No A/C while moving

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Joined
Apr 10, 2018
Location
Houston
TDI
2003 VW Golf
Hey all! I've had my 2003 Golf roughly 9 years and the A/C has never worked properly. I have ice cold air at startup but once everything warms up and I'm moving the air gets warm. Once I come to a stop again it will cool off temporarily but won't be as cold. I checked the air blend doors while I had the dash apart, assuming hot Texas air was getting pushed through, but no dice they look like new. I have verified that both cooling fans work, I have good pressure on the low side, and the compressor clutch is engaging. It feels like the clutch is engaged even when I'm getting warm air but it's hard to tell since I'm moving. Any ideas for things to check or possible causes will be appreciated!
 

Nero Morg

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Oct 19, 2017
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OR
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2014 A6 TDI, 2001 Jetta TDI, 2014 Passat TDI
These compressors are variable displacement pumps, they're difficult to diagnose on pressure alone. It could be under or overcharged. Have you ever had it evacuated and filled to spec? Might not be a bad idea to replace the filter dryer while it's out.
 

Typrus

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Jun 25, 2004
Location
BCS, TX, USA
TDI
2002 Black Jetta Sedan GLS/TDI 5mt
The only correct way to fill an R-134a system is by weight. Pressures can remain good across a decent weight range, but system performance can still suffer.
It may not hurt to have it vac and filled, new drier at the same time.
Check your HVAC drain as well, make sure it drains freely.
I'd start there, but you may also have TXV issues, compressor issues, evaporator partial icing... could be a number of things.
 

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Apr 10, 2018
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Houston
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2003 VW Golf
Thanks for the input fellas. I probably should have mentioned that the ac has never been serviced, to my knowledge. If I get the r134a flushed and refilled with a new drier, probably TXV as well, how likely is it to solve the issue? If it's 50/50 I would probably just replace the compressor and condenser as well to avoid having to flush and refill more than once. Is there a good way to rule these two out? They are the most expensive/ labor intensive to replace from what I can tell. Thanks again!
 

Typrus

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Jun 25, 2004
Location
BCS, TX, USA
TDI
2002 Black Jetta Sedan GLS/TDI 5mt
Without putting hands, gauges, and recovery scale on it, it is very hard to say.
I'd hate for you to go through all of that and find out you have an evaporator issue- that's serious labor.
Here's a thought, you could pull your blower motor and inspect for debris and gunk in the housing. Restricted flow contributes to evaporator icing issues, especially with the lovely humidity we have. In addition, make sure your cab filter is fresh.
Those are pretty easy DIY checks, I'd recommend starting there.
The other thing to check is to see how cold the lines are getting at idle, revved up, then real quick after a brief jaunt where it starts warming up- compare results.
I also forgot to ask... when it starts to warm up, does the airflow out of the vents seem to reduce or stay about the same?
 

IndigoBlueWagon

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Aug 16, 2004
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South of Boston
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'97 Passat, '99.5 Golf, '02 Jetta Wagon, '15 GSW
I would have a tech look at high and low pressure levels. It's possible your expansion valve is sticky or dead. And if the pressure differential gets too great the compressor will de-clutch to preserve the system. If it is bad you can put lubricant in the system that will (sometimes) free it up.
 

Mongler98

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Mar 23, 2011
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98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
85% of HVAC issues is electric related. Gauges come out last.
Also filter dryers are mandatory to replace and must be back purged with nitrogen to install. Also by weight is not the only proper way to add refrigerant. There is a supper cool supper heat method and basically 134a is very forgiving that at a specific ambient temp and within a specific high and low pressure is fine. But you need a set of gauges and not the pos on the can.
Dont go down this rabbit hole unless committed to doing it right.
 

Typrus

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Jun 25, 2004
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BCS, TX, USA
TDI
2002 Black Jetta Sedan GLS/TDI 5mt
The correct way is by weight. Period.
Other ways can be done, if you account for temperature, humidity, system condition, etc.

Of the hundreds of R-134a systems I have troubleshot and repaired over the years, I have enough digits to count the ones that were electrical faults. Does it happen? Yes, yes it does.
 

Genesis

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Joined
Feb 26, 2003
Location
Sevier County TN
TDI
'03 Jetta Wagon
MKIv systems with the RCV in the compressor is essentially impossible to *accurately* check by pressures. Yes, you can do the calculations BUT they assume exactly ONE expansion orifice -- at the TXV. There are two in the MKIv system and as such you'll be wrong. Maybe close enough for government work, but not correct.
 

