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Help with 96 Suburban

JoeH on Fri April 11, 2008 12:39 PM User is offline

Year: 1996
Make: GMC
Model: Suburban
Engine Size: 5.7
Refrigerant Type: r134a
Ambient Temp: 72
Pressure Low: 20
Pressure High: 120

Long story... Back in Nov of 07 I recharged the A/C since the compressor was cycling a bit, and the next day most of what I had put in was gone. I've had to keep putting more refrigerant in for about a year now to get the a/c somewhat working. March of last year there was no freon in it at all. Filled with 60oz of freon. The pressure reading I have posted here are after putting 3 cans in the system. Before placing those 3 cans in, the pressure was only at 20psi. Compressor was replaced about 4-5 years ago with a new offmarket HT6. Not sure what brand. Sounds like marbles rolling around in it when it runs. Replaced at the same time was the accumulator, manifold, condensor, and oriffice. There are some areas of dried oil on the manifold crimp connections, but cannot find a leak anywhere. Tried squirting soapy water on all the fittings and still nothing.

So my question is this. Is there some other way to see if my compressor is working correctly, and is there another way to find where the system might be leaking? The truck has dual air and the rear air has always blown colder than the front. Gotta get this fixed soon since summer is almost here.


bohica2xo on Fri April 11, 2008 1:12 PM User is offline

With a leak that large, and the repeated top-offs there is likely little or no oil in the system now.

A lot of plumbing on those trucks, as well as the usual leak spots. Since your compressor is already putting trash in your system, I would be inclined to add 6 to 8 ounces of oil, some dye & run it with the big leak just long enough to find the leak.

I would then plan on replacing the condensor, accumulator, orifice tube, compressor & any line with a muffler.

You will need to pull the rear TXV for inspection, and thoroughly flush all of the hard lines on the system. Both evaporators should be flushed & cleaned to bare metal - or replaced if you don't have that capability.




Front Evaporator

Rear Evaporator

After it is clean, with a new compressor & condensor you can charge the correct quantity of oil & evacuate it before charging.

Then it will cool just like it did when it left the assembly line.


"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

GM Tech on Fri April 11, 2008 2:51 PM User is offline

Is this a rear air burban? I'd look for the rear lines to be corroded and leaky if it is... also front evap is highly suspect- I have changed a few suburban front evaps for leaks- a good sniffer will confirm a leaky evap- very easily- since your leak is so big.....

The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

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