See if any of you could give me a hand with this one, I got a clue myself but I
like to hear it from someone else.
I have a customer with a 1998 W210 E320, who recently Aquired my services after
another Foreign car specialist miss diagnosed a weird high rev engine noise.
The waterpump bearing was gone and caused an unbalanced vibration, the other
shop didn't even missed this but changed the boot that seals the steering
column to the chassis.
Anyway I grabed the fan blade and found 2 inches of play back and forth.
I changed the waterpump last week, problem went away, but the customer called
back complaining about poor heat.
He came back a day later, I found that there was no heat,unless you select "HI"
or "defrost" the heat works fine, so I checked for a unwanted pulse at the mono
valve, sure enough, there is a voltage signal when there shouldn't be one, and
off course you unplug the monovale and heat workes great.
I did at first think that the problem could have been a thermostat that just so
happened to go bad after the waterpump change, so I replaced it before I knew
the monovalve was getting a pulse while heat is aquired.
Question, I think the push button assemply has gone bad, but it is a bit of a
coincidence that this happened right after I changed the waterpump, I mean the
customer said he never did have heat after he picked up his car.
Any other clues, something stupid I'm missing here?.