PeachParts Mercedes-Benz Forum - View Single Post

dmorrison · #9 07-11-2004, 06:23 PM

Lets back up here a little. Remove the passenger underdash panel. That is where the fan is located. Either remove the fan by unscrewing the 3 bolts or just apply leads to the fan. Lets make sure your brushes inthe fan are OK. AFter removing the fan apply 12 volts to the unit. Be careful it will torque out of your hand if not held tightly. Does the fan operate at full speed. Or does it vary. If it does not operate at full speed then your brushes are bad and need to be replaced. Do a search for that.
this test will eliminate the Ac control and resistors etc.
Get back to us with the results.

Go here for the 123 Manual job 83-120

http://skinnerbox.steaky.org/123_DISK2/program/123-cd-index.html

Then we can test the AC control and or vacuum elements. But with the low flow, varying speeds and noise I'm questioning the brushes and bearings of the fan.

Dave

Just a note. The tempreature control for the AC unit is located just next to the expansion valve. It will try to maintain a proper evaporator temp. If the blower is not blowing air over the evaporator then it will tell the compressor to stop supplying freon. The blower motor adds heat to the evaporator by blowing warm air over it. If the blower is not working the compressro provides a little freon, it cools the evaporator and the temp probe that stciks into the evaporator senses a cold evaporator. Not wanting the freon to cause the evaporator to allow the temp to drop below 35-37 degrees, or it will ice up. It tells the compressor to turn off.
This is why I'm suspect of your blower.
Also If the system was not flushed we may be dealing with a compressor problem. Its whats called "black death"
Look here.

http://www.ackits.com/index.cfm?fuseaction=black%20death

But lets look at the blower first.