1999 Other Volkswagen Models poor cooling

RUNDAWG

MEMBER
1999 VOLKSWAGEN
4 CYL
FWD
MANUAL
11,000 MILES

I have a 1999 VW Cabrio. Car is cooling, but not as well a before. Inspection of the A/C system doesn't reveal any obvious leaks. Air out the vents is only 65 deg. High side pressure is 235 psi and low side is 67 psi @ 1500 rpm. When the radiator electric fan kicks on the High side drops to 190 psi and Low side stays at 67psi. Conditions : OAT 81 deg. Dry bulb, 74 deg. Wet bulb, and 74% RH. The low side seems high, but I can't confirm that as I don't have any manufacture numbers.
I was thinking the low side should be around 25-35 psi. The high side appears to be close to normal (which I think is about 200-225psi). This system has never been touched since the day it was new, so it hasn't been overcharged by some tech. Any thoughts on this system would be appreciated.

3 Replies

2CARPRO JACK

MECHANIC
11,533 POSTS

You are correct, the low side is too high. Is this an expansion valve system? If so the problem may be that it is plugged or not working properly

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Wednesday, August 6th, 2008 AT 7:44 AM

RUNDAWG

MEMBER
7 POSTS

No I don't think it is an expansion valve. I was hoping someone would have a VW manual for that model year, that would confirm it. It appears to be a fixed metering device, which would lead me to believe there is a restriction possibly in the suction line after the service port, down stream of the evaporator and before the compressor. Is there normally any other filters on the one-piece molded suction line that could cause a restriction? Then again, if that was the case, wouldn't the liquid line(head pressure) pressure be low? What suction pressure is normal when the system is operating properly? Thanks.