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AC / Air Conditioner Trouble - Warm at Idle

Old 09-19-2014, 04:52 AM
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2017 GLA 250, 2011 C63 P31 (p30 w/ lsd) (in repair), 2005 C230 Sport Eurocharged, 2003 C320~sold
AC / Air Conditioner Trouble - Warm at Idle

Hi everyone....I have had this problem for some time and looking for some assistance. When I first start my car the AC will only blow warm air.

I was recently low on freon and had the hissing sound so charged it to the high amount to about 45lbs on the gauge--the max green. Before charging it was in the middle of the green range why I put it up at the max. Anyhow this was after driving it for some time and it blew cold while at idle and the pressure on the Climatic Control Diag #7 remained steady.

Next day I start my car and the Diag #7 showed about 30!! Put the gauge on and it showed extremely high. Well figured it worked the night before so would drive it and see what happens. Before my car operating temp warmed up I watched the number fluctuate and drop while I was driving and then rise when I was not moving at idle. It would kick the AC compressor off when it reached 31ish drop the pressure to about 29 then kick back on and cycle like that until I started driving again.

After the car warmed up to normal operating temperature it seemed the reading on the climatic control would not go above 20 and while driving went down to 10.

Is there something that will cause the pressure to rise when the car is not driving? I am not sure if it's directly correlated to the operating temperature of the engine but does seem to be better when the car is warmed up.

There are no errors codes in the SDS. Your help is greatly appreciated!
Old 09-19-2014, 05:19 AM
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2017 GLA 250, 2011 C63 P31 (p30 w/ lsd) (in repair), 2005 C230 Sport Eurocharged, 2003 C320~sold
Here are the readings from my climatic; don't know how to pull any error codes but none in DAS

warm air-
00 84
01 84
02 86
03 75
04 75
05 78
06 201
07 31
08 194

Cold air
00 82
01 82
02 86
03 75
04 75
05 82
06 206
07 11
08 143
Old 09-19-2014, 06:56 AM
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cvx
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W203 C200CDI
Have the same problem with my car too. Blows cold only when driving, but warm when idle. Evaporator core changed, re-filled the system, replaced bunch of stepper motors etc.. nothing

I have a screenshot from Star when its blowing hot but I dont know what the values should be. I might just upload it and translate it to English

Hope you get problem solved, I didnt

Edit: My values

I remember the B12/2 refrigerant pressure & temp values changed when pressing gas pedal hard

Last edited by cvx; 09-19-2014 at 07:21 AM.
Old 09-21-2014, 02:42 AM
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2012 C300 4MATIC Sport
I had this problem 2 weeks ago and i fixed it by changing the compressor after having changed the regulator valve first to no avail.
Old 09-22-2014, 01:06 AM
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2003 C240
Same here a few years back. Compressor replaced no problem since. Get your compressor checked.

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