Vintage Cars: W123 300D A/C problems, vacuum leaks, vacuum leak

Question
Hi Ron,

The car is '79 300D W123, the problem is that A/C is not operating properly due to the hot air blown all the time (despite A/C ON it blows hot air), even if the heater is switched of. I'am suspecting the heater valve with two levers on the fire wall but I am not sure. Have you came through similar problems before? I would like some expert advise before I madly start changing all the parts.

Best Regards,
Jacek

Answer
I hate to be the bearer of bad news but it sounds like your climate control servo.  The gizmo on the firewall, these are prone to breaking down. Is your leaking? they are not easy to repair, and most of the time they are bypassed or replaced.

However before we get depressed , is your AC compressor kicking on , can you see the clutch engage?  If so are the lines cold, if not is your coolant ( freon)  low. When you move the levers in the car, do you hear flaps open and close.  Are you sure there are no vacuum leaks?  ALl must be looked at and ruled out to accurately diagnose issue

Could be a simple vacuum leak, look for broken or loose vacuum lines