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Is my compressor bad?

OFilippov on Thu June 23, 2011 7:28 PM User is offline

Year: 1999
Make: Pontiac
Model: Firebird
Engine Size: 3.8
Refrigerant Type: R134A
Ambient Temp: 90
Pressure Low: 30
Pressure High: 120
Country of Origin: United States

Hey guys - '99 Pontiac Firebird here.
I think my compressor is bad, but wanna see what your thoughts are before I start shopping for one.

My AC started to work bad so I found a leak - got it fixed, pull the vacuum and tried to charge the system.
I hooked up my gauges and getting readings at about 30 on low side and only 120 on high.
When I open the low side knob on the gauges for charging the low side reading goes up but high side stays at 120. When I close the low side the pressure goes down to 30 with the high side still at 120.
Compressor is working at all those times (clutch engaged). Also I think my compressor is a bit noisy - checked it with mechanic's stethoscope.

So what are your thoughts - bad compressor or clogged condenser/lines

PS got to fix it quick - it is getting close to a 100 down here in Florida.

mk378 on Thu June 23, 2011 8:03 PM User is offline

It's a variable compressor. Need to get a full charge in (by weight) to know what you have. What you are experiencing appears normal for an undercharged variable displacement system.

The indicated pressure on the low side goes up due to resistance in the hoses and service port while refrigerant is flowing out of the can. Open the valve and let it flow until you have a full charge by weight.

OFilippov on Fri June 24, 2011 4:36 AM User is offline

Thanks for a reply, but maybe I didn't explain it right - it doesn't wanna charge - the needle stuck at about 120 - I had a valve open for quite some time but still feels like compressor not pumping a freon to the high side.

OFilippov on Sun July 10, 2011 10:59 PM User is offline

Hey guys - me again.

This is what I've done so far.
I've changed almost everything in my A/C system: Compressor / Condenser / Accumulator / Orifice Tube / Air Conditioner Evaporator Tube(the one that goes from condenser to evaporator) and all seals - all new. The only old parts are 2 tubes that goes from Compressor to Condenser and Compressor to Accumulator, and Evaporator are still my old ones. I got those flashed with Four Seasons 69991 Dura II Flush Solvent.
I put 9oz of PAG-46 oil (that what sticker on a new compressor said to use) about half in compressor and half in accumulator and assembled everything together. Pull the vacuum, closed the valves on my gauges and let it sit for about 30 min - the needles still showed the perfect vacuum so I am sure that I don't have any leaks. Then I opened both valves and pull the vacuum again for about 50min and closed both valves.

Now trying to charge the system:
Put my tank of R134-A on the digital scale. Hooked up the yellow hose from the gauges to it and purged all air from the hose. Opened both valves on the gauges and let the system take as much freon as it can (about 0.22lb). Closed both valves.
Started the car, put A/C on max and got rpms to about 1500.
The clutch didn't kick in for some reason. I didn't wanna find that problem at this time so I decided to manually turn the clutch on. Removed relay and shorted contacts with the paper clip. Got the clutch on.
Trying to charge - opened the low side valve - see the low side gauge goes up, but nothing gets on the high side again! Let it sit like that for couple of min - still no changes on the gauges nor the scale.

What am I missing here?

PS Found the problem - My low side coupler on the gauges got clogged or something happened to it - I don't know. Nothing was going through it. I even connected it to a compressor trying to blow it through - nothing. Had to order a new one.

Edited: Mon July 11, 2011 at 9:12 PM by OFilippov

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