A/C question. Need help identifying if I have a blockage or a faulty compressor

[supramkivtt2jz]

I have a 2002 Pathfinder with automatic/digital A/C.

So my A/C sucks. When i put it at max blower, forward vents, recirculation, auto, and 65 F, the air is usually warmer than it is outside regardless of the temp. Ive been looking at the service manual and ive followed it as closely as i can. I performed the digital diagnostic and all my actuators and sensors seem to be functioning fine (except the temps they are reading are in the 90-105 range which is what it feels like in the cabin).

I attached gauges the other day. It was 78 F out at 74% humidity.

With the engine running for 10 mins at the above conditions specified in the manual, i get 109 psi on the low side and 125 psi on the high side. Factory Specs for that temp/humidity range are 25-36 psi on the low side and 178-237 psi on the high side. I obviously have a problem.





The manual states replace the compressor if there is a high low side and low high side if 1) both sides equalize after the compressor stops or 2) there is no temperature difference between high and low pressure sides.

Heres my situation:
1) Both sides do not equalize after stopping. It seems that everything holds pressure and there is no leaks in the system even at the compressor.
2) Im not sure how to read the temperature of both high and low sides. The gauges I was using has a temperature reading on it, but I dont know how accurate that is. If it is accurate, the low side was 92 F and the high was about 104 F.
3) To make things REALLY confusing when i switch it to defrost mode and 65 F on the A/C controller the air coming out of the top vents seems to be in the mid 70s F range. Why in the world would the defrost be cooler than the front vents?

It seems that I need to replace my compressor but the defrost situation is very confusing. I would assume if both sides are so close in pressure that there would not be any cooling effect. I returned the gauges before I could take a pressure reading with the defrost mode. Can anyone confirm for me that I need to replace the the compressor (as well as the drier and expansion valve) or could this be a simple blockage somewhere else?

[yeldogt]

Will not they both be low if the charge is insufficient?

I would not open up the systems or do any work without having someone who knows AC systems look at the car. Once opened it will need a new Receiver/ dryer ... I would never replace a compressor without checking fully.

[supramkivtt2jz]

Huh? Yea there would be a low pressure problem on both sides if the charge was an issue but that's not my case. And yes, I will be replacing each component as needed. I'll pay to evacuate the ac, but I'm replacing and recharging everything myself.

[yeldogt]

Sorry .... read the post incorrectly. I see you low side is high. How can someone evacuate the system and you recharge it?

I had a hose fail on Jaguar last summer -- the labor to replace the house and the R/D and 134 charge cost was a bit over $200.00. At the dealer. Maybe you have all the proper equipment --this is one item I leave to those with all the equipment.

Did you try and charge the system/ I only ask .. because I had a similar situation years ago on a car when it had a dirty orifice. It was a cadillac -- the dealer charged it and told me it was the compressor ... I think at the time the cost was $1800.00 -- a local AC shop cleaned it all out and recharged for about $300.00.

It could be the compressor -- but the proper unit is expensive.

[supramkivtt2jz]

yea my low side is waaaaay above specification and the high side is below specification. the service manual give two conditions this would happen and both result in replacement of the compressor. I guess what Im saying is that I believe my ac system does not exhibit either of the two the required conditions.

after evacuating the system you can replace whatever you need and refill with the amount of oil removed from the system. all i have to do is rent a vacuum (autozone) and make sure it holds a vacuum for an hour. once it's good to go i can add 1 lb (vehicle specification) of r134 by weighing bottles.

adding more r134 to the system is dangerous since the low side is already over pressurized. it sounds like your case was high pressure on the high side and a low pressure on the low side.

anway, im wondering if a stuck open expansion valve with a blocked evaporator core could give me the same readings.

[BubbaFL]

Was the compressor clutch engaged when you took those readings?

Either the compressor wasn't running, or it is blown and needs to be replaced.