changed between the 12 hours that the AC was working and when it was not... unless something took a little time to get fried.
laundryeater
Veteran Member
Low duty cycle... around 20%. So I need a charge, correct?