Air Con blows hot on drivers side

kheath74

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I have a suspicion that I have a temp fault in my air con in my W220, when I set the air con to 22C the centre console will blow cool air on a day outside at 10C, the passenger air vent when open blows very slightly. The drivers air vent however blows nearly full with hot air, if I close the vent it blows to my feet.

The result is I cant have the air con as it just heats the car as if I had a hair dryer on my feet, I have just had the air con regassed and a overview my a mechanic I trust and he said the general condition of the car was good.

The "Coolant Warning" error was displayed recently once and I am wondering now what the running temp should be for the car, I run at about 90C most of the time after an hour of driving.

I think I will take the car to MB now to look at this air con issue as I can only think that a sensor on the drivers side thinks the car is cold and therefore tries to heat that climate control side.
 

PJayUK

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My W220 runs at about 90 pretty much all of the time (once warmed up) The Aircon however definitely affects the running temperature though. If I turn the Aircon off ie. switch on economy mode, the engine temperature heads up towards 100. Not sure why. I have also had times when the Aircon blows hot air even when its set to the coldest level. It seems to rectify itself after a while and decided to blow cold air again.

Rather odd
 
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K

kheath74

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Malcolm,

I am due to have the brake disks replaced soon, will this be a simple issue for a mechanic to check at that time or is this something that can be done by myself?

I think I can live without air con for a while but it does geta bit steamed up sometimes!
 

television

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It would help if the mechanic new how they worked, we do have a post in the DIY section, take a read of it and see how you feel about it
 

PJayUK

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Malcolm

Would you have any idea why the engine temperature on my W220 creeps up when I turn the Aircon compressor off? (via selecting Economy mode or by turning it off altogether).

On previous car I have owned the reverse was true, ie. running with the Aircon off often caused the temp to drop a little.

Any ideas?
 

bil

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hi,
new to the forum. my W208 seems to have the exact problem with the a/c at the same time my outside temp reading will be jumping from -38 to +58 and any reading inbetween (eg. +2 or +4 when its really +20 outside).
a/c blows hot air when it reads -38, but even the wrong reading (above eg.) a/c is fine. what seems to be the cause/solution. there was a old thread(locked) i searched for dated 2004 and the member's clk had the exact -38 reading all the time.

can anybody have a word of advice.

thanks
bil
 

Tju

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Malcolm

Would you have any idea why the engine temperature on my W220 creeps up when I turn the Aircon compressor off? (via selecting Economy mode or by turning it off altogether).

On previous car I have owned the reverse was true, ie. running with the Aircon off often caused the temp to drop a little.

Any ideas?

I had this happen to me on an E60 AMG W124 and I was told by my Mercedes Mechanic that when the Air Con is on, so are the two electric fans which are positioned on the front side of the radiator, therefore cooling the cooling system, when the Air Con is turned off, these fans are also turned off, I think they only come on automatically when the thermostat detects that the engine is running hot, or over a specified temperature, so Air Con on, electric fans on, Air Con off, electric fans off,

Hope this helps,

Regards,

Terry.
 

bil

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after searching and reading almost every possible forum threads in the US and UK about "hot air blowing from the A/C" i've came to the conclusion that it's the duovalve and was so sure that before i dropped it off i told the mechanic that it's the duovalve and only that . i told him if i had the tools i'd fix myself. so since i pointed out the cause of the problem it should be quite easy to do (like a smart a$$ know it all). i thought i've read enough material that i kind-of know what i'm talking about. the DIY section in this forum has a very detailed thread on how to deal with the duovavle.

so 1 hr later i pick up my ride and he tells me it's not the duovalve and it something simple. i just bought the car used and the last owner had the A/C charged(re-gassed) and filled, and that it was over charged causing too much pressure. that's as much as i understood coming from a layman.

so A/C is fine...for now, but the outside temp display is still stuck at -38.

hope the cool air stays cos someone said MB are known for A/C probs and to replace it with a new one will cost an arm and a leg...maybe even a kidney.

jap car's A/C can give you frostbit problem free, why cant german engineering do the same?
 

television

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Bil the outside temp fault will be the sender under the front bumper, and easy to change
 

bil

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i spoke too soon. a/c is better than before but not the way a proper functioning a/c unit should be. will be paying the mechanic another visit.
"duovalvedouvalvedouvalvedouvalvedouvalvedouvalvedouvalvedouvalve"

malcolm thanks for the outside temp sensor reminder. i think i can handle that once i get the new part, i hear it's really quite simple - plug n play.
 

ventech

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AIRCON BLOWING HOT FROM SIDE VENTS

There is a duo-valve near the fuse box. Like any tap or vale the seals leak when it is old. To prove it cut a couple of strips of aluminium and drill holes in, so that you can fit either side of the pipe entering the duo valve & tighten the bolts to shut off the water flow.

You should then find the side vents are blowing cold air if everything else is OK. You can then either leave in place till winter if youre mean or poor, or buy a new duovalve which is quite expensive in the range £150 to £200.

No point getting a second hand one as it is a wearing item. It is quite easy to fit
 


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