78 300D A/C blows hot
 

I absolutely despise hvac systems in cars, and hoping this is something I can tackle.. Otherwise if I take it somewhere, I'm sure unessasary parts will be thrown at the car. Anyone in the Charlotte-hickory area that knows these a/c systems in and out? ;)

I've owned this car for a few months, and I'm almost certain when I test drove before purchase I checked to see if the a/c worked and it did.


My heat has been working fine, zero issues. I went to turn the a/c on today, and it was blowing insanely hot air. With my 300d being an early year, I know the climate systems have changed but mine has been updated to some kit. I don't know enough about any of it to even say which kit.....

What should I be checking?




Thanks.

special consideration with yours because it has been converted from the servo style ACC unit to the unwired tools electronic "servo" thing. It's probably a vacuum leak. see that little vacuum controlled pod plumbed into the heater return hose down underneath left side of the AC compressor?

That should be getting vacuum applied to it and holding it closed when you've got the temperature selector wheel in the blue. it is normally open so if it looses vacuum its heat all the time.

use vac tool right there first to verify it works. should feel cool air in the vents.
if that is good then you'll have to go from there and work through the system to find the fault.

I bet its the main vacuum supply for the "servo" unit. little yellow tube around the back of the engine was about the worst of the vacuum hacking that was in there.

The yellow vacuum hose is good and connected.

I will have to find a vac tool to test that unit.

Always something :)


Thanks!