Engine Size: 3.8
Refrigerant Type: 134a
Ambient Temp: 95
Pressure Low: 45
Pressure High: 155
I might regret starting this thread at 1am after a frustrating search all night (a bit blurry eyed).
Here's the quick history: This was a 1 owner car, has 120k, never had AC service before. Was working fine, System had leaked out down to ~10psi (loose cond line) after months of setting due to engine probs. Vac'd, recharged, blew cold for a couple of weeks. Leaked down again, replaced all o rings, vac'd, recharged, added leak dye, found comp leak,
replaced compressor (used) after finding external rear case leak (never had any noise from comp). Vac'd, start recharge-
The suction pressure was high before, but it blew cold enough so I didn't care. I am still experiencing high low side pressure 40psi at idle after only 1 can of charge that increases with RPM to around 50+ at 2000 rpm, back to idle pressure goes down to ~35 then settles at steady 40. All the while Hi side is steady about 155 psi.
This should be enough to get the ball rolling on what to ck next.
I may be wrong but don't you have the variable displacement compressor? (V5) If so, I would look at the control valve in the rear of the compressor. Will look this up later if I can get a chance.
V-5 indeed..you need the proper refrigerant amount in it, before you quote any pressures... 1 can is only less than half the requirement......
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......
Yes It's the V5. I had the same pressure issue with the old compressor as the new one.
The more 134 I add the higher the low side pressure goes. With a full 28-30 oz charge the low side was ~60psi before compressor change.
I didn't think it normal to have increasing low side pressure with increasing RPM.
I saw a troubleshooting chart that said high suction pressure could be an open TXV, but this car has an orifice tube.
Edited: Sat August 14, 2010 at 3:45 PM by jga2z
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