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MB E320 2002 AC Blows warm air from Drivers Side

29785 Views 40 Replies 16 Participants Last post by  tony1963tony
I have a 2002 E320 and it has 10,755 miles on the odometer. I don't drive the car too often. I decided to drive the car today and turned the air-conditioning on and put in on automatic climate control. Just noticed that the air is blowing out cold from the passenger side vents but blowing out warn from Driver’s side vents. I even tried the Manuel mode instead of climate control. Any one knows about this solution or problem. I purchased the car brand new in December 2002 and also purchased a full 8 years extended warranty. But now all the warranties are expired and the vehicle has only 10, 755 miles and still smells and looks like a brand new automobile. The battery is still the original and gives no problem.

Any suggestions why it is blowing warm air from Drivers side vents when the air is on and the temperature set and 65 F


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September 8, 2012 @9:10am

Hi Skippy,

I just finished doing the A/C diagnosis test and here are the results as follows:

1 (Inside Temp): 91
2(Outside Temp): 96
3 (Left Heater Core Temp) 91
4(Right Heater Core Temp) 87
5(Evaporator Temp): 91
6(Engine Coolant Temp): 190 later 191
7(Refrigerant Pressure) 06
8( Refrigerant Temp) 107 later 111
9(irrelevant): 27
10(Blower Control Voltage) 4.5
11(Emission Sensor) 1.7
12(Sun Sensor) 4.3
20(Control Current For Auxiliary Fan: 3.2
21 (Engine Speed): 42
22(Vehicle Speed): 00
23(Terminal): 32
24(Battery Voltage) 13.1
40(Software Status) 164
41(Hardware Status) 91
42(???): 40
43( ???): 136
Your refrigerant is low. Pressure as measured on item 7 should be about 15.

Freon is a very "slippery" fluid and is difficult to contain. It's not uncommon for MBs to develop leaks after 9 or 10 years.

You will need to have shop check out your system. They will likely evacuate it and then recharge with proper amount of R134a along with a dye. After driving for a week or two, they will be able to inspect and determine where the leak is.

I know from experience that it is frustrating to have expensive A/C repairs when the car is little used and A/C seldom needed.

Some owners will try a temporary solution. Walmart sell R134a and recharging kits. It's easy to do and the A/C may work for a while. But not a long term solution.

Good Luck.
After running the engine for 15 minutes and changing the climate control from Auto to Manuel and then switching it to defroster, now both the sides (passenger and driver) warm air is blowing out.

From Skippy’s answer, he also mentions that to check duo-valves, have you any idea where these dup valves are located?
There is a DIY in the stickies on how to clean the Duo valves. But in uour case it is very doubtful that that is the problem. Before taking duovalve apart, try clamping the hose that comeout the front of the valve. That should stop any hot coolant from flowing through the duovalve and affecting the A/C.

But unless you see 15 displayed for item 7, then don't waste time on the duovalve.
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