Well I took my 3 hour ride again and halfway up a/c flaps started problems again.Remained closed and no air coming thru although I could hear fan blowing up a storm. According to this post
http://www.mbnz.org/forums/forums/thread-view.asp?tid=1214147&posts=6
You need both vacuum and pressure to operate flaps.I have written about my SIMILAR problem also in that post. My car,passes all flap tests until I drive over one hour at highway speeds. Then the flaps will not work according to the test flap method. I get no codes either.
I just drove back and same thing happened 1 1/2 hours into return.After flaps closed I pulled over and tested them and they failed all tests.But after 30 mins more flaps opened again. I brought it to ex MB mechanics who says car has vacuum and called an active MB tech who said it could be that the EVAPORATOR TEMP SENSOR freezes over long haul. First they said it might be switchover valve block. It only occurs after more than 1 hour of highway driving.
Do any of you experienced guys, agree with this diagnosis.I remember when evaporator etc was changed I used to get heavy condensation in front and out of center vents on warm humid days. I must decide if I will have them change the sensor tomrw. Its a $65 parts vrs the $2xx part the switchover block was.
Again it never happens in city, only when I go on long rides.
Thoughts please?
PGP[:)]
I had evaporator freezing up on long drives with high humidity. Easy to check: put it in economy mode EC. That will disengage compressor. If the airflow gets back to normal after 5 - 10 minutes, you problem is iced up evaporator.
Mike
Thx for that info. Thats exactly what I did 2 days ago, but neglected to add it to my post. It came back on after 30 mins or so.I did not tell my MB guy that. My benz guys said it was the EVAPORATOR TEMP SENSOR and he changed it today. Cost $30 and drove 2 hours without a problem I do not know if the humidity was less today , but i tried to replicate the circumstances when it occurs and so far so good.
What do you do when yours freezes aside from puttting it in E mode? I will let you know if I take a long ride and it happens again. I drive with sunroof open and a/c on auto at 68 degrees. I saw condensation forming on center vents again today as it has in the past , but that does not always happen when vents close up.
Linear Mode
