psaldanha

So i have a strange problem.

I have a w204 C220 CDI 2008 with automatic a/c. The a/c is working fine (its blows cold and hot air as requested). The problem is that there is always hot air (above ambient temperature) blowing to rear passenger from the air exit below front passenger seat. Just that exit. No matter what i set for temperature at front or back control, is always blowing hot air just front that exit.

What could it be?

Thanks!

Moto_Guzzi

Manual mode:I had similar problem after buying my car set aircon cold but get heated from behind. I then figured the rear outlet is producing hot air. I then set it to 18c, but after switchoff its back to hot.
I then figured the aircon system must be set to manual control, then the rear is the same as the drivers front set on cold, or maybe then the rear applicable side follows the setting of the front, dont know if this normal, but this is how myne function up till today.


Is your setting Auto or Manual-?

psaldanha

Thanks for the help!

No, i get hot air just below front passenger seat outlet to the foot´s rear right passenger. Its very strange. It happens in manual or auto mode. Even in mono (one set to everything), i get hot air just in that place.

Tried with A/C on, A/C off, just ventilation. Always the same. I just dont get the hot air if i set the direction just to windshield. Maybe is the valve that is stuck and sends hot air to that specific place.

Any thoughts?
Where is located the valve?

ChazThePhoenix

is your recirculate not working? sounds like its bringing in outside air only

psaldanha

Well, will try to see if the recirculate mode changes the temperature of the outlet mention above. The weird thing of this all is that is just from that and only that outlet mention above that is getting hot air. Way above temperature air from outsite...

psaldanha

So, update.

It can be a faulty duovalve or a faulty interior temperature sensor. Its has one both side. Dont know if it has one at rear. My w204 has a 3 zone climate control (driver, passenger and rear), with a rear temperature and fan control independent.

Borowatz

Any update on this situation?
I have same problem with my W204 C200 2007 model Avantgarde. 3 zone Climate as well, but it's blowing hot (not hotter, really hot air) only below passenger seat.

My diagnostic system says that there is sporadic fault with rear air temperature sensor but i would like to know experience from others what happened so I will be prepared.

ps: coolant liquid should be okay since it was checked 5 months ago

Thanks in advance.

psaldanha

Hi!

Sorry not reply before but was out on holidays!

The problem on my car stays, as i jave done nothing to it. It just annoys me on a long trip, as the air inside get a little hot.

It still gets hot air on rear passeger footwell and rear middle outlet. So i assume that it must be a inside temperature sensor.

In the few days will look out for the rear temperature sensors and will test will a sensor from the front (assuming that is the same connection).

Its a quick and cheap fix if its just the sensor. Or even better if it a bad connection or something.

Talking about AC, if i turn it on, i get good cold air in every outlet except the rear outlets.

So:
will test and try to change rear sensors.
Then will post results.

To help, check the pdf i post here now.

Borowatz

Oh, look at that diagram . Thank you so much.

ps: I just bought a new rear sensor, but I won't be able to replace it for a month at least.
But anyway, if I get some updates will post it here.

Fun fact, couple of days ago my evaporator froze, I noticed it when air wasn't blowing at all and then I saw in engine area that pipes from compressor were frozen... Then 3h later everything was working just fine (except rear right leg blower).