| [GMCnet] HVAC gauges and capacitors [message #87376] |
Sat, 05 June 2010 11:35  |
KB
Messages: 1262
Registered: September 2009
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> and the back of the napkin
>
> 1 let out the remaining refrigerant
> 2 slather in 3 cans of duracool (low side) with the engine running
> 3 let it sit till warm (3-4 hours)
> 4 measure the pressure with a tire gauge
> 5 let sit over night, and if the pressure is the same - you are good
> 6 should get cool
thanks Gene, sounds pretty easy.
Karen
1973 23' Patience Tester
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Karen
1975 26'
San Jose, CA
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| Re: [GMCnet] HVAC gauges and capacitors [message #87394 is a reply to message #87376] |
Sat, 05 June 2010 13:53  |
KB
Messages: 1262
Registered: September 2009
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> If you buy one of the inexpensive R-134 installation kits, they come
> with adapters for older R-12 systems (like your GMC has). Once you
> screw on the correct adapter, and only one fits, you will only be able
> to hook up the gauge to the correct side of the system for filling and
> monitoring the pressure on the low side. It's foolproof (sailor proof
> too).
thanks. I think our system was already converted to r-134 by a previous owner,
though I have almost no records of their work.
The AC system has two ports that look rather like schrader valves -- a small one with a blue
cap, and a big one with a pink (faded red?) cap. The receiver-drier has a tag
that indicates it's for use with either r-12 or r-134, so not original.
Is the small port the low side?? And when emptied, should the system be at vacuum, or just empty?
thanks,
Karen
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Karen
1975 26'
San Jose, CA
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| Re: [GMCnet] HVAC gauges and capacitors [message #87413 is a reply to message #87394] |
Sat, 05 June 2010 17:09 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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| KB wrote on Sat, 05 June 2010 14:53 |
Thanks. I think our system was already converted to r-134 by a previous owner, though I have almost no records of their work.
The AC system has two ports that look rather like schrader valves -- a small one with a blue cap, and a big one with a pink (faded red?) cap. The receiver-drier has a tag that indicates it's for use with either r-12 or r-134, so not original.
Is the small port the low side?? And when emptied, should the system be at vacuum, or just empty?
thanks,
Karen
|
Karen,
Yes, the small port is the low (suction) side.
Most systems leak down to 20~50 psi at which point the compressor will(should) not run as it is stopped by the low pressure switch. So, it should have pressure when you poke the schrader valve or put a gauge set on it.
If you are going to recharge with HC-12a, you can just release the existing charge, and let the system pressure down to atmospheric (0 gauge~14.7psia). This practice is not legal, but there is no scientific data to support the rule. This only works with HC-12a as it does not hold any grudge from the years of being ignored.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] HVAC gauges and capacitors [message #87440 is a reply to message #87413] |
Sat, 05 June 2010 18:59 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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>>
>>
>> Is the small port the low side?? And when emptied, should the system be at vacuum, or just empty?
>>
>>
>> thanks,
>> Karen
>
An easy way to tell the low pressure side is to look for the pressure switch that has two wires that go to the compressor clutch. That has a rubber connector on it.
That is attached to the High Pressure side. DO NOT fill using that side. Use the one that doesn't have the pressure switch in the line.
Emery Stora
77 Kingsley
Santa Fe, NM
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