Air con blowing hot

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slug69

New Member
Joined
Apr 23, 2015
Messages
6
Car
C180 Kompressor Coupe
Hi,
I have a 2004 c180 coupe. The problem I have is the air con will only blow hot (28oC) regardless. It has the non digital dual zone via 2 temp dials.
I took it to a garage and the re gassed it. They said the system was empty, they checked it for leaks and said there were none. But this didn't stop the problem.
I have tried the reset by holding the defrost and re circulate buttons, same result.
I have done the paper test on the vent on the air con panel and the sensor fan is working. Is there 2 sensors in the cabin?
If there are 2, is the other in the roof light panel?

Please help, sweaty and Merc's just don't go:eek:
 
If you can hear clicking noises when ignition is on it's more likely the heater flaps are stuck probably due to worn cogs in the mechanism.
 
Get the duo valve checked,they are known to cause the problem
you describe,or search duo valve on here for DIY remedies.
 
Thank you for the advise.
I've not noticed a clicking noise, but I'll listen closely in the morning.
If this is the cause is it something easily fixed?

I ask about the 2nd sensor as the only info I could find mentioned about 1 in the roof light panel. The is a grill on the panel but if there is a sensor present it is failing the paper test.
 
Get the duo valve checked,they are known to cause the problem
you describe,or search duo valve on here for DIY remedies.
I've tried searching for the duo valve as you suggested, but due to my major lack of knowledge of all the different models and the codes for them I am getting very confused!
Apologies for my ignorance, 1st time on a forum and my 1st Mercedes, but what do I need to put in the search box?
 
You could try this
203

To reset heater flaps and actuators

Switch on ignition.

Press recirculated air and defrost buttons on control panel together for longer than 5 seconds.

The LED's in the defrost and recirculated air buttons flash alternately.

Wait until the LED's stop flashing (approx 30 sec) system set to defrost LED on.

Switch off ignition.

After 40 sec re start engine

You have a W203...search around "W203 heater stuck on hot" and some variationss of.
 
W203s don't have a duo-valve - everything is controlled via the flaps.
 
Thanks for the info cws196.
After 1/2 hour searching I thought I was going blind!
 
I've tried the flaps reset and that hasn't unfortunately cured the problem.

Can anyone please advise, is there 2 internal cabin sensors?

The one in the dash panel seems to be working but if there is one in the roof lighting panel I don't think it is working as the paper test failed on it.

If there are 2 the problem may be caused by only one working.
 

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