AC quit working please help 2001 clk55
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Joined: Nov 2013
Posts: 170
Likes: 7
2001 Clk55 AMG
AC quit working please help 2001 clk55
I have owned this car for a year. The Ac has always worked perfectly, but it quit one day at start up and hasn't worked since.
I took the drivers side door panel off to repair the door prop, and decided to refinish the wood trim while I was at it. Car sat for 5 days while I made repairs. I put it back together, window works fine, seat adjustment works fine, etc. but no air cond. when I started the motor. I don't think the door panel caused the problem, but just want everything out there.
I started with searching the web for help and found a bunch of help. First I checked the fuses. Then I pulled the error codes. I had an aux. engine coolant pump error. I replaced the pump and cleared the error code. There are no other error codes that come up, I just get the E FF now when I run the diagnostics.
Here are the readings from climate control,
1-92
2-77
3-170
4-125
5-89
6-192
7-7
8-87
9-2
10-1.5
20-0
21-0
22-0
23-0
24-12.5
40-8
41-5
42-200
43-14
I put a gauge on the low side pressure port and have 120-150 psi. That seems way high for the low side port. The pressure doesn't change motor on or off, compressor engaged or not. I can see the compressor clutch engage and disengage with the EC button. I let the engine temp creep cup towards 100*c and both fans came on for a while and turned off when temp came down. Dash temp gauge seems accurate and stays between 80-90*c when driving.
Any ideas would be appreciated.
I took the drivers side door panel off to repair the door prop, and decided to refinish the wood trim while I was at it. Car sat for 5 days while I made repairs. I put it back together, window works fine, seat adjustment works fine, etc. but no air cond. when I started the motor. I don't think the door panel caused the problem, but just want everything out there.
I started with searching the web for help and found a bunch of help. First I checked the fuses. Then I pulled the error codes. I had an aux. engine coolant pump error. I replaced the pump and cleared the error code. There are no other error codes that come up, I just get the E FF now when I run the diagnostics.
Here are the readings from climate control,
1-92
2-77
3-170
4-125
5-89
6-192
7-7
8-87
9-2
10-1.5
20-0
21-0
22-0
23-0
24-12.5
40-8
41-5
42-200
43-14
I put a gauge on the low side pressure port and have 120-150 psi. That seems way high for the low side port. The pressure doesn't change motor on or off, compressor engaged or not. I can see the compressor clutch engage and disengage with the EC button. I let the engine temp creep cup towards 100*c and both fans came on for a while and turned off when temp came down. Dash temp gauge seems accurate and stays between 80-90*c when driving.
Any ideas would be appreciated.
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Joined: Apr 2005
Posts: 3,784
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From: SCV SoCal
2002 CLK430
Based on the heater core temperatures, the duovalve appears to be open. If you're unfamiliar with the duovalve, look here. I don't know if the temperature at the evap sensor is correct or not, but with 170 degree air coming from the left heater core, it might be.
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Joined: Nov 2013
Posts: 170
Likes: 7
2001 Clk55 AMG
Cleaned the duo valve this morning. Pulled the climate control values after it sat over night.
The thermometer in the garage said 76, and all the temps were within two degrees of that. It seems that the temp sensors are working well. Refrigerant charge dropped to 6. The EC light stays off so that should mean that there is enough charge for it to run. I still have 90 psi on the low pressure side while off and cold, which is normal from what research I have done. It really acts like the compressor isn't running, but I can see the clutch pick up. Still no error codes.
The thermometer in the garage said 76, and all the temps were within two degrees of that. It seems that the temp sensors are working well. Refrigerant charge dropped to 6. The EC light stays off so that should mean that there is enough charge for it to run. I still have 90 psi on the low pressure side while off and cold, which is normal from what research I have done. It really acts like the compressor isn't running, but I can see the clutch pick up. Still no error codes.
Thread Starter
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Joined: Nov 2013
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2001 Clk55 AMG
When cold and off I get 95 psi on both the low and high side. When I turn on the motor and the compressor runs it dropped to about 86 psi on the low side and went up to about 105 psi on the high side. That's no where near enough differential to cool. Is there some part that can cause these symptoms besides the compressor going bad?
Thread Starter
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2001 Clk55 AMG
It looks like they are variable displacement compressors, but use line pressure to adjust the displacement instead of a PWM signal like the newer clutch less designs. So I am starting to think the compressor is stuck on low displacement.
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Thread Starter
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Joined: Nov 2013
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2001 Clk55 AMG
Been playing with the climate control. I know the duo valve is working because I can watch the left and right heater core temps go up and down with the temp controls. When I set temp to low the heater core temps drop to evaporator temp. Unfortunately my evaporator temp is ambient temp. Electric fans kick on at 218* and off at 204*. Low and high side compressor pressure is about 90psi when cold and at rest, it will pull 30 or 40 psi of differential when ac is on and motor is revved to 2500rpm or so. That isn't enough to do much.
I am beginning to suspect the expansion valve. If it is stuck open it may cause symptoms like these.
I am beginning to suspect the expansion valve. If it is stuck open it may cause symptoms like these.
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Senior Member
Joined: Oct 2012
Posts: 335
Likes: 3
From: Lodi, CA
2001 CLK55 AMG
Had the same issue out of the blue, ended up being my receiver / Drier being clogged. $35 and full Vac down of the system, and it fixed the issue completely. 3 "master techs" said it was the compressor, I couldn't accept that at 77k my compressor was shot. These have about 1/4 the size of a receiver drier as the CL55, so they clog easily. I just finally fixed mine yesterday. If you don't pull a full Vac before and after replacing the receiver drier, it won't fix it... Now I'm getting 42 degrees at about 48psi on the low side, silent compressor when it was groaning before. $35 bucks plus 3 cans of 134.
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Joined: Nov 2013
Posts: 170
Likes: 7
2001 Clk55 AMG
After about a month of the ac working good it suddenly lost its charge. I tracked the leak to the rebuilt compressor.
I had suspected a faulty control valve on the compressor as the original problem with my system, but went with a rebuilt compressor to cover my bases.
I decided to test this by installing the new control valve into the old compressor and reinstall it in the car. I was very happy when the old compressor started working normally with the new control valve. It is very easy to change control valves, it is only held in the comp body by a snap ring. Moral of the story is that if your system is having the same issues as mine was changing a relatively inexpensive control valve may be all you need.
I had suspected a faulty control valve on the compressor as the original problem with my system, but went with a rebuilt compressor to cover my bases.
I decided to test this by installing the new control valve into the old compressor and reinstall it in the car. I was very happy when the old compressor started working normally with the new control valve. It is very easy to change control valves, it is only held in the comp body by a snap ring. Moral of the story is that if your system is having the same issues as mine was changing a relatively inexpensive control valve may be all you need.
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Joined: Oct 2012
Posts: 1,427
Likes: 100
From: Florida
2002 CLK 55 AMG cabriolet Eurocharged
A clogged pilot valve in the compressor valve plate assembly was likely the culprit. Rebuilding the compressor or replacement is the only fix.
This happens from contaminants in the system or lack of use. Try to utilize defrost or AC at least once a month.
This happens from contaminants in the system or lack of use. Try to utilize defrost or AC at least once a month.
