Climate Control Unit test!
Thread Starter
Newbie
Joined: Aug 2013
Posts: 4
Likes: 0
From: Worcester, MA
2002 C 230K Sport Coupe
Climate Control Unit test!
I have seen so many posts in so many places asking how to test if the control unit is still good on the W203. I havent seen any answers other than "Just replace it and if the blower still doesnt work go after the regulator.
Mine worked intermittently so I got another from Ebay.
Now this one is junk.
The test is to disconnect the plug at the blower motor.
Find the terminal that the blue wire with the red stripe goes into.
Get out your digital multimeter, set it to a low DC range (0-20V)
Set your AAC fan switch to its lowest setting on manual mode (key on).
Ground out the black lead on the multimeter and use the red to contact the terminal for the blue/red wire.
Voltage should be no more than 0.5-0.7 V.
Turn the fan switch up to max and the voltage should be no more than 5.0V.
Above or below, the control unit is junk, provided you have proper voltage going to the control unit.
IF this is all good, then I would go after the regulator and/or blower.
Hope this helps!
Mine worked intermittently so I got another from Ebay.
Now this one is junk.
The test is to disconnect the plug at the blower motor.
Find the terminal that the blue wire with the red stripe goes into.
Get out your digital multimeter, set it to a low DC range (0-20V)
Set your AAC fan switch to its lowest setting on manual mode (key on).
Ground out the black lead on the multimeter and use the red to contact the terminal for the blue/red wire.
Voltage should be no more than 0.5-0.7 V.
Turn the fan switch up to max and the voltage should be no more than 5.0V.
Above or below, the control unit is junk, provided you have proper voltage going to the control unit.
IF this is all good, then I would go after the regulator and/or blower.
Hope this helps!
Newbie
Joined: Feb 2017
Posts: 1
Likes: 0
C class W203 estate
Hi all, I have a 220 CDI C class estate sept 2004 it is using approx. 1.0 litres of oil every 1200 miles of motorway mileage. Is there anything that I should worry about? the car has done 165,000 miles. There are no drips, smells of burning oil or blue smoke from the exhaust. Is this common in a car this age? Or can anyone advise what potentially is the problem. Thanks
Last edited by hikey; Feb 25, 2017 at 04:41 AM. Reason: missed a word
MBWorld Fanatic!
Joined: Dec 2003
Posts: 3,275
Likes: 236
From: BC, Canada
2003 C230K Coupe Orion Blue
Hi all, I have a 220 CDI C class estate sept 2004 it is using approx. 1.0 litres of oil every 1200 miles of motorway mileage. Is there anything that I should worry about? the car has done 165,000 miles. There are no drips, smells of burning oil or blue smoke from the exhaust. Is this common in a car this age? Or can anyone advise what potentially is the problem. Thanks
Please start a new thread the next time you have a question, or tack onto one that's discussing the same topic.
Newbie
Joined: Mar 2007
Posts: 4
Likes: 0
From: Newbury UK
2004 R230 SL500, 2005 W203 C350
I have a 2006 c350 petrol with the 7 speed gearbox, I love the car but I am getting a noxious oily smell when I start the car and drive at low speed through the climate (set on auto).
The oil level in the engine is ok and at speed you don't get the smell only at low town speed. Seems like oil is being picked up by the intake to the climate? Any suggestions on what it could be? There's no oil dripping on the driveway. Thanks for your ideas. Allan
The oil level in the engine is ok and at speed you don't get the smell only at low town speed. Seems like oil is being picked up by the intake to the climate? Any suggestions on what it could be? There's no oil dripping on the driveway. Thanks for your ideas. Allan
Super Member
Joined: Jun 2017
Posts: 899
Likes: 140
2005 E55
I don't think it's the alternator. I have lost my alternator twice and both times you get the battery visit work shop message first. Then while running on only battery once voltage drains down into the mid 10V range you get the stop vehicle warnings. If you got everything popping up at once I would suspect something else.... just guessing from what I saw when I lost my alternator in my experience.
