A/c freezing!
Thread Starter
Instructor
Joined: Sep 2008
Posts: 111
Likes: 1
From: SE Asia
A/c freezing!
Hi everyone
It seems there are endless issues with the HIVAC system and my car is no different ('87 S4 auto) but any clues to solve the following would be appreciated: The a/c on the car works fine, nice and cold, but the compressor once switched-on then stays on until the evap freezes (basically the compressor does'nt cycle on and off to control cabin temp). I've identified the outside and inside temp sensors and on the evap box there's an anti-ice switch and a thermoswitch, so I'm guessing that any of these may be the culprit but how to check/confirm and have I missed something else?
Thanks for any help.
It seems there are endless issues with the HIVAC system and my car is no different ('87 S4 auto) but any clues to solve the following would be appreciated: The a/c on the car works fine, nice and cold, but the compressor once switched-on then stays on until the evap freezes (basically the compressor does'nt cycle on and off to control cabin temp). I've identified the outside and inside temp sensors and on the evap box there's an anti-ice switch and a thermoswitch, so I'm guessing that any of these may be the culprit but how to check/confirm and have I missed something else?
Thanks for any help.
Rennlist Member
Joined: Jan 2004
Posts: 12,620
Likes: 8
From: Boulder Creek, CA
The freeze switch opens at cold temperature. If it is not opening the contact then the freezing that you describe will occur. If the contacts on that switch are open when your evaporator is frozen, it's the switch. If those contacts are closed when warm and open when cold then it must have been bypassed.
I can see the ad copy now: "AC Blows Ice Cubes!!!"
I can see the ad copy now: "AC Blows Ice Cubes!!!"
Rennlist Member
Joined: Oct 2006
Posts: 1,589
Likes: 47
From: Porterville, Ca.
I had this problem with my '86.5 after a 'reputable' a/c shop went through system (before i started doing the work myself) System would work so well you could not stand it. What I found when I started digging through their work was the freeze switch had been bypassed. Upon removal of controls (to check) and driver side consul panel I found one of those electrical splicers (to provide power for added equipment) on two wires. Using the wire diagrams from the wsm found out it was to freeze switch. Removed splice, ordered new switch from 928intl., installed and system cycled correctly.
Rennlist Member
Joined: Jul 2001
Posts: 6,560
Likes: 113
From: New York
+1 on the freeze switch. Dave, sounds like maybe he needs to know where it is located.
On the firewall, left of center as you face the engine from front is a mounted a box approx 1" x 2.5 ". Opposite end of the wire connections which are on left end of box, it has a long yellow wire that turns into an aluminum probe that extends ithrough the firewall and into the A/C venting. the entire thing is a simple remove and replace.
On the firewall, left of center as you face the engine from front is a mounted a box approx 1" x 2.5 ". Opposite end of the wire connections which are on left end of box, it has a long yellow wire that turns into an aluminum probe that extends ithrough the firewall and into the A/C venting. the entire thing is a simple remove and replace.
