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Discussion Starter #1
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
:crybaby2:
 

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2007 E320 Bluetec, 2008 320ML CDI
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Feroze,

First of all - nice looking car!

The warm air on the drivers side often indicates low A/C refrigerant.

There is a useful test you can perform that will aid in diagnosis.

On your climate control console, press and hold the REST button until the display changes to a 1 on the left and another number on the right (10 seconds or so). This places the HVAC system into a diagnotic mode.
Pressing the left side Auto button will change the left side channel 1,2,3,..etc. Run through the channels and record the right side numbers and post them here.

When you run the test make sure the engine has been running for 5 minutes or so and keep it running during the test. When you are done press the REST button to restore the usual display or turn the car off.

Here's what the different channels represent and sample numbers:
1 (Inside Temp): 82
2 (Outside Temp): 76
3 (Left Heater Core Temp): 82 and later 114
4 (Right Heater Core Temp): 84 and later 107
5 (Evaporator Temp): 80
6 (Engine Coolant Temp): 186
7 (Refrigerant Pressure): 04
8 (Refrigerant Temp): 91
9 (irrelevant)
10 (Blower Control Voltage) 6.0V
11 (Emission Sensor) 2.4V
12 Sun Sensor: 4.1V
20 Control Current for Auxiliary Fan: 3.2mA (Is this value too low?)
21 Engine Speed: 44 or 4,400rpm
22 Vehicle Speed: 0 (makes sense to me)
23 Terminal 58d: 32 or 32%
24 Battery Voltage: 13.3V
40 Software Status: 164
41 Hardware Status: 85
42 ???: 40
43 ???: 136

Skippy
 

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2001 S210 320 CDI Avantgarde Estate
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If one side is ice cold and one side is warm, most likely is a sticky duovalve. Enter diagnose mode and post values. Just a tip, if one side sticks open and warm air blows one side, press front windscreen defrost for 5-10 seconds and release after. This might help to move plunger inside duovalve all the way and then to return to normal.
 

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Discussion Starter #4
Thanks Skippy,
I will do the diagnosis test hopefully today and will post the results here after the test is done. I shall also perform the test what Tomjones1 wrote.

I don't understand why would the Air-conditioner system would loose Freon, I though that it is a sealed Refrigerant System. Is there a leak at such low miles?

Feroze


Feroze,

First of all - nice looking car!

The warm air on the drivers side often indicates low A/C refrigerant.

There is a useful test you can perform that will aid in diagnosis.

On your climate control console, press and hold the REST button until the display changes to a 1 on the left and another number on the right (10 seconds or so). This places the HVAC system into a diagnotic mode.
Pressing the left side Auto button will change the left side channel 1,2,3,..etc. Run through the channels and record the right side numbers and post them here.

When you run the test make sure the engine has been running for 5 minutes or so and keep it running during the test. When you are done press the REST button to restore the usual display or turn the car off.

Here's what the different channels represent and sample numbers:
1 (Inside Temp): 82
2 (Outside Temp): 76
3 (Left Heater Core Temp): 82 and later 114
4 (Right Heater Core Temp): 84 and later 107
5 (Evaporator Temp): 80
6 (Engine Coolant Temp): 186
7 (Refrigerant Pressure): 04
8 (Refrigerant Temp): 91
9 (irrelevant)
10 (Blower Control Voltage) 6.0V
11 (Emission Sensor) 2.4V
12 Sun Sensor: 4.1V
20 Control Current for Auxiliary Fan: 3.2mA (Is this value too low?)
21 Engine Speed: 44 or 4,400rpm
22 Vehicle Speed: 0 (makes sense to me)
23 Terminal 58d: 32 or 32%
24 Battery Voltage: 13.3V
40 Software Status: 164
41 Hardware Status: 85
42 ???: 40
43 ???: 136

Skippy
 

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Discussion Starter #5
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
 

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Discussion Starter #6
September 8, 2012 @ 9:25 am

Hi tomjones1

I did press front windscreen defrost for 5-10 and released it and did it for 4 times and it is same, warm air from driver's side vents and cold air from passenger side vents . If the car has not ran for may be approximately 8 to 12 months, and the A/C has not been turned on , will it do it?

I have a 2006 E350 and that has 3840 miles and I have no problems with A/C and I hardly drive
 

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Discussion Starter #7
Hi tomjones1,

Here are the test results:

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
 

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'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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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.
 

