AC Help Needed

[publicmsu]

I have a 2000 Grand Prix and AC has been slowly but surely failing, now it doesn't get all that cold, and only feels cold if you hold your hand right at the vent.

I did some diagnostics on the HVAC system - I did find that I have a current / history code 105 - 05 or 105 LH Electric Actuator Open or Short. This I will look into, but do not think it's causing the problem with the AC. Both driver / passenger sides are spitting out warm air.

I did use the manifold gauges and measured the high and low pressure at 2000rpm. Per the vehicle specifications, low pressure is supposed to be at 42 and high at 320. The R134a gauge for the low pressure was around 22-23 and the high pressure would shoot up to 400 and then come back down to 200.

I tried to recharge the system, but after adding two cans, there was no change in either high or low pressure. Does anyone have any additional thoughts on this issue?

[SsHaDyGt]

Does the compressor clutch engage when the AC is turned on?

[publicmsu]

Originally Posted by SsHaDyGt

Does the compressor clutch engage when the AC is turned on?

I do hear the click of the compressor engaging when I go from ECON to 60' AC. I've also verified that the air being pushed out when the compressor is on is considerably cooler than that of ECON. Here in Austin, it's pretty easy to get warm air to come in using the 'vent' setting.

[richtazz]

With the spike in pressure on the high side, it sounds as if you have a restriction such as a partially blocked condenser or accumulator, or a bad variable orifice valve in the compressor (which is a fairly common problem on the V-5 compressors).

[publicmsu]

Originally Posted by richtazz

With the spike in pressure on the high side, it sounds as if you have a restriction such as a partially blocked condenser or accumulator, or a bad variable orifice valve in the compressor (which is a fairly common problem on the V-5 compressors).

Is there something else I should be looking for to verify that the compressor might be shot? Is this orifice valve inside of the compressor or is this the orifice tube? Any other quick diagnostics that could be done to possibly verify that? Is the 200psi a safe shutdown?

Pressures do equalize at ~100 when the vehicle is off.

From what I read, on the 3.8L engine, the low pressure should be 42 and high 320. I've read other threads that suggest 25 is correct, but not sure where these numbers were found.

[richtazz]

System pressures vary with both ambient temperatures and humidity, so you need to adjust your figures to account for these variations.

The valve I mentioned is on the compressor itself. Here's a link to a picture of the valve from Delco's website. Delco part #15-5452 (GM# 2724790)

http://198.208.187.182/internet/View...Number=15-5452

It mounts in the body of the compressor and is held in place by the snap ring shown.

[publicmsu]

Originally Posted by richtazz

System pressures vary with both ambient temperatures and humidity, so you need to adjust your figures to account for these variations.

The valve I mentioned is on the compressor itself. Here's a link to a picture of the valve from Delco's website. Delco part #15-5452 (GM# 2724790)

http://198.208.187.182/internet/View...Number=15-5452

It mounts in the body of the compressor and is held in place by the snap ring shown.

Is this also referred to as the RCV (Refrigerant Control Valve)? The price looks to be ~75$. Now I need to decide if I want to try that and hope that it works, or go for a full compressor replacement, which will run about 200 for the entire kit. Hrmmmm. Wishing there was some way to verify the functionality of that valve.