AC stopped blowing cold

NurseGuy1987

Well-known member
Joined
Nov 18, 2018
Location
Sylvania, GA`
TDI
2003 Beetle TDI
Hi guys. Here I am again with what is probably a simple issue. My AC has bwwn cooling "okay" since I purchased my car. This evening, I turned it on and it didn't cool. I hooked up a bottle of AC pro and tried "charging it" until it was in the green zone (on the ac pro bottle). Once it got into the green zone it still wouldn't cool. I was not able to check fans or the compressor clutch as I simply don't know enough about it. The fan inside blows strong, the AC light comes on when I push the button, as well as the recirculate button. It was working fine yesterday. What gives?!? Should I be concerned about overheating, as I was told that the thermostat has something to do with heating/cooling? What are some things to look for (and how)? Thanks in advance. Also, the doors are all working properly between floor, defrost, vents, etc. Also note, that it has been blowing out pieces of black/gray foam type material since I purchased it.

2003 MK4 TDI Beetle
100,290 miles.
 
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Nero Morg

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Oct 19, 2017
Location
OR
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2014 A6 TDI, 2001 Jetta TDI, 2014 Passat TDI
Either your system is overcharged, underchargrd, or your fans aren't working. An underchargrd or only one fan working will make your ac only kind of work. Turn your ac on with the engine running and take a peek just in front of the engine. You should see both fans running. If they aren't, there's one issue.
 

KLXD

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Joined
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Location
Lompoc, CA
TDI
'98, '2 Jettas
The above is true but it's not as simple as that.

These have variable displacement compressors. They can stop compressing on a fully charged system even though the shaft is rotating.

All that gauge told you is that there is some pressure in the system, probably enough for the pressure switch to allow the compressor to run.

So, if the fans are running check the compressor to see if the shaft is turning. The plate inside the the AC pulley is the clutch. When the pump is on it should rotate with the pulley. Check that.

Do some searching but I think that on a MK4 when the foam starts deteriorating the heat mixes with the cold so check if the AC is cold before the engine heats up. The fact that it was cooling before makes me think the foam isn't your problem. I don't see it going from OK to no cooling overnight.

If the fans are working and the pump shaft is turning you really need to put a set of real gauges on it but even that won't tell you if you have the proper charge in it. Need to evacuate it and recharge.
 
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NurseGuy1987

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Joined
Nov 18, 2018
Location
Sylvania, GA`
TDI
2003 Beetle TDI
Thanks guys/gals(?). I really appreciate your input. I hope it isn't the airbox (heater box) door thingy. That looks like a royal pain in the A$$ to take apart.

Variable Displacement compressors: I'm hoping this is the culprit. I honestly do not hear the compressor engaging like I normally do.

Fans: Haven't checked yet, but this will be done in the morning once I clock out from work.

Foam: I wonder if all of the foam has now dislodged, as it has been blowing chunks for months! Some pieces large, others minute. However, it was blowing just fine yesterday. It blew cold before and after engine warm up. Now, it blows hot even when the engine is cold. Turn the knob to heat, and it gets hot as it normally should.

If all else fails, I suppose I will be dipping into savings, as the South Georgia summer is not far away and triple digits temps are not uncommon for extended periods of time.
 

KLXD

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Joined
Aug 22, 2009
Location
Lompoc, CA
TDI
'98, '2 Jettas
Not to mention high humidity too?

If the compressor clutch isn't engaging and no fuses are bad I think that can indicate a bad fan control module.

I'm kind of spitballing here. Do some searching in the TDI101 and MKIII Forums. I think there's a troublshooting guide for AC.

It's at the top of this Forum: "Check your radiator..."
 
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jokila

Vendor
Joined
Dec 3, 2004
Location
Houston, Texas
TDI
2003 Jetta GLS, Manual
Often what goes bad is the RCV - refrigerant control valve. On the Mk4s it's internal, but way cheaper to replace that than the whole compressor.
 