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2007 E320 Bluetec, 2008 320ML CDI
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I agree with MBGraham.
The duo-valves may require cleaning as well (channels 3 & 4). FWIW, with a similar outside temp my 3 & 4 report 48 degrees.
Skippy


Sent from phone.
 

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Discussion Starter #10
Hi Skippy,

In regards to cleaning the duo-valve, is this something I can do it or I have to go to the dealer? If I could do it myself, can you please explain me in details about the process. Once again, thank you very much for writing me the process about how to do the diagnosos test.
 

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2001 S210 320 CDI Avantgarde Estate
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There is no significant difference left-right so unlikely to be related with a sticky plunger. So leave duovalve for now.
Looks like you are low on refrigerant and actually both sides are blowing luke-warm air.
For proper function of air conditioning evaporator temp should be at 37 degrees F.
Evac, vacuum test and fill to specs if no leak.
 

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Discussion Starter #12
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?
 

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'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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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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1999 E55, 2001 E320, 1990 560 SEC, 2004 ML350, 2001 ML55, 1995 S500, 1998 SL500, 2010 E550 Sport zoo
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The duo valve issue is way over blown on this forum - the most common issue is a proper evac/test/refill which can be done at ANY general auto shop that has the computerized air con evac/fill machine and dealer price for the service is WAY excessive - my area general evac/fill is like $70-$80, and dealers charge north of $200 for same basic air con service.

They evac the system - hold at vacuum for leak test - if all holds at vacuum they refill with 100% fresh R134 by measured weight. zThe machine does the work after they hook up low and high side hoses - it's slick !

All to the good !
 

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Discussion Starter #16
2002 MB E320 with 10,755 miles A/C blows warm air

September 9, 2012

Hi fabbrisd1,

You are correct because I called the MB Dealer and I did mention to him about "Due valve" and he ruled out and said that it is impossible for the due valve to get stuck at this low mileage and the coolant in the system is Factory Coolant. The dealer recommended me to flush out the old Freon, installed the new Freon and then do the dye test. He said that usually the rubber bushing goes bad when the automobile sits for extended months and the system do looses the Freon.

Her gave me a price of $275. I think I plan to take it to a private auto repair place that works on Mercedes Benz and have them check it out. Unless I get a thread from a MD technician who knows the problem

**************************************************************

The duo valve issue is way over blown on this forum - the most common issue is a proper evac/test/refill which can be done at ANY general auto shop that has the computerized air con evac/fill machine and dealer price for the service is WAY excessive - my area general evac/fill is like $70-$80, and dealers charge north of $200 for same basic air con service.

They evac the system - hold at vacuum for leak test - if all holds at vacuum they refill with 100% fresh R134 by measured weight. zThe machine does the work after they hook up low and high side hoses - it's slick !

All to the good !
 

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Please understand that any competant shop that has the "machine" can do the job - there are two hose hook ups - your front hook up is inder a small panel to the right of the radiator - the other is easily found top side.

They code in the machine to the make/year/model - then the machine does the the work.

Dye is NOT needed unless the evac test shows a leak. A dye test, if needed will be like another $40 - I would say 95% of the evac's will be 100% OK - only 5% will have any major leak - which owner's report as a sudden failure of the system since a major leak all the refrigerant blows out fast.

R134 is a smaller molecule than the "old" R12 used in earlier series - so over time it is expected to leak out thru gaskets and such - remember we have 10-13 yr old cars !

I would check your local hard copy Yellow Pages - and many of the "jiffy" oil/auto work pieces have the machine - what the machine extracts goes into one storage cylinder which when full gets sent back to the supplier for proper recycling - what gets filled is all 100% clean R134.
 

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tomjones1,

My comment on the duo-valve was less about the imbalance and more to the 50 degree difference from my experience. His reading is 98 and mine is 48 for similar outdoor temperatures.

The dealers comment that it's impossible for a low mileage car with 10 year old coolant to have a sticking duo-valve is curious. Perhaps that dealer also subscribes to the 'forever' nature of the transmission fluid.

Skippy
 

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Initially thread was about one side cold, one side warm. Sensor readings show both sides warm with insufficient cooling in evaporator. Things are quite clear, the man needs a refill.
 
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