Auto AC question

[Simplespeed]

I didnt want to bring this question here because this is not an auto diagnostic forum. I have a VW so iv posted question on VWVortex.com but all i get is "take it to a professional". I know there is alot of knowledge and do it your selfers here so i tough id give it a shot.

2003 VW Golf GTI 1.8t
The system is properly charged and holds pressure, the compressor kicks on and off when the AC button is pressed and it cycles. There are no AC lines under the hood that are cold to the touch. I was blowing very cold and then slowly started getting warmer over the course of 3 weeks, now its gone. And its really hot down here in Texas.

Thanks in advance for any help.

 

[MechanicNamedJohn]

Check the low side lines at the accumulator. A lot of the times this is the problem. You may have one cold and the other not "both are low side." All low side "the big line" lines should be cold, the high is not.

 

[Busted_Knuckles]

Sounds like you lost some of your charge, what kind of cycle times do you have as far as "on" and "off" are we talking running "on" (compressor clutch engaged, pump turning) for seconds and "off" for minutes or running "on" for minutes and "off" for minutes ?

 

[Falcon67]

Lost charge or expansion valve not working.

 

[Simplespeed]

The compressor will cycle on for a few minutes at a time. Which of these is the accumulator? I cannot find any cold lines anywhere.

 

[MrMark]

Study this to see what type of system you have. That can is either a receiver/dryer or an accumulator. It depends on your system as to where it is located in the AC system.

http://www.familycar.com/Classroom/ac1.htm

You may have a receiver/dryer on the high side in front of an expansion valve at the evaporator. Is that can on the high or low side? You need to trace out your lines to see where everything is coming from and going to. Condensor is right in front of the radiator, it looks like a mini radiator. Compressor you know. Evaporator you won't be able to see, it is under the dash probably, looks like another radiator, it is where the cooling happens by expansion of high pressure liquid to low pressure gas, as liquid boils at 40 degrees or so and vaporizes thereby absorbing heat from the air blowing across the cooling fins of the evaporator.

I don't know your VW setup.

 

[Simplespeed]

The small can on the top is on the low side and i think is the accumulator, the bigger can on the bottom is on the high side and is the dryer.

 

[lsrx101]

The small can on the top is on the low side and i think is the accumulator, the bigger can on the bottom is on the high side and is the dryer.

Not quite. It won't have both an accumulator and receiver/dryer. The can on the bottom is the receiver/dryer and the can on top is a muffler with a service port attached.
Hard to tell without a wider view, but that looks like the High Side service port. That would make sense as mufflers are usually located in the compressor discharge line.

 

[Simplespeed]

Not quite. It won't have both an accumulator and receiver/dryer. The can on the bottom is the receiver/dryer and the can on top is a muffler with a service port attached.
Hard to tell without a wider view, but that looks like the High Side service port. That would make sense as mufflers are usually located in the compressor discharge line.

I will do a double check tomorrow and see what line it is. Im learning alot about ac today lol.

 

[burleymike]

Did compressor cycle on and off frequently or when you would turn it on the compressor would stay on? If it would stay on it is likely a variable displacement compressor, the control valve can go bad on these and make the compressor act like it is not pumping. You really need to connect some gauges so we know what is happening.

 

[jm1fd]

First off, how do you know for a fact that it is properly charged?

Secondly, can you get pressure readings from the high and low sides? That would help a lot....

My money is on bad expansion valve. The frequent cycling is because LOADS of pressure is building up against the shut valve, and the high pressure safety switch is cutting off the compressor. Pressure readings would help confirm.

 

[Falcon67]

I'll add lunched compressor vanes to the possibles too. Been there, if the pump vane seals wear out, they typically fill the system with trash and it all stops working. Compressor will still go round and round but do nothing. Debris chokes up the expansion valve, dryer, etc.

 

[stephen4785]

VW have 2 electric fans in front. One for the radiator and one for the condenser. Make sure that the condenser fan is coming on when your a/c is running. The fan wont stay on all of the time, it will just come one for a mintue and then shut off which is normal. If the fan is working properly you need to see what you pressures and post them. Im betting that there's a leak in the system but if the system is properly charged then Id suspect the expansion valve is stuck which happens on VW's alot.
VW certified (dealer tech)
ASE Automotive Master certified
ASE Truck Master certified

 

[stephen4785]

The compressor will cycle on for a few minutes at a time. Which of these is the accumulator? I cannot find any cold lines anywhere.

The receiver drier is the one on the bottom, the one on top is a muffler and the port is the low pressure service port.

 

[jay50]

I'll add lunched compressor vanes to the possibles too. Been there, if the pump vane seals wear out, they typically fill the system with trash and it all stops working. Compressor will still go round and round but do nothing. Debris chokes up the expansion valve, dryer, etc.

also condensor is full of **** and will need to be replaced if compressor puked out it's guts

 

[sdowney717]

cycling when its hot out means the charge is low
In hot weather it will never shut the compressor off.
The cycling effect is the low pressure cut off switch activating. With a full charge in hot weather, the low side pressure never drops low enough to shut off compressor.
The low pressure switch helps protect compressor from low charge low oil condition so it wont burn up.

Typically if you cant find any leaks you might have a leaky evaporator core under the dash. That thin aluminum rots when moisture gets into the system forms acids when mixed with PAG oils.
My daughters jeep had such a leak. You could also faintly smell it in the car.
I used qwest super seal and it is holding. Charge would typically go in a month.
If the system is dry, the super seal is ok. Wet systems will cause troubles using it.

 

[Gus_Mahn]

Some VW use a variable displacement compressor. It makes it very easy to overcharge if trying to partial charge. It's best to charge variable displacement compressors a full charge by weight after evacuation.

The accumulator/drier is the one on the bottom. I'd say the one on the top is a muffler.