I have a 1989 Mercedes Benz 560 SL w/less than 68K miles on it. It’s in mint condition and has obviously been driven very little and garaged its whole life. I’m having an ongoing problem with the AC that my mechanic is seemingly unable to determine the cause of and correct. The a/c sometimes blows cold air, then changes to warm – hot, even – and no amount of fiddling with the panel controls or turning it off and on again seems to correct it. It’s unpredictable at best, no rhyme or reason to if and when. It`s been tested for coolant leaks and none have been found, have also had freon added and it is not leaking. Mechanic things the control panel itself may be out of whack but i think he’s grasping at straws…besides, where am I ever going to find a replacement HVAC front control panel for an '89 MB 560 SL? Help!!
I bet you can find the part, it’s the diagnosis you don’t have. Those HVAC systems do cause problems, but that just means folks figure out how to fix them. You might check on SL forums for another mechanic in your area, and also post your question there. There are lots of these around, folks know how to keep them working well.
p.s.-have all the vacuum lines been gone over?