AC Question

[deadbeat]

I have a 1997 K1500 5.7 Vortec and I noticed my A/C is warm at idle. I bought some gauges and at 80 degrees outside I get 60 degree air at the vents. My pressure on low side at idle was 42 -45 and my high side was 125. If I rev the engine up the air gets cold and the low side drops to mid 30's and high side goes up. One thing I have noticed is at idle the compressor never kicks out, meaning, the clutch stays engaged the whole time. What else should I check before I put a new compressor/drier/orfice tube on it. I have a new vacuum pump to charge it back up correct but I am not sure what it needs. I know the high pressure is low and the low pressure is a little high. There are no leaks and no freon has been added in the 2.5 years I have owned the truck. I have not noticed it freezing up driving it yesterday with the air on for over an hour.

 

[BIG_KID]

Seems to me your headed in the right direction.

 

[90halfton]

Have you checked to see if the condenser/ radiator are plugged up? Lack of air movement through condenser fins can keep it from blowing cold. Until you rev it up and the fan pulls harder, or when moving down the road.

 

[deadbeat]

They are very clean.

 

[streetperf]

I have a 1997 K1500 5.7 Vortec and I noticed my A/C is warm at idle. I bought some gauges and at 80 degrees outside I get 60 degree air at the vents. My pressure on low side at idle was 42 -45 and my high side was 125. If I rev the engine up the air gets cold and the low side drops to mid 30's and high side goes up. One thing I have noticed is at idle the compressor never kicks out, meaning, the clutch stays engaged the whole time. What else should I check before I put a new compressor/drier/orfice tube on it. I have a new vacuum pump to charge it back up correct but I am not sure what it needs. I know the high pressure is low and the low pressure is a little high. There are no leaks and no freon has been added in the 2.5 years I have owned the truck. I have not noticed it freezing up driving it yesterday with the air on for over an hour.

have you tested the fan clutch? If you aren't pulling air through the condenser it can not cool. Seeing as you stated going down the road it's cool. That tells me you are forcing air through the condenser. Put a fan in front of the condenser at idle and see if the pressures change and the temp lowers. If so that tells you the air is not going through the condenser, thus fan clutch not engaging.
You have some strange pressures, you may want to evauate and remove the orfice tube and see if the compressor is wearing out. A charcoal color on the inside of the connections indicates wear from the teflon rings in the compressor. Start from basics and go from there.

 

[barry_g]

Hey,
I rebuilt my own on my 1996.
the pumps fail was on a the sucker side.. figured I'd be gutting the whole thing to air/water pollutants..
orifice tube, condensor, acumulator etc..

My first run after repair, full vacuum refill.. same thing as yours is doing.
At 42-45 the pump sure gets warm...but keeps running. not very cold A/C
The second refill for the next summer, It plucked out a teaspoon of the miracle goops from previous years on the high side.
Upon refill the low side is now 25psi, ice freaking cold.. even the pump stays cool.

38F at the vent...90 outside.

Try a refill with real dupont and no additives.
these are big systems, I really like it.

Also, the original pumps, they got some problems in the casting.
buy brand new (not expensive) under the new standards. either iso9001/2008 or ts16949.

 

[SAATR]

Evacuate and recharge the system to spec. It does sound like a potentially weak compressor, but trying to gauge system health without verifying proper charge is guesswork at best. Ambient temperature will also affect suction and discharge pressures to a huge extent. Verify your charge, run the system until pressures stabilize, and then consult available pressure vs temperature charts for R134a to see where you are relative to where you should be. High suction side pressure with low discharge pressure is usually a bad compressor, but could be a failed/blown out orifice tube in rare cases.

Sent from my XT1585 using Tapatalk

 

[deadbeat]

Got a ton of information, thanks for the replies. I think since my compressor is a little noisy I'll replace it since I need to evacuate the system anyways. I have one of the fans/clutch with more blades, I think 11, I'll put it on as well. A new dryer and orfice tube and charge it to spec and see where I am at then.