A/C

ML500

MEMBER
2002 MERCEDES BENZ ML500
5.0L
V8
AWD
AUTOMATIC
140,000 MILES

A/C was not blowing cold. Put in two cans of 134. Now it will not cool at all and the compressor and auxiliary fan runs all the time whether the system is turned on or off.
I expected to see the compressor not turning with the system turned on, but it starts turning the moment the engine is started from cold startup. The auxiliary cooling fan normally only ran when the engine temperature was above 100c, but now it also runs constantly.

1 Reply

STEVE W.

MECHANIC
12,970 POSTS

Put a set of actual gauges on it and check your system pressures. If it was empty it is probably still low. Mercedes Benz AC systems can be a real pain to work on because of all the extra sensors and controls. The pressures need to be correct or the system will act real strange.