Check your radiator/condenser fan operation NOW

TheKid7 said:

I went to AutoZone and had the Alternator, Starter and Battery tested. The Starter and Battery were good. The Alternator output was low. AutoZone said that my car has a 120 amp Alternator and that a Good Alternator should put out 60 amps during the test. The Alternator was putting out 44 amps. AutoZone said that the minimum is 40 amps.

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I confirmed that I have a 90 amp Alternator (2003 VW Jetta TDI (Automatic Transmission)).

Also, I went to a local shop that rebuilds Alternators and Starters. They performed a much more thorough testing of my Alternator using a very Professional looking Snap-On Tester. They reported that the Alternator output is fine and therefore there is no need to change the Alternator at this time.

TheKid7 said:

I confirmed that I have a 90 amp Alternator (2003 VW Jetta TDI (Automatic Transmission)).

Also, I went to a local shop that rebuilds Alternators and Starters. They performed a much more thorough testing of my Alternator using a very Professional looking Snap-On Tester. They reported that the Alternator output is fine and therefore there is no need to change the Alternator at this time.

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I'll be taking my car to runonbeer later in the week, so Rob will have a chance to check out the pulsation noise in mine. I bet that his idea that it might be the alternator pulley will turn out to be the case.

My car does this more when the engine is warm. On a hot day, after a highway trip, if I come up to a red light, I really notice it.

halocline said:

I'll be taking my car to runonbeer later in the week, so Rob will have a chance to check out the pulsation noise in mine. I bet that his idea that it might be the alternator pulley will turn out to be the case.

My car does this more when the engine is warm. On a hot day, after a highway trip, if I come up to a red light, I really notice it.

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Could the problem be the belt tensioner? I only have the problem when the AC is on. Would it be recommended to leave the AC off until the problem is resolved? I don't want to snap the serpentine belt.

TheKid7 said:

Could the problem be the belt tensioner? I only have the problem when the AC is on. Would it be recommended to leave the AC off until the problem is resolved? I don't want to snap the serpentine belt.

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Sure, as far as I know it could be lots of things. The reason you only notice it with the AC on is because that's when the fans come on.

TheKid7 said:

Could the problem be the belt tensioner? I only have the problem when the AC is on. Would it be recommended to leave the AC off until the problem is resolved? I don't want to snap the serpentine belt.

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Here's what we tried:

1. Alternator pulley, made no difference

2. Unplugged each fan (separately). The pulsing stopped with the large fan off, and changed, almost disappeared, when the small fan was off.

3. Tried a new large fan. No difference.

The next thing might be to try a new small fan, but I'm doubtful that would make a difference.

It's a really deep pulsing, you feel it more than here it. It does not seem to affect the idle speed. I'm looking for ideas at this point.

halocline said:

.......snip I'm looking for ideas at this point.

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Drive more, worry less!

halocline said:

Here's what we tried:

1. Alternator pulley, made no difference

2. Unplugged each fan (separately). The pulsing stopped with the large fan off, and changed, almost disappeared, when the small fan was off.

3. Tried a new large fan. No difference.

The next thing might be to try a new small fan, but I'm doubtful that would make a difference.

It's a really deep pulsing, you feel it more than here it. It does not seem to affect the idle speed. I'm looking for ideas at this point.

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I plan to not further investigate my "similar problem" at this time. I will just live with it for now. The problem seems to bother me a lot less since I have decided to just live with it for now.

Every time the engine warms up, the problem seems to go away.

Thank you for your input.

steelmb said:

Drive more, worry less!

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I definitely like the worry less part! Driving more, I don't know, I do plenty of that!

Actually, back to the OP -

I had to change my Fan Control Module, too, along with the driver's-side fan, as the high-speed was not working.

Spike Strip said:

Actually, back to the OP -

I had to change my Fan Control Module, too, along with the driver's-side fan, as the high-speed was not working.

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It is not uncommon at all for an A4 to have two fans inoperative on slow speed, and still another problem - pressure transducer, ambient temperature sensor, compressor or clutch or FCM.

I am guessing you tested high speed fan operation to find it bad? Unless both slow speed fans are bad, high speed is rarely called for.

Good job.

Yes - tested following your procedure - (which I should have done first )
and found high-speed inoperable on both fans once the new fan was installed - again, using your procedure to rule out components, a faulty FCM was indicated.

Man that FCM is a giant PITA to remove! (learning curve... )

And while I had it up , I changed oil to M1 TDT and changed the 09A tranny fluid following other threads on this site.

She runs great!

