Ac quit
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Fleet Owner
Joined: Aug 2004
Posts: 20,419
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From: AZ
Ac quit
Ac quit and all fuses are good. It was working good. I was going to put a can in it but then thought I need the compressor running for that, don’t I? I’ve read you can hot wire it, would that help or hurt? If that would help how do you hot wire it? Thanks
Lead Driver
Joined: Mar 2006
Posts: 5,109
Likes: 1,538
From: western SD
Did the AC just quit, or was it kind of warmer than usual? Did you check wires to the high pressure switch located in the line, just behind the compressor? On my 96 C&C truck, the spade contacts were loose and were loosing contact. If it is low on Freon, there will only be power to one side of the low pressure switch located on the accumulator, and adding a can of it will make the compressor kick on.
Hotshot
Joined: Dec 2005
Posts: 14,377
Likes: 608
From: evansville in
I would get gauges on it and jump low pressure switch on accumulator. I'm just not a proponent of dumping a can in as if it's something else now the level is screwed up along with the original issue.
just my .002.
just my .002.
Lead Driver
Joined: Mar 2006
Posts: 5,109
Likes: 1,538
From: western SD
Agreed. I was just making the point IF it is low on Freon, adding a can will make the compressor kick on if the rest of the system is in operating order.
Thread Starter
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Fleet Owner
Joined: Aug 2004
Posts: 20,419
Likes: 197
From: AZ
Did the AC just quit, or was it kind of warmer than usual? Did you check wires to the high pressure switch located in the line, just behind the compressor? On my 96 C&C truck, the spade contacts were loose and were loosing contact. If it is low on Freon, there will only be power to one side of the low pressure switch located on the accumulator, and adding a can of it will make the compressor kick on.
Might take you up on that Eric. We are in Vegas for a few days so it just depends on when I can get some time. Thanks to all!
Lead Driver
Joined: Mar 2006
Posts: 5,109
Likes: 1,538
From: western SD
A quite easy way to check for low Freon is to unplug the low pressure switch on the accumulator, and jump the two wires in the plug. If the compressor clutch kicks in, you have either a faulty low pressure switch, (unlikely) or low charge. Does the clutch show any signs of over heating? For a test, You could run a wire from the positive post on the battery to the compressor clutch to see if there are problems with the clutch. With the engine off you should be able to hear the clutch snap together when you touch the wire to the clutch wire. but in all reality, until you get your gauges on it we are just guessing.
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Fleet Owner
Joined: Aug 2004
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From: AZ
A quite easy way to check for low Freon is to unplug the low pressure switch on the accumulator, and jump the two wires in the plug. If the compressor clutch kicks in, you have either a faulty low pressure switch, (unlikely) or low charge. Does the clutch show any signs of over heating? For a test, You could run a wire from the positive post on the battery to the compressor clutch to see if there are problems with the clutch. With the engine off you should be able to hear the clutch snap together when you touch the wire to the clutch wire. but in all reality, until you get your gauges on it we are just guessing.
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Lead Driver
Joined: Mar 2006
Posts: 5,109
Likes: 1,538
From: western SD
Sounds like you are on the right track. When you first hook your gauges up, you should see somewhere around 50-60 lbs. on the gauges if the system is charged. Running they should be around 40ish on the low side, and 225-250 on the high side, depending on air temps. It has been a while since I studied the compressor, but usually there is just one wire going to the magnet on the compressor clutch with a spade type connector in it. Separate the wire at the connector, and touch your jumper wire to the wire that runs to the clutch magnet.
Lead Driver
Joined: Sep 2002
Posts: 9,548
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From: North Texas
My money says a leak. His system was just opened when the truck was down for a new bottom end.
If you are in Texas, let me know where and I will diagnose it real quick for you. I work for Miller Lite.
Need to know your ambient temps to give you any idea of system off pressures. I usually sit in the 90-110psi with the system off in the summer. Pressures change with temperature, simple physics.
I posted my full charge head pressures with a seemingly healthy, reman, stock style compressor this summer in my thread as I recalll. I think I had around 45/230 at high idle fully charged. Remember my evap is spotless so is the condenser.
If you are in Texas, let me know where and I will diagnose it real quick for you. I work for Miller Lite.
Need to know your ambient temps to give you any idea of system off pressures. I usually sit in the 90-110psi with the system off in the summer. Pressures change with temperature, simple physics.
I posted my full charge head pressures with a seemingly healthy, reman, stock style compressor this summer in my thread as I recalll. I think I had around 45/230 at high idle fully charged. Remember my evap is spotless so is the condenser.
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Fleet Owner
Joined: Aug 2004
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From: AZ
I have zero pressures, power to the clutch and nothing happens, jump the plug on the low pressure switch and nothing happens. Looking around I found that the dumb a** guy who put the motor in didn't support the wire harness to the alternator and it dropped down and was rubbing on the tensioner. Wore a good size hole in the wiring harness so I cut it open and two wires were bare but not broken. Taped it all up for now, I should be home tomorrow night and will investigate it further. I don't understand the zero pressures unless these gauges of mine got screwed up being in the bottom of my tool box for years. I also would think the clutch would activate regardless of Freon level. Maybe those two wires shorted to each other and caused some real damage?
Tuned
Joined: Apr 2018
Posts: 329
Likes: 17
You're right about the clutch. Pressure doesn't matter if you have 12V across the clutch, it will engage. Pressure switches keep the 12V from getting to the clutch.
Just guessing but there's a good chance your engine swapper didn't use new o-rings in your AC or just threw it together as an afterthought. Look at all the joints for oil accumulation indicating a leak. To be fair, these are old trucks and old AC can leak anytime, anywhere.
Just guessing but there's a good chance your engine swapper didn't use new o-rings in your AC or just threw it together as an afterthought. Look at all the joints for oil accumulation indicating a leak. To be fair, these are old trucks and old AC can leak anytime, anywhere.