W140, no cold air

[Californian]

The AC on my 1992 300SD (W140) is blowing hard, working very well, but no cold air. How could I determine if this was an Evaporator problem ? Thanks.

Also, could someone tell me if this one uses the old R12 or the newer R134 ? Thanks

When your car won't start, the very first and most basic troubleshooting step is to make sure there is fuel in the tank. The equivalent to that basic first step in a/c diagnosis is to see if there is refrigerant present. The only way I know to do that is by connecting manifold gauges and reading the pressures.

Post the pressures here and we can take it from there.

Good luck,

[Californian]

Thanks Larry. I will do my best to get the pressure reading. Any tips will help though. What do you use to measure the pressure in this case ?

[Californian]

Does anyone know where in the San Francisco Bay Area I can rent the tool to diagnose my AC system ? Thanks.

[sixto]

Originally Posted by Californian

Also, could someone tell me if this one uses the old R12 or the newer R134 ?

I'm pretty sure all W140s were delivered with R134a. There should be a service tag in the engine bay describing the refrigerant.

Originally Posted by Californian

Does anyone know where in the San Francisco Bay Area I can rent the tool to diagnose my AC system ?

You can get R134a gagues at Pep Boys.

Larry, are the any cautions in using gauges? Seems to be something you should know how to use vs a vacuum gauge or timing light.

Sixto
95 S420
87 300SDL

[Californian]

Sixto, Thanks,

I'll be looking at Pepboys soon for the manifold gauges.

[300sdlguy]

Chances are its gonna be the evaporator: Here is a link to a great site this guy is meticulous with his S500 Coupe, and had LOTS of good advice and great pictures to help you along.

http://pages.prodigy.net/jforgione/MB_AAC.html


http://pages.prodigy.net/jforgione/AC_Seal.html


This is the MAIN page for all the other repairs and awesome tips he has for the 140 series.

http://pages.prodigy.net/jforgione/MB_S500.html

[Californian]

Thanks so much Chris.