Thanks again for the great thread - wouldda been much harder to do this without it.

I owe ya a couple a beers when I go to visit my Nephew (currently a guest of S. Carolina Dept of Corrections )

cheers,

Alf

Be sure to let me know when you come, and we will visit.

Someone recently asked me for the resistance readings of a good high pressure sensor. I cannot find where or who.

But here goes:
Pin near square end as common.
to middle pin 511k ohms.
to round end pin 280k ohms.

Any pin to engine ground, greater than 2M ohms.

I hope whoever needed it finds this. Sorry to take so long to answer the question. I have been working some long night shifts, and have been lucky to get anything extra done.

Ok, I'm completely stumped; the fan doesn't blow even slightly anymore unless you put it to '1' on the fan. The re-circulator for the air is working. The horn and lights are working, so it isn't the relay. The A/C clutch is on, but it doesn't engage. The system seems to be fully charged; finally, I came across this page and found that the fan on the driver's side of the car isn't working. The dealer says that the compressor is shot and the module might have to be replaced.

Any thoughts? I'm completely lost here.

Wait on the dealer. Unless they did some troubleshooting you are not mentioning it is very early to be talking about that kind of expensive repairs.

What year and model is the car? Does it have a plain manual AC system, or a Climatronic system?

Talk more about the cabin fan. Does it blow only on high speed? or only on low speed? Explain in detail when it will blow and when it will not.

Try putting the cabin fan on high speed (even if it will not blow there), does the AC compressor now engage? If you cycle between high speed and low speed cabin fan do you get a brief spurt of cold air?

The driver's side fan will have to be replaced, almost certainly. Inspect the visible wiring to the fan. If it is intact, then you will have to have a fan.

It's a 2003 Jetta TDI 162k. Plain A/C, and the clutch doesn't engage at all.When I cycle the fans, I get no cold air at all. The wiring to the fan is visible, but I can't see any specific raw-wire exposure. What do you think?

Tell me more of your cabin fan, as asked in the post above. Does your cabin fan work reliably on all speeds? If not what speeds do what?

Also get out and look at your AC clutch while someone goes through all the cabin fan speed selections. See if it ever engages.

The driver's side fan will have to be repaired or replaced. (Unless you already have the tools to take it apart, replacement is the best option.)

The fan does not blow softly as it should when the switch is set at 'off' It blows properly at all other speeds, 1, 2, 3 and 4. I had noticed in the past that it would blow very softly at 'zero', and when I started to put it at 1 to get air, I thought nothing of it. I have checked to see if the clutch engages at any speed, it never moves.

To repair the cabin fan, I will need at least a dremmel, which I have, and the heads to undo the bolts. If the brushes are damaged beyond repair, I'll have to order a new fan, unless you know where I can get some brushes.

But I'm confused; how could it be that this fan alone failing could be the cause of all of my troubles? Surely something else is causing the A/C clutch not to engage, isn't it?

I am calling the cabin fan the one inside the cabin, that blows in your face.

The driver's side fan needs to be fixed, but it will not solve all (or even most of) your problems.

Thank you for the information about your cabin fan. It does not blow at all when off. It allows outside air to blow through the cabin, unless you have the switch set on recirc, but the fan does not turn.

I was confused by your earlier post, and thought that you were having issues with your cabin fan not working on some speed, which can impact your circuitry and prevent the AC from energizing.

Now, when you turn the AC to on, key on, and the cabin fan speed set to any number, does one of your radiator fans turn on? I understand that one is bad and will not turn on.

efb,
What makes you say "the system seems to be fully charged?"

I am calling the cabin fan the one inside the cabin, that blows in your face.

The radiator fan towards the passenger side of the car is the only fan that I see running. It starts immediately when I start the engine, and when I turn the A/C on, I can see no visible change in the working fan's speed, and of course, the second fan towards the driver's side doesn't turn on at all.

I've already checked the charge on the system; I thought that after 162k maybe there was a leak and I needed to recharge the system. The system didn't need a charge at all; I didn't really think there was a leak to begin with, I was just hoping it was something simple.

Thank you, by the way, for helping me with this, Dan. I really can't afford to pay the dealership to do it, so I really appreciate you helping me out.

