A/C (C68) Control head?
Thread Starter
Le Mans Master
Joined: Apr 2001
Posts: 7,412
Likes: 259
From: Little Elm TX
A/C (C68) Control head?
Okay. I've been having problems with the operation of this unit lately. It stores no codes and when it's warm out (above 40°) it works properly. If it's colder out, then my defrost won't work because the A/C won't come on. The A/C recurculate switch won't work as well. I'm wondering if anyone has an idea if I might be able to fix the controller; if anyone has had this problem and fixed it without buying a new control head? Possibly the curcuit board? Anything specific to look for?
Safety Car
Joined: Feb 1999
Posts: 3,504
Likes: 4
From: Mexico Beach FL
Re: A/C (C68) Control head? (R94 LT 1)
It stores no codes and when it's warm out (above 40°) it works properly. If it's colder out, then my defrost won't work because the A/C won't come on.
However, this should not affect the defrost controls -- when in defrost, the air should still come out at the base of the windshield.
Thread Starter
Le Mans Master
Joined: Apr 2001
Posts: 7,412
Likes: 259
From: Little Elm TX
Re: A/C (Tom Piper)
It stores no codes and when it's warm out (above 40°) it works properly. If it's colder out, then my defrost won't work because the A/C won't come on.
Both R12 and R134a AC systems are designed with a pressure sensing switch to keep them from activating the compressor when the low-side pressure is below about 45 psi. Since the freon pressure in the system is directly proportional to the temperature, at 45 psi this equates to about 40 degrees F. So, the system is designed to keep the compressor turned off when the temperature is below 40 degrees F.
However, this should not affect the defrost controls -- when in defrost, the air should still come out at the base of the windshield.
Both R12 and R134a AC systems are designed with a pressure sensing switch to keep them from activating the compressor when the low-side pressure is below about 45 psi. Since the freon pressure in the system is directly proportional to the temperature, at 45 psi this equates to about 40 degrees F. So, the system is designed to keep the compressor turned off when the temperature is below 40 degrees F.
However, this should not affect the defrost controls -- when in defrost, the air should still come out at the base of the windshield.
Edit: additionally, if I do click the defrost switch when I'm having this "problem" I don't get any air at all as the fan won't every kick on. Since I know I have the problem, my solution up to this point is to first get in and see if the A/C recr. switch works. If it doesn't, then I don't fit the defrost switch. I just use floor heat and run the fan on 10 so that it fills the car with heat and keeps the windows from fogging up. (and me from freezing)
[Modified by R94 LT 1, 3:47 PM 3/8/2003]
