I didn't know I was on so many ignore lists 
AC help please
Thread Starter
Melting Slicks
Joined: May 2002
Posts: 2,431
Likes: 52
From: Florida
AC help please
My AC comp. won't engage normally. I tested the power to the relay on my 76 and it's 12v but the tan wire going to the thermal limiter switch is only 0.9mv when the AC is turned on. I switched out relay with a spare and no change. Is the problem in the ac controls at the console?
I also tested the wire at the comp. and it's 0.43mv. The clutch will engage with direct 12v and I heard it engage once while moving selector through the settings, but only once. What would be the cause of the weak voltage?
any good advice appreciated
Jim
I also tested the wire at the comp. and it's 0.43mv. The clutch will engage with direct 12v and I heard it engage once while moving selector through the settings, but only once. What would be the cause of the weak voltage?
any good advice appreciated
Jim
Melting Slicks
Joined: May 2002
Posts: 2,716
Likes: 121
From: Sulphur LA
St. Jude Donor '05-'06,'11,'13-'14,'16,'18,'19,'24, '25
Were is the thermal limiter switch? I am not sure what system you have in your 76. Power should come from the switch in the dash to the thermistat at the evaporator inlett and than to a high pressure switch and than to the compressor this is how my 77 is. If you could take some pics of your system and post them it would help out alot.
Neal
Neal
Thread Starter
Melting Slicks
Joined: May 2002
Posts: 2,431
Likes: 52
From: Florida
I'm calling the 2 wire switch located on the high pressure line located mid passenger fender about even with filler neck on radiator overflow.
Relay is mounted on fire wall above evaporator box.
I may be calling the switch by wrong name...pressure switch maybe, I think it senses low freon levels and keeps compressor from running.
I have no pictures at this time.
Relay is mounted on fire wall above evaporator box.
I may be calling the switch by wrong name...pressure switch maybe, I think it senses low freon levels and keeps compressor from running.
I have no pictures at this time.
Melting Slicks
Joined: May 2002
Posts: 2,716
Likes: 121
From: Sulphur LA
St. Jude Donor '05-'06,'11,'13-'14,'16,'18,'19,'24, '25
The switch above the evap box is a fan speed switch, it does not effect the comp. The switch on the pass side fender is a high pressure switch to protect the comp. it is inline with the comp and it will need to have 12 volts before the comp will engage. Their is a thermistat at the evap inlett this switch should be the first switch to see power then it should go to the high pressure switch and on to the comp. check the ground at the comp to.
Neal
Neal
Thread Starter
Melting Slicks
Joined: May 2002
Posts: 2,431
Likes: 52
From: Florida
Thanks guys
Last nigt I was messing with the climate controls and it started working temporarilly. The engine was off, I was just listening for the comp. clutch to click and the fan to come on. Makes me think it's the climate controls. I believe the AC changed around 76-77 and mine does have the smaller radial compressor.
On the climate controls, the fan blower does not come on in any AC position.
Last nigt I was messing with the climate controls and it started working temporarilly. The engine was off, I was just listening for the comp. clutch to click and the fan to come on. Makes me think it's the climate controls. I believe the AC changed around 76-77 and mine does have the smaller radial compressor.
On the climate controls, the fan blower does not come on in any AC position.
Tech Contributor
Joined: Aug 1999
Posts: 15,114
Likes: 3,909
From: Connecticut, USA
Jim,
I don't have a schematic for the 76 but I have a couple of the earlier ones if you need me to take look?
BTW I bought the color coded ones that Don Olson over on C1 was selling last year. These are really nice you should see if you can get one, they're worth it.
Gary
I don't have a schematic for the 76 but I have a couple of the earlier ones if you need me to take look?
BTW I bought the color coded ones that Don Olson over on C1 was selling last year. These are really nice you should see if you can get one, they're worth it.
Gary
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Instructor
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You said you heard the clutch engage briefly when going through the controls - I think that if you are low, but not out, of freon in the system, the detection switch will allow the compressor to come on and immediately shut it off when it detects the low pressure. If you've already replaced the switch then I would have the system checked. They tend to leak if you don't use them at least once a month even in the winter time to circulate the lubricant in the freon.