I checked my fans and they didn't run.Bought from Walmart 1 can R-134a with a gauge and checked the pression-too low.Put some in and the fans started,but still no cold air coming.I did empty the can(690ml) and felt cold air coming out.But it blows cold for about 1 minute and stops.Everything works(fans-on,compressor-on),but no cold.Then installed the gauge back on the pipe and it showed between 70 and 100 psi.Started the A/C and the pression dropped upto 50 psi and was blowing cold.In 1 minute it stops blowing cold and pression goes back to 80-90 psi,but compressor and fans are runing.If I turn it off and wait about 5 minutes,then can repeat it again.
Any ideas?Thanks

efb91 said:

I am calling the cabin fan the one inside the cabin, that blows in your face.

The radiator fan towards the passenger side of the car is the only fan that I see running. It starts immediately when I start the engine, and when I turn the A/C on, I can see no visible change in the working fan's speed, and of course, the second fan towards the driver's side doesn't turn on at all.

I've already checked the charge on the system; I thought that after 162k maybe there was a leak and I needed to recharge the system. The system didn't need a charge at all; I didn't really think there was a leak to begin with, I was just hoping it was something simple.

Thank you, by the way, for helping me with this, Dan. I really can't afford to pay the dealership to do it, so I really appreciate you helping me out.

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efb,
You are welcome.
So something is causing your fans to be requested to run continuously, but is not allowing your AC clutch to engage.
Can you tell if the fan is in fast speed or slow? It can be hard to tell if you are not familiar with them - and most people are not.
The slow speed fans can be requested by:
1) AC on with normal pressure.(would normally also request clutch on).
2) radiator thermoswitch on (would not impact AC clutch operation).
3) ECU high temperature (MAY turn off the clutch.)

If AC pressure sensed is high, it will run your fans continuously on high any time the key is on.

Go back to post #1, read through the AC troubleshooting guides, find the photos of the high pressure sensor and unplug it. See if this turns your fans off. If it does, and your high side pressure is less than the value specified in the table (which it will be unless you have grossly overfilled the system, since the clutch is not engaging), then you have found a second problem (besides the broken fan.)

I recently found out our AC fan was totally kaput during a major service. We had been noticing reduced cooling at stand-still. When removed the fan was bent off center and did not rotate at all. wonder if a stick got in there or something.

What shoud the pressure be at the low and high pressure valves and how to take the test.I did empty one can in.Now a/c blows cold for 1 min. and stops blowing cold air.The fans are on,compressor is runing engaged,but no cold air.If I turn the a/c off and wait 5 min and turn it back on does same.If you guys have some idea let me know.Thanks in advance.

At 1500 rpm, blower speed to fast, max cooling. You should have about 200 psi on the high pressure side, and 17 psig on the low pressure side.

It can be dangerous to just add refrigerant to a system, without knowing how much is already in the system. An overcharge can take the compressor discharge side completely full of liquid (no gas space left) and cause pressures to skyrocket, popping safety valves, challenging control systems, and potentially breaking hoses, tubes and compressors.

High Kinetic Energy rotational disassembly of the compressor can be hazardous to your person. That is pentagon speak for blowing it up.

A year or so ago I had done a "repair" of the resistor in the fan and it eventually failed (probably my soldering skills if anything else). Advance auto parts had a coupon thing going for 15% off, so I got their Doorman replacement unit (Part No: 620-799), ended up being $110 and it arrived the next day. It comes with the housing and everything. I did take the fans off the new housing and drop them in the car, everything plugged right in - I didnt feel the need to fight the housing out of the car. So for whatever its worth, the Advance Auto Parts replacement unit is of decent quality and blows like a champ, also the blades were properly balanced. While I was replacing the fans it occurred to me that an option to consider if the resistor is fried is to just wire it up so that when the A/C system calls for low fan it just goes on high instead bypassing the resistor - after all, high is better than off....

Thank you Dan,
How should I relieve the pressure,but not in the atmosphere.Can I take some refrigerante back in a can or so.I have too high pressure on the low pressure valve-about 40-55psi on idles and then goes upto 80-90 and stops blowing cold.I don't have a gauge for the high pressure valve port,but I saw a kit in a Schucks store for 60-70 bucks and I am considering to buy one.

Superdiesel,
I have tried to keep this thread mostly on the electrical end of the system. This is because even knowledgeable auto HVAC techs can get fouled up on the electrical side.
The low pressure side being high in pressure is not a symptom of too much refrigerant.
You can make no real decisions on this car without a complete set of gauges. It is DANGEROUS to just add refrigerant with those cheap kits that have only the low pressure gauge.
If you do not keep the right mix of oil and refrigerant, your system will die young.
You either need to take it to an HVAC tech, or do a lot of studying, then get the proper tools.

Thank you.I'm waiting for a Vag-com cable and will see what it will show.