A/C pressue switch wired to the compressor?
Thread Starter
Instructor
Joined: Jun 2010
Posts: 130
Likes: 0
From: Summerville SC
A/C pressue switch wired to the compressor?
My recently purchased 81 has been blowing A/C lines because of the way the fans were wired and now I'm trying to rewire my Be Cool fans, adding the A/C relay harness.
Note: My Engine is not stock, and I have a serpentine belt system. The compressor is not stock either.
1. My A/C Pressure switch (near the accumulator) has two green wires (light and dark) and one of them goes directly to the compressor which only has one wire? The other into a harness and into the vehicle. Is this right? The prints seem to show it going to the A/C selector switch, and the other going somewhere else. Why would it have been wired directly to the compressor?
2. I am thinking that exposed compressor wire is the positive side? And the ground is part of the support systemn and not a wire?
3. The terminal on the Be Cool sending unit is bad, what is the best one to replace it with? I see several temperature ranges to choose from. I am leaning toward a 195 Degrees On/175 Degrees Off unit.
-J
Note: My Engine is not stock, and I have a serpentine belt system. The compressor is not stock either.
1. My A/C Pressure switch (near the accumulator) has two green wires (light and dark) and one of them goes directly to the compressor which only has one wire? The other into a harness and into the vehicle. Is this right? The prints seem to show it going to the A/C selector switch, and the other going somewhere else. Why would it have been wired directly to the compressor?
2. I am thinking that exposed compressor wire is the positive side? And the ground is part of the support systemn and not a wire?
3. The terminal on the Be Cool sending unit is bad, what is the best one to replace it with? I see several temperature ranges to choose from. I am leaning toward a 195 Degrees On/175 Degrees Off unit.
-J
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
1, the switch has 2 wires, 1 to the compressor clutch, the other to the switch on the AC control. The comp clutch is grounded internally, so only 1 wire.
2, yes, exactly
3. 195/175 is a pretty good seletion, put it in the passenger head. and delete the stock sender on that side
2, yes, exactly
3. 195/175 is a pretty good seletion, put it in the passenger head. and delete the stock sender on that side
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
Don't know what refrigerant you are using, but if converted to 134, then a high pressure cut off switch should have been installed by law to prevent your hoses from blowing.
The stock system had a pressure cycling switch in the line.
When changing to electric fans for an a/c car, fan must run with a/c on or the head pressures can easily reach critical and lines will blow (without the high press switch)
Best is you will wear compressor prematurely.
The stock system had a pressure cycling switch in the line.
When changing to electric fans for an a/c car, fan must run with a/c on or the head pressures can easily reach critical and lines will blow (without the high press switch)
Best is you will wear compressor prematurely.
Le Mans Master
Joined: Aug 2003
Posts: 7,720
Likes: 12
From: Chattanooga TN
The fan(s) have to run with the a/c on or you will blow lines. If you have a high pressure switch, you can wire it so that the fans turn off at highway speed basically (when there is sufficient airflow to reduce head pressure). That is the way most cars with electric fans are wired.
Drifting
Joined: Jan 2004
Posts: 1,991
Likes: 3
From: Piscataway NJ
The pressure switch near the accumulator is the low pressure switch. A high side pressure switch is usually mounted at the back of the compressor. Both switches would be wired in series with the compressor. The compressor being last in the series would provide your ground.
Thread Starter
Instructor
Joined: Jun 2010
Posts: 130
Likes: 0
From: Summerville SC
Success!
I got it all finished up and filled the system today. Since I do not own a vacuum pump, I took it down and had it filled at my local Firestone shop. Anyway, it seems to be working great.
I never found the high pressure switch. I am thinking it was not added when the system was converted to R134. That may add to the explaination of the ruptured hoses.
Thanks for the advice, 1 project down, 213 to do!
I never found the high pressure switch. I am thinking it was not added when the system was converted to R134. That may add to the explaination of the ruptured hoses.
Thanks for the advice, 1 project down, 213 to do!
