68 Mustang AC problems

My dad's 68 mustang's ac compressor stays on no matter where you set the temperature or the vent setting. Like, if the heater is set to on, it still cycles. Does anyone have a wiring schematic or an answer to this?

Thanks, Brian

 

Have you tried replacing the relay? Sounds like it might stuck open.

 

Mark, where would that be located at? And thanks for the reply!

Brian

 

As the owner of a 1967 Mustang with factory air I may be of some help. The '67 and '68 were almost identical in styling and manufacturing.

Does the A/C clutch stay energized or is it just rusted on.
Pull the connector at the A/C clutch and read the voltage with a multi-meter when the car is running with A/C on and take another reading with the A/C off.

Someone correct me if I'm wrong but I don't think these cars used a relay for the A/C.
I'll have to check that out.

You never know with a 40 year old car, a previous owner may have deliberatley wired the the circuit always HOT so it never shut off for some unknown reason.

You may want to go diving under the dash with flashlight and pear around the A/C controls and such for wireing modifications.

My dash is pulled at the moment and all wireing is exposed for a total restoration.......so I'll check mine for some kind of relay.

I do not have a wiring diagram but you may want to check out "Mustangs Unlimited" and go on to their forum and ask the same questions.

 

Thanks Mackey! This is a new system. I have ordered a wiring book for it, maybe that will shed some light on the problem.

Thanks again, Brian

 

If it's a new system, there should be a relay, and it's usually located in the main fuse box under the hood, but seeing this car is a classic, I'm not entirely sure.

I've looked at some schematics, and it looks like the air os all controlled through the EEC computer, but since it's after market, not sure if it truely is in your case.