AC Gremlins

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astrojohn
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AC Gremlins

Post by astrojohn »

I have a 2002 Astro AWD, only 130,000 miles. I've had it for a couple years now, and the air conditioning has worked. This spring, I thought I'd turn it on, to see if it worked. To my surprise, it didn't. The compressor wouldn't kick in.
I put my gauge on it, and it showed there was R134-A in it. So I jumpered across the low pressure switch, to see if it would kick on.
It wouldn't do that. So following the schematic, I checked the 3 fuses, that have anything to do with the ac, and all were fine.
I checked the relays, and even swapped them around, and all were functioning fine. I even did a continuity check on the high pressure switch, and that was fine. I pulled the HVAC control out, and checked to see if the switch was fine, and it was.
So, not knowing what else to do, I jumpered across the low pressure switch again, this time forcing the small wire down into the plug in.
Low and behold, the compressor kicked in. It kept cycling on and off, even on max ac, so I added a can of refrigerant.
The accumulator immediately frosted up, and I thought good.
As soon as the refrigerant ran out, in the can, the accumulator warmed up, and no more cold air.
I tried it with another can of refrigerant, and the same thing happened.
I know I only have the single gauge, which goes on the low side, but the system does have pressure.
I'm no guru on ac, so I'm asking, what is going on? The ac compressor kicks on, but cycles on and off, and I don't get any cold air.
I've never had any experience with in line filter, so not sure if that is plugged. I even crawled under the dash on the passenger side, and while switching the HVAC control around, watched the door seem to be opening and closing.
I like to do my own repairs, and would like to do this one too, except for recharging the ac though.
Can anyone help me out here, and steer me down the right path to success? Miss my ac, and want it back :-k

rpjn59
I am merely driving my van
I am merely driving my van
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Re: AC Gremlins

Post by rpjn59 »

Wow, I was researching a/c problems and solutions to diagnose my own a/c problems. I came across your question here and felt bad that no one responded to your plea. So, what did you end up figuring out was the problem with your a/c system?

Ray
04 Astro
Passenger

Astrophysics
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Re: AC Gremlins

Post by Astrophysics »

Hi,

I bought Yellow Jacket manifold AC gauge kit on Amazon, $118, plus r134a quick adapters $17

So AC system is tricky.

A n Astro front single front AC holds 32 ounces of refrigerant.
Dual air ac with rear ac total 48 ounces.

The problem is that we need to have a pro shop evacuate the old refrigerant and also suck out the moisture with 3 to 5 cfm vacuum pump. The using a accurate food scale with can of r134a on the scale, carefully add the correct amount

At about 85 deg F and 60 % humidity,

Low side gauge should be about 29 to 35 psi and high side about 195 to 235 psi.

It is tricky since too much refrigerant can cause it not to work.

Mine is not working either

I have 62 psi low side and only 105 psi high side



AP

Astrophysics
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Re: AC Gremlins

Post by Astrophysics »

Photo
Attachments
Manifold ac gauges
Manifold ac gauges

Bret Schmerker
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Re: AC Gremlins

Post by Bret Schmerker »

:-k @Astrophysics Gotta be a leak somewhere in the system, in addition to at least one clog in the refrigerant loop. I know that my M11006 has a compromised return line to the accumulator -- abraded aluminum on the inside of the line from the rear evaporator where the fuel lines to the injector assembly bend around the back of the cylinder block -- verified it when I replaced an ignition coil to rule it out as the cause of a single-cylinder miss at idle. Need to replace that return hose assembly and rule out further breaches in the refrigerant loops before I send it to HVAC to recharge the system -- I don't want to seize a second compressor.
1997 GMC M11006 (Safari SLE, 2WD, V6-4300/4L60-E/7.625" 3.73:1 open)
Acquired Jul 2018 / In service Sep 2018 - present
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