AndyBees

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May 27, 2003
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Southeast Kentucky
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Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
I suspect the RCV is the issue (Refrigerant Control Valve) which is located inside the compressor. Later models have an electronically controlled RCV which is accessible from the outside.

Trivia: My TDI Vanagon (02 Jetta engine in an 84 Van) uses the compressor that come on the engine and everything else is the old R-12 system. I installed all new hoses, flushed the condenser & evaporator, installed a new Dryer, evacuated for almost two hours, installed oil and R-134a. How did I know how much refrigerant to install? Well, I didn't. But, using info gleaned from InterWebbing, my gauges and observing ambient temp, I got it pretty much spot on as it cools awesomely well. Lastly, if you notice the decal under the hood there's a Plus or Minus number in reference to the amount of R-134a to install. If I remember correctly, the variance is about 10% .................... Oh, and I did remove the RCV from the compressor and replaced it with a 7/16 inch bolt and a nut. Thus, it operates like the OE compressor that come on the Van....
 

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Apr 10, 2018
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2003 VW Golf
So I've just started driving it again, auto to 6-speed conversion, and here's what I've found. I have manual climate control and if I keep the fan at 1 and the temp at full cold I seem to have continuously cold air, even when it was 90+ outside. If I move the fan to 2 the air will eventually get warmer, especially sitting at a light but will cool off again. With the fan at 4 the air will warm up after a few minutes and will periodically get a bit cooler but never cold. The drain, cabin filter, and cabin fan are all clean and in good order as well as the radiator fans. The compressor is engaged when it is blowing warm air and the air flow doesn't seem to change. The more I play with it the more I feel like it is just low on refrigerant but I have little to no experience with ac. Thanks for all of the comments so far and hopefully this can shed some light on the situation
 

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Apr 10, 2018
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Houston
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2003 VW Golf
I meant to mention that too, thanks BobnOH. I get a bit of air blowing out of the vents with the fan off so that was one of the first things I checked. The blend doors and the foam look and work like new.
 

Typrus

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Jun 25, 2004
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BCS, TX, USA
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2002 Black Jetta Sedan GLS/TDI 5mt
That does sound likely to be a low charge- insufficient cooling capacity to keep up with higher airflow.
It could still be something else, but that bit of info would tend to tell me low charge.

As for pressures, I had to do another AC job today and as an experiment I charged it to half weight first- pressures came out almost perfect. Recovered and charged to spec, very little change in pressure but noticeable improvement in cooling performance. No, not a VW but a Cat RM500B, however the principle applies. Btw it was 65% and 98*F.
 

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Apr 10, 2018
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Houston
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2003 VW Golf
I'm going to just get it flushed and recharged and see how it plays out. Typrus, thanks for running a quick experiment, that gives me a bit more confidence.
 

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Apr 10, 2018
Location
Houston
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2003 VW Golf
A quick update. I was a bit low on refrigerant, the high pressure port was leaking a bit. However my radiator fans are shutting off when I'm sitting still which causes the compressor to shut off 20-30 seconds later. The fans turn on when I turn on the A/C so I assumed the controller was good after I ran through some high water a while ago that killed my fans.
 

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Apr 10, 2018
Location
Houston
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2003 VW Golf
They charged me for 32oz of refrigerant so im assuming they tried to top it off, found the leak and refilled from empty. The air is colder now so at least i have made some progress and tye fan controller is cheap and easy enough to replace. Ill post an update when i get it in.
 

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Apr 10, 2018
Location
Houston
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2003 VW Golf
Ok, final update. I must be blind because the fuse on the battery for the fan high speed was blown and I know I checked the green one just a couple of day earlier. Sorry for the wait, it took a while to source the metal strip fuse, but everything is working great now. I also replaced the fan control module since I felt like the fans were turning off before the high speeds should kick in, it may have been what blew the fuse I suppose. Thanks to everyone for the input, yall are why I come here first
 

Genesis

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Joined
Feb 26, 2003
Location
Sevier County TN
TDI
'03 Jetta Wagon
Blown high speed fan fuse frequently means you have a fan that's either jamming (locked-rotor, which will blow the fuse) or shorted on high (ditto.) Watch that carefully; it's possible you had something jammed in one of the fans that is now clear but it's also quite possible you have an intermittent, temperature-related short in one of them and if so it will blow again. If it does then both fans have to be considered suspect and I'd change 'em out.
 
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