climate control diagnosis?
Member
Joined: Aug 2013
Posts: 153
Likes: 2
From: Bay Area CA
1991 190e 2.3
I replaced the Evap temp sensor and still having issues. I took it to a local a/c shop and they said it's the expansion valve and the drier that I need to replace. Will the compressor not kick in if the expansion valve or the drier is bad?
Senior Member
Joined: Feb 2009
Posts: 317
Likes: 1
From: Germany
C43 AMG 5.5 - 396.4HP
Is your compressor running or not? If yes, please measure and post the Parameters before starting the a/c, after starting a/c and 5 minutes later.
The dryer is exchanged only when the System gets opened, f.e. when you Exchange the condenser or the compressor.
The Expansion valve is a thermical one, there is not much that could be damaged.
The dryer is exchanged only when the System gets opened, f.e. when you Exchange the condenser or the compressor.
The Expansion valve is a thermical one, there is not much that could be damaged.
Member
Joined: Aug 2013
Posts: 153
Likes: 2
From: Bay Area CA
1991 190e 2.3
Thanks popey24. The compressor sometimes work and sometimes doesn't.
In the morning when it is cold, when I turn on the A/C, the compressor will not turn on.
The readings this morning were:
01-68
02-63
03-58
05-60
07-LO
08-68
When the temperature outside went to 80F, the compressor turned on.
I noticed that in the morning when it is cold, the compressor will turn on only when the engine reached its normal temperature and will turn on the auxiliary / condenser fans. The compressor also works when the weather outside is above 75F. Why is that? Am I low on refrigerant? Or is it a bad refrigerant pressure switch?
In the morning when it is cold, when I turn on the A/C, the compressor will not turn on.
The readings this morning were:
01-68
02-63
03-58
05-60
07-LO
08-68
When the temperature outside went to 80F, the compressor turned on.
I noticed that in the morning when it is cold, the compressor will turn on only when the engine reached its normal temperature and will turn on the auxiliary / condenser fans. The compressor also works when the weather outside is above 75F. Why is that? Am I low on refrigerant? Or is it a bad refrigerant pressure switch?
Senior Member
Joined: Feb 2009
Posts: 317
Likes: 1
From: Germany
C43 AMG 5.5 - 396.4HP
Your condensing pressure probe is broken or your System is empty.
With System mot running, the condensing temperature is almost outside temp (08: 68°F=20°C). The corresponding pressure with R134A should be 5.7bar (you need to convert to psi or what you are using), but it is LOW.
Maybe the condensor is damaged, maybe the probe. But Forget that fool that told you your valve is damaged.
Anyway you should Exchange the dryer, because you Need to open the System in both cases. The condensing press probe is lokated on the dryer. behind the Driver side headlight.
I am not shure, if the probe shows LOW or 0.0 when System is empty. I believe there is a threshold below it shows LOW to Show system is empty (leakage). Probably 90% or more it is the condenser.
If you have contrast fluid inside your System, you can detect the leakage with UV light.
With System mot running, the condensing temperature is almost outside temp (08: 68°F=20°C). The corresponding pressure with R134A should be 5.7bar (you need to convert to psi or what you are using), but it is LOW.
Maybe the condensor is damaged, maybe the probe. But Forget that fool that told you your valve is damaged.
Anyway you should Exchange the dryer, because you Need to open the System in both cases. The condensing press probe is lokated on the dryer. behind the Driver side headlight.
I am not shure, if the probe shows LOW or 0.0 when System is empty. I believe there is a threshold below it shows LOW to Show system is empty (leakage). Probably 90% or more it is the condenser.
If you have contrast fluid inside your System, you can detect the leakage with UV light.
Member
Joined: Aug 2013
Posts: 153
Likes: 2
From: Bay Area CA
1991 190e 2.3
The system is not empty. It could be the refrigerant temp sensor or the refrigerant pressure switch. There is refrigerant in the system. Maybe not enough. I will check again. Thanks again and will let you know.
MBWorld Fanatic!
Joined: Mar 2005
Posts: 2,418
Likes: 194
From: America
1999 C43 AMG, 2005 E55 Wagon
The system is most likely not low or empty. Your compressor working intermittently indicates there is pressure present to be intermittently detected and thus making the compressor engage. Still a huge likelihood it's a sensor (pressure, evap temp)
Senior Member
Joined: Feb 2009
Posts: 317
Likes: 1
From: Germany
C43 AMG 5.5 - 396.4HP
For sure that's your Problem: 07-LO
normally press probe broken or leakage.
If it is fine sometimes, maybe you have a contact Problem (corrosion)?
There is an outside temp Limit that blocks cooling, but is is rather low (I think 4°C / 40°F)
normally press probe broken or leakage.
If it is fine sometimes, maybe you have a contact Problem (corrosion)?
There is an outside temp Limit that blocks cooling, but is is rather low (I think 4°C / 40°F)
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Member
Joined: Aug 2013
Posts: 153
Likes: 2
From: Bay Area CA
1991 190e 2.3
Hi popey24. I called my local MB dealer and asked for the pressure switch. They have it in stock so I bought it. I took it to the same place and asked then to recover the freon and replace the pressure switch. He replaced the pressure switch, evacuated the system, and charged with R134a - 1.9lbs. In started the car and turned on the A/C and viola! The A/C worked!!! So it was the pressure switch after all. Thanks for your help.
