'81 Air Conditioner Question
Thread Starter
Intermediate
Joined: Mar 2014
Posts: 28
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'81 Air Conditioner Question
Needing help again guys! I'm trying to sort out why my a/c is not working. Does anyone know how to check for power at the compressor? Or rather, how do I check that I'm getting power to the pigtail that connects to the compressor?
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
All you need is an inexpensive test light like a Lisle that is available most everywhere..................
Thread Starter
Intermediate
Joined: Mar 2014
Posts: 28
Likes: 0
Thanks for the reply but not what I'm looking for. I guess I should have explained a little better. The pigtail connecting to the compressor has 2 wires. Is one of these ground or is the compressor picking up ground somewhere else? If I connect my multi-meter to these 2 wires should I be seeing 12 volts? That is with the engine running and the a/c turned on.
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
Thanks for the reply but not what I'm looking for. I guess I should have explained a little better. The pigtail connecting to the compressor has 2 wires. Is one of these ground or is the compressor picking up ground somewhere else? If I connect my multi-meter to these 2 wires should I be seeing 12 volts? That is with the engine running and the a/c turned on.
You should see 12 volts at one wire and a ground at the other wire. You really need a battery-powered test light too. One that lights up when it touches a hot terminal. Only $7.50 or so and available from every auto parts store.
Racer
Joined: Aug 2010
Posts: 337
Likes: 6
St. Jude Donor '16
If there is no freon charge in the system the compressor will not engage,"The compressor cycling switch is a normally closed switch that opens to prevent compressor operation if refrigerant pressure is lost..." page 8A-69, Chevrolet Corvette Shop Manual, 1981...Good Luck!
Thread Starter
Intermediate
Joined: Mar 2014
Posts: 28
Likes: 0
If there is no freon charge in the system the compressor will not engage,"The compressor cycling switch is a normally closed switch that opens to prevent compressor operation if refrigerant pressure is lost..." page 8A-69, Chevrolet Corvette Shop Manual, 1981...Good Luck!
Safety Car
Joined: Jun 2004
Posts: 4,374
Likes: 224
From: Beecher Illinois
As mentioned, low Freon will keep it from running.
In the pic, center right under the black hose you'll see the pressure switch. Pull the plug off and jumper the contacts in the connector.
In the pic, center right under the black hose you'll see the pressure switch. Pull the plug off and jumper the contacts in the connector.
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Melting Slicks
Joined: Jul 2009
Posts: 2,091
Likes: 40
If there is no freon charge in the system the compressor will not engage,"The compressor cycling switch is a normally closed switch that opens to prevent compressor operation if refrigerant pressure is lost..." page 8A-69, Chevrolet Corvette Shop Manual, 1981...Good Luck!
If you have a leaking hose, fitting , etc ......your probably low on freon ...real question is WHY ?..but start by ...buying couple bottles of gas....charge it up see, what happens ...if it works for a while and then the gas leaks out , you know kinda where you stand.
Worst case is there might be is a leak in the condenser or evaporator . Compressor can be damaged from lack of proper care, oil , moisture ...on and on.
Finding the leak can be tricky , if you don't have experience with AC and various techniques for finding freon leaks.
Your system may need evacuating , new suction dryer , oil .....etc.......this is generally above the heads of most shade tree mechanic s. Special tools and equipment is used in AC work.
I would suggest taking it to a competent AC car guy , if your charge does hold .
Last edited by LS4 PILOT; Jun 1, 2015 at 12:04 PM.