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AC has me stumped

Old 06-16-2010, 04:45 PM
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Default AC has me stumped

Having a major problem with my AC/Compressor. I have a 1998 1500 Shortbed 4x4 Z71 with a 5.7 V8, Automatic, System is using R-134 and the AC Clutch wont engage at this time.

A little history on what I have done. I replaced the Engine and Transmission 2 months ago but did not disconnect the Compressor or any of the AC lines. I made sure that all of the AC components were not bent or any undue pressure placed on them during this retrofit. Noticed that the Original AC Clutch was not engaging or disengaging so I replaced the clutch and the unit still wont engage. Unfortunately I didn't check the Freon level before I replaced the clutch since I didn't think about it and didn't have a set of gauge's at the time (not to smart I know, should have known better).

Invested in a set of gauge's and put those on and I have 28/PSI on the low end and the HIGH side reads 25/PSI under load and when checked several hours later. Sight Glass on Gauge Set isn't showing streaking or anything abnormal that I can tell (BUT NOT AN EXPERIENCED AC GUY).

I've checked the fuses, fused links, Relays (Swapped the Starter n AC relay as they are the same in the Engine compartment Relay box) also AC Button on Dash lights up (so I'm figuring that its Ok but I haven't pulled the dash apart to check with a meter), then jumped the AC Clutch connection with a Fusible jumper wire and the New Clutch does engage but when it's connected back to the original connectors I've got nothing. So at this time I'm hoping that someone out there in Chevy Land can give me some insight as to what I'm obviously missing.

Also if someone can give me some insight as to the possibility/or if its possible to bypass the relay at the Engine Compartment Relay Box to engage the Clutch to test the Overall Charge on System (figure the Clutch must be engaged to get accurate reading on the Gauges) that would be greatly appreciated.

Also not an Expert on the AC stuff so I'm under the impression that even though the AC Clutch is not engaging that because the System is under pressure I should be getting a more Normal High Pressure reading (320/PSI) vs the (25/PSI) That the High Pressure side Gauge is showing but if this isn't true let me know.

Thanks in advance for any assistance or help that you can provide as I'm on limited funds right now and hope that one of you out there has the experience or background to help me figure this one out. Thanks Again!!
Old 06-16-2010, 06:44 PM
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So here is an update to my AC issue - I went back and put a Jumper wire from the Battery to the AC Clutch connection while checking the charge with the engine running and the Low Pressure was only at 20/PSI so I added more R-134 and the pressure went up to 28/PSI and now the HIGH PRESSURE is at 105/PSI vs the 25/PSI that it was at prior.

So now the AC Clutch is engaging when the DASH button is pushed down (Light is on Button) and disengaging when turned off so that's the Good news. The BAD news is the Air blowing out of the Vents is still warm and neither of the AC HOSES in the Engine Compartment is COOL to the touch as well as the HIGH side pressure is still only at 105/PSI vs the 320/PSI that it should be.

Any advice/direction or feedback would be greatly appreciated. Thanks again for taking the time to read my posting!
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