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VW Jetta A/C starts slow works fine at speed plus whistling sound inside

gregoron on Thu October 25, 2012 5:23 AM User is offline

Year: 2000
Make: Volkswagen
Model: Jetta GL
Engine Size: 2.0
Refrigerant Type: R134a
Ambient Temp: 86
Pressure Low: 36
Pressure High: 125

My car's A/C starts slow but gets cool when it picks up speed (i.e. above 2k rpm). Once it gets going, it is still cool in traffic. Today, at 86 deg. fahr., I did my readings from my manifold gauge set and it read 36jpsi low, 110 - 125psi high. At 900 rpm, the high reading is 110psi., but it would slowly creep up to 125psi as I increase to 1500rpm and held it there. I know that the high reading is not normal. It should be around 230psi as per my Bentley manual for this model.

I also hear an occasional whistling sound coming from inside the car on the passenger side at idle. I'm assuming it's from the TXV expansion valve and that may well be my problem, but I would like an expert's opinion.

I just installed a new Behr variable displacement compressor, receiver/dryer, expansion valve with new O' rings. Prior to that, it was not working at all. After removing the old parts, I installed the new ones but left them unconnected and covered with their original seals.

I flushed the evaporator, condenser, high & low pressure lines and hoses. I then dried it with compressed air at 90 psi for five minutes each component. I covered the parts and used the car for a week prior to connecting all the parts and hoses together. I then pulled a vacuum for 45 min, which held for 10 minutes at -28psi. I then recharged the system with two 12oz cans of R134a (one can with dye inside). Bentley manual says I need 26 + 1.8 oz of R134a. The new Behr compressor already came with 4.6 oz of PAG oil, enough for the entire system.
One thing I may have done wrong is to turn the cans upside down as I emptied it through my manifold gauge set. I read later that I'm not supposed to do this.

Could my problem be due to a sticking expansion valve, moisture in the system, undercharge, or all of the above? I hope it's not the new compressor. I can turn the inner wheel with some resistance when engine is stopped - although it's not as smooth as it was when it was new. Both fans (radiator & condenser) are working also.

Any help would be appreciated.

Edit: PS, I checked Static Pressure with engine cold at 76 deg. and it was 83psi.

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2000 VW Jetta GL 2.0 5 spd.

Edited: Thu October 25, 2012 at 8:07 AM by gregoron

TRB on Thu October 25, 2012 3:57 PM User is offlineView users profile

Get a OEM expansion valve. There has been a bad run in the aftermarket industry on these valves for the past year and a half.

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Contact: ACKits.com

gregoron on Thu October 25, 2012 7:01 PM User is offline

A mechanic told me that it might be the compressor. I was really hoping not as it is new.

I did some readings again and at 90 ambient, I got 35 low and 150 high. Temp from the air duct is 70 deg. I tapped the TXV and no effect. I still hear whistling inside car but not outside near TXV. After driving for a while, duct temp would go down to 50.

Is it the variable compressor or TXV? Should I go to a shop and have them evac and recharge just in case there's moisture?

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2000 VW Jetta GL 2.0 5 spd.

TRB on Thu October 25, 2012 10:19 PM User is offlineView users profile

You symptoms are what I have seen concerning these bad valves. You can swap out compressors as we have to no avail, or swap out the cheaper item first and see what happens. But do not swap out the valve with another after market valve. We will not even list the after market valve on our site and thus the reason it looks to so much more in cost.

-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

gregoron on Fri October 26, 2012 11:49 AM User is offline

Thanks for your input. I'll go ahead and have a pro replace the TXV with OEM part. Better to have a machine put in the right amount if refrigerant in there than guesstimate with cans. Any harm if I run my AC with faulty TXV?

Edit: what is the part number of the OEM TXV for this car at this site?

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2000 VW Jetta GL 2.0 5 spd.

Edited: Fri October 26, 2012 at 11:53 AM by gregoron

gregoron on Mon October 29, 2012 3:19 AM User is offline

took my Jetta to an a/c repair shop and sure enough it was a defective expansion valve and a low charge. He replaced the TXV, pulled vacuum, then recharged to right amount. Now it blows cold air - 45 to 50 deg at the center vent. My DIY would've been less costly if it weren't for this defective part that I'm returning. Lesson learned - buy OEM or test first. Thanks for the help.

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2000 VW Jetta GL 2.0 5 spd.

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