Mean Gene 4.2

Here I again with my '87 5KSQ. Had the A.C. all fixed up nice and tight last year. Worked great until one day when the temp inside the car got warmer and warmer and then warmed-out totally (regardless of adjustment to control unit on dash). Shop checked the A.C. connections and compressor and entire system was functioning properly. Odd thing is, it can do the same thing when the heater runs: the temp will get cooler and cooler until there is virtually no heat, again regardless of control unit temp setting (even on econ, i.e. without A.C. compressor). Anyone experience this? Replies appreciated. Signed, My Shop Mechanics In Ohio Are All Baffled.

ottochal

Check the vacuum lines and servos for air ducts
in the dash (center), also the AC/heater control
unit behind the glovebox. Good luck.

Evilclown

I'd start with checking the heater valve itself, it sounds like the diaphragm isn't holding vacuum, and it's slipping to its normal "at rest" position(no load on the diaphragm). Also check for a vacuum leak going to/from it, but it really sounds like the thing isn't holding vacuum.

DaveN

it is behind the glove box.

jimmux

Hi, did you ever get it fixed, I've got a similar problem. would love to hear how you got on...