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1996 Chevrolet Astro - Compressor On Then Off

Quarterwave1234 on Wed May 12, 2010 1:25 PM User is offline

Year: 1996
Make: Chevrolet
Model: Astro
Engine Size: 4.3L
Refrigerant Type: 134A
Country of Origin: United States

Hi everyone,

Further to the subject, I'm having some issues with the A/C system in my 1996 Astro van. A while ago, I had an issue with the AC compressor staying ON, which would make the accumulator freeze up - that ended up being a bad relay (the seller I bought the van from had rigged the AC to stay on all the time - presumably from the problem I am having now)....

Fast forward a year or so later, and the problem I have now is that sometimes the compressor will kick on when I turn the switch on the HVAC controls to "on" - but sometimes it will not come on at all.

When it does kick on, I can hear and feel the compressor doing it's thing (engine rpm changes just a bit, and some slight vibration in the steering wheel), and cold air comes from the vent - REALLY cold air.

However, sometimes when I turn the HVAC switch to on, nothing happens - the AC fan will come on, but no cold air.

Ever since I've had the van, I've noticed a loss in power whenever the AC is switched on, along with an accompanying noise - sort of like a groaning noise when the engine is under acceleration, but it's only really audible from inside the cabin - along with a noticeable drop in power from the engine (eg : more gas pedal is needed to accelerate compared to when the AC is off - or when it's not switching on). But, the air is freezing cold when it's working.

Does anyone have any ideas as to what it could be ?

For whatever it's worth - to me (who is not an experienced AC tech), it seems like it is a sensor-type of problem... maybe it's more than that - like the clutches wearing out in the compressor or something - but my gut tells me that it's something to do with actually switching on the compressor....

Thank you in advance for any help.

HVargas on Thu May 13, 2010 12:08 PM User is offlineView users profile

First thing I would do it hook some gauge's up to it to get the pressure readings. The next thing I would do, is when you turn on the compressor and it doesn't engage, I would tap the front hub of the compressor to see if it could just possibly be too large of an air gap on the clutch. Tap it with the butt end of a hammer and see if it kicks on. You could be low on freon and at that point where depending on ambient temperature, the system is right on the line of having enough pressure to kick on the compressor. If it has a low static pressure, then I would find the leak, evacuate it, fix the leak and recharge it with the proper amount. If there are no leaks and pressure's are ok, then I would start looking into the electrical system more. See if the switches are getting power when you turn on the A/C. You may not be getting power to the compressor all the time causing it not to turn on. As far as the compressor going bad and dragging down the engine, the best way to tell will be with pressure readings while the van is running. After that you can pull the orifice tube to check for debris to see if it is coming apart.


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Quarterwave1234 on Thu May 13, 2010 12:54 PM User is offline

Thanks Adam - all of your notes make sense. I'll take it down to the shop soon and have the pressures read and then go from there.

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