NurseGuy1987

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Joined
Nov 18, 2018
Location
Sylvania, GA`
TDI
2003 Beetle TDI
think it would be best to take it to a trusted mechanic, one who I know won't nickle and dime me to death. I really don't have the knowledge neccessary nor the time (thanks to working crazy hours) to do it myself. I just want it fixed. :-( Adulting is SOOOOO not what we thought it was as children! I want to go back to the 1990's and enjoy life again.
 

NurseGuy1987

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Joined
Nov 18, 2018
Location
Sylvania, GA`
TDI
2003 Beetle TDI
Also, if all of the foam is missing from the blend doors, wouldn't that cause it to not cool? Obviously I need to check the compressor and fans before breaking down the dash, but, if everything up front checks out, then I can only deduce that it would be the blend doors.
 

KLXD

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Location
Lompoc, CA
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'98, '2 Jettas
Did you look at that thread or just read the title?

Yeah, the RCV is what controls the displacement of the pump if I understand how it works correctly.
 

NurseGuy1987

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Nov 18, 2018
Location
Sylvania, GA`
TDI
2003 Beetle TDI
which thread are you speaking of? I have read about 15 between this site and another forum. I'm just trying to get clarification on the door, whether or not it would cause the AC to blow hot, and if it could be something as simple as replacing the blend door. Obviously, it needs to be troubleshooted.
 

WildChild80

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May 30, 2016
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Nashville, AR
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2001 Jetta TDI 2000 Jetta TDI 2000 New Beetle TDI ALL 5 speeds
When I lost the foam off my doors, it would still blow cool not super cold but the heat wasn't there and one winter I thought I was either going to freeze to death or crash from the condensation and obscured vision because it was warmer when the fan was off, long road trip that sucked.



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WildChild80

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May 30, 2016
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Nashville, AR
TDI
2001 Jetta TDI 2000 Jetta TDI 2000 New Beetle TDI ALL 5 speeds
crazy. i have GOOD heat and crappy air! FML
Part of owning these cars is you kinda need to be at least a tinkerer if not some degree of mechanic. If you're in medicine, it's much the same...cause and effect, but you have to learn how cars talk and what and when they're saying it. I've enjoyed driving a car that I love to drive, get stupid fuel mileage, torque...oh the torque and not having a car note for a good long while.

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NurseGuy1987

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Nov 18, 2018
Location
Sylvania, GA`
TDI
2003 Beetle TDI
I love my little bug. LOVE the gas mileage, and LOVE LOVE LOVE not having a car payment. My last car note was nearly $700/month and that was not including the $350/month insurance premium. My mom has driven a few VW's, the most recent was a 1985 Cabriolet convertible. It had nearly 500,000 miles on it and she ran a stop sign, got t-boned by a town car, and then was still able to drive it home. Granted, it was wounded, but it still got her home safely.
 

KLXD

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Aug 22, 2009
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Lompoc, CA
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'98, '2 Jettas
It's currently the very first thread in this, the VW MKIV-A4 TDIs (VE and PD) Forum.

The Title begins with "Check your radiator..."
 

jokila

Vendor
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Dec 3, 2004
Location
Houston, Texas
TDI
2003 Jetta GLS, Manual
Did you look at that thread or just read the title?

Yeah, the RCV is what controls the displacement of the pump if I understand how it works correctly.
If you are referring to my post, i most certainly understand. If AC stops blowing cold or just cool, then as long as the other parts are working fine (fans turn, freon level good, etc), then the RCV can be suspect.

It gets contaminated and doesn't work, or fails all together.
 

NurseGuy1987

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Joined
Nov 18, 2018
Location
Sylvania, GA`
TDI
2003 Beetle TDI
Okay, so this morning it was around 35* (F) and I turned the key (not cranking) and pushed the AC button. I turned the blower to high and the light came on, and the vents blew air. I went to the front to inspect the fans, neither of which were operational. I'm not sure when the fans are supposed to come on and when they aren't. IF there isn't enough charge in the AC system, is the fan still supposed to kick on? The large fan wasn't spinning either, but again, the engine was cold. When are the fans supposed to come on? Knock on wood, I have had no overheating issues.
 

