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Silverado A/C Out - Short Cycling

traderyoda on Sat June 12, 2010 4:36 PM User is offline

Year: 1999
Make: Chevy
Model: Silverado 1500
Engine Size: 4.3L
Refrigerant Type: 134a
Ambient Temp: 75
Pressure Low: 35
Country of Origin: United States

This is the first problem I've had with my Silverado's AC. Last year the compressor or the clutch was rattling a bit so I wasn't surprised when it didn't work this season. The clutch was short cycling - it will engage and kick out after a few seconds; compressor not turning. I figured - okay, I've got a leak... probably took a stone in the condenser. I only have a low pressure gauge so I hooked it up and read a static pressure of around 35 psi at the low pressure port. That didn't seem low enough to prevent the compressor from starting, but just to be sure I tapped in a can of 134a, started the engine, and let the pressure build a little to see if the low pressure switch would kick in - no joy. I didn't want to overcharge, but now the static pressure is 55 psi with the engine off and I can't get the compressor started. What's next? Replace low pressure switch?

jgcox6 on Mon June 14, 2010 5:07 PM User is offline

you might have overcharged your system with that 55 reading...but have you tried tapping the front of the clutch with a hammer handle or something (be careful not to get hit by the fan or anything) If the clutch pulls in...then your air gap has gotten too far..

mikey71174 on Mon June 14, 2010 6:49 PM User is offline

I've personnally seen this problem in serveral chevy models, to include a Lumina that I had. In every one, the compressor needed to be replaced.

mk378 on Mon June 14, 2010 6:58 PM User is offline

A pressure of 35 static on a warm day means that the system is nearly empty. When you have a leaky GM, odds are it's the compressor but of course nothing is certain.

JACK ADAMS on Mon June 14, 2010 7:34 PM User is offline

You say static pressure when off is 55psi, which means you have a leak but will also need the high side pressure with a real set of gauges to be sure. The most common places for this model to leak are the case seals and the discharge line. You will be best to have the system leak check first then repair. Nothing is certain till this is done.

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