C3 Compressor runs all the time

Reply Subscribe

Thread Tools

Search this Thread

May 10, 2015 | 04:38 PM

Burky454

Thread Starter

6th Gear

Joined: May 2015

Posts: 6

Likes: 0

C3 Compressor runs all the time

My compressor runs constantly if the control is in the off position or any of the a/c positions. If I place it on heat it will turn off the power to the compressor. Could it be the sending unit on the side of the heater box? This is where the wire comes from that goes to the compressor. If I unplug from the sending unit the compressor looses power, which makes since. Is that sending unit supposed to be closed all the time? I don't believe the compressor should be running when the control is in the off position. Any help, please.

May 10, 2015 | 05:09 PM

zwede

Race Director

Joined: Sep 1999

Posts: 11,361

Likes: 383

From: Plano TX

Year of the car would be helpful. The AC system changed drastically during the C3 run.

Your problem sounds like a fault in the control head (the part with the *****/wheels on the console).

May 10, 2015 | 05:21 PM

Burky454

Thread Starter

6th Gear

Joined: May 2015

Posts: 6

Likes: 0

Quote:

Originally Posted by zwede

Year of the car would be helpful. The AC system changed drastically during the C3 run.

Your problem sounds like a fault in the control head (the part with the *****/wheels on the console).

It is a 1971 454 automatic

May 10, 2015 | 07:04 PM

ajrothm

Le Mans Master

Joined: May 2006

Posts: 9,993

Likes: 1,136

From: League City Tx

A factory early 70s system with the A6 compressor does not cycle off. It runs continuously, freon regulation thru the POA valve is what keeps the evaporator from freezing.

May 10, 2015 | 08:12 PM

zwede

Race Director

Joined: Sep 1999

Posts: 11,361

Likes: 383

From: Plano TX

Ok, '71 makes it a TXV system that, as ajrothm states, runs continuously. It should turn off if you put the selector in "off" though. There are two micro switches on the side of the control head that regulate power to the AC clutch. The problem is probably in one of those switches. From what I remember one of the switches is specifically for turning off everything when in 'off' (including the blower motor).

The AC should also be off when set to 'vent', and come on in 'bi-level'. If it comes on at the wrong setting, there are adjustments you can make to the switches.

May 10, 2015 | 10:24 PM

ajrothm

Le Mans Master

Joined: May 2006

Posts: 9,993

Likes: 1,136

From: League City Tx

Yeah the compressor should only run when the fan switch is on the first click from the left, thumb wheel in Max, Norm, Bi Level and I think defrost. On HTR or VENT the compressor should be off.

Either your fan switch is shorted, relay is hung up or power to the compressor is staying hot for some other reason.

Shouldn't take much trouble shooting to figure it out.

May 11, 2015 | 08:27 AM

Burky454

Thread Starter

6th Gear

Joined: May 2015

Posts: 6

Likes: 0

Good information, thanks. I will look asset the switches.

May 11, 2015 | 09:04 PM

Burky454

Thread Starter

6th Gear

Joined: May 2015

Posts: 6

Likes: 0

Quote:

Originally Posted by Burky454

Good information, thanks. I will look asset the switches.

I had a loose micro switch on the control. After adjusting and tightening everything works just like it should. Thanks so much. You guys save people like me a lot of heart ache.