KLXD

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Joined
Aug 22, 2009
Location
Lompoc, CA
TDI
'98, '2 Jettas
If you are referring to my post, i most certainly understand. If AC stops blowing cold or just cool, then as long as the other parts are working fine (fans turn, freon level good, etc), then the RCV can be suspect.

It gets contaminated and doesn't work, or fails all together.

Sorry for the misunderstanding, I was agreeing with you.

The first sentence was directed at the OP. The thread I pointed him to doesn't mention AC in the title but it does have AC troubleshooting if he had looked at it.
 

Genesis

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Feb 26, 2003
Location
Sevier County TN
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'03 Jetta Wagon
At 35F you may be below the required temperature. Try when mid 40s or better.

With the key on (but not running), fan anywhere other than OFF and button in the light should come on and BOTH fans behind the radiator should run on low.

If they don't then most-likely:

1. There's NO charge in the AC system, or the transducer is saying there is no pressure. That is NOT a switch by the way, it's a PWM sender, so you can't just short it. The system will not attempt to come on if it thinks there's no charge (under ~30psi or thereabouts) in it.

2. It's too cold or the temperature sensor is lying (the car thinks its too cold); it won't engage below about 40F.

3. The fans themselves are dead, the fan controller is dead or there's no power to it (wiring, fuses, etc.) The large (driver side) fan seems to fail *much* more often than the small one.
 

NurseGuy1987

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Nov 18, 2018
Location
Sylvania, GA`
TDI
2003 Beetle TDI
turned the key on (not running). Fan speed on high. ac light turns on. Fans do not. I do recall that when i connected my ac pro bottle the gauge red "no charge". I filled it until it read "30" on the gauge on the bottle, but I highly doubt those gauges are very accurate. Would it also not turn the fans on if it were OVERCHARGED?
 

Genesis

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Sevier County TN
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'03 Jetta Wagon
There is only one sensor and it's on the high side. If your low-side gauge on the bottle read 30psi, even if off by a fair bit, the fans should run.

However, if there was no charge then it went somewhere and if the unit stopped working suddenly but was working fine previously then odds are it "went" more-or-less all at once. :)
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
DanG144'sa thread (sticky) covers the AC pretty complete and was written with your car as a basis.
 

CoolAirVw

Vendor
Joined
Nov 9, 2005
Location
Kansas City Missouri
TDI
Jetta
You sent me a personal message but I thought it would be better to reply here.

There is a ton of stuff it could be. Start with a look to see if AC clutch is on. Check 3 small fuses in the battery fuse box. And the fuses that relate to the AC in the "dash" fuse box.

The info other folks have referrred you to is very helpful, but here is some common stuff I see.

Blend door bushing (pin) can break and make the blend door uncontrollable. Here's a video on that. This can be checked and changed fairly easily. Video shows bushing while doing heater core and blend doors but if its broken you can see the falling out of the heater box and it can be changed without major work. Can be purchased on my website.

https://www.youtube.com/watch?v=2Yz2p1apm_w

Of course the blend doors can be shot causing hot air to mix with cold air making AC very poor.

AC clutch can fail, It can be changed without replacing the compressor. I had a video on that but about half of the video was corrupted so I never posted it. I'm sure I'll do another video on this later this summer as AC season starts.

Refrigerant control valve can fail, Here is a video on that.

https://www.youtube.com/watch?v=qtrXyrHfScM&t=7s


AC pro being in the green doesn't mean its charged right. AC machine that weighs the quantity put in is the only way to do it right.
 

JB05

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Oct 20, 2005
Location
Il.USA
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Golf,2005,anthracite blue
As mentioned above, the AC does not turn on below 40F. There is a sensor that monitors the ambient temperature. On my Golf it is under the windshield cowl on the extreme left side.
 

NurseGuy1987

Well-known member
Joined
Nov 18, 2018
Location
Sylvania, GA`
TDI
2003 Beetle TDI
thanks everyone. I am taking it to a local mechanic on my next day off (monday). Stuck at the hospital until then pulling a 36 hour rotation. Hopefully it will be something simple. If not, I may just have to sweat a bit until I can save up some extra cash. South Georgia summer is right around the corner and triple digit temps do not agree with me!
 
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