AMER984

I have a 98 w210. The AC blows an ice cold air when starting the car and the engine is idle(the car is not moving). Once either I drive the car or just give it an acceleration through the gas pedal (the car is not moving) the AC gradually starts blowing warm air. If I turn off the AC for a while and run it again the AC blows a cold air again for some time (3-4 mints) or less then blows a warm air again.

I faced this problem when I used to have a leak, and the mechanic found out that the leak is coming from the compressor pressure valve. He replaced it or even solders it I don't remember. But also he changed the filter bottle and as far as i remember he changed the refrigerant temperature sensor which is found above the filter bottle.
Since that time on, there is no leak but i started to have this issue (blowing cold air then warm one).
For the error codes I have performed the test and i got the following:

EB1 227
EB1 231
EB1 232
EB1 234

EB1 235

After clearing those codes, only the EB-234 remains, so I've changed the sun sensor and after the clearing no errors appeared. But the problem is still there.

So I have decided to replace the external temperature sensor with the plug as i had intermittent connection with the plug. The same for the refrigerant pressure and temperature sensors on the filter bottle has been replaced as well. I recharged the system with the 134a but the problem remains.

I have the following note: when the external temperature sensor has been replaced I found out that the temperature showed on the dashboard is the same as on the diagnostic code #2 only the beginning when running the car but after a while, i found a lot of deviation. I mean when the dashboard shows 30 C the diagnostic code could show 39, or 42 which is higher than the actual. So I am wondering if the refrigerant temperature sensor is doing the same. So it could be it is giving high temperature reading to the control unit which makes it not working properly!!!!!!!!!!!

The following are the diagnostic codes just after running the car and the engine is idle(the car is not moving):
1. 30
2. 42
3. 06
4. 07
5. 02
6. 78
7. 13
8. 53
9. 00
10. 1.3
11. 4.3 (after a while it shows E)
12. 3.8
20. 2.0
21. 06
22. 00
23. 00
24. 13.1
40. 71
41. 34
42. 72
43. 152
Then I kept pressing on the gas pedal for a while, and the evaporator temperature on the diagnostic code #5 started to increase gradually and the pressure sensor code #7 started to decrease gradually.
Many Thanks

wally AMG

Replace the heater control valve

AMER984

Thanks Wally,
where is this heater control valve located?? do you mean the emission sensor??
are those a symptoms of an emission sensor failure?? what has the heater to do with the AC??

Plutoe

there is no heater control valve -------1231 is the engine coolant temp sensor that needs changing----the best evap temp is about 41 degrees. Good luck

AMER984

But when i cleared the errors, the 1231 is gone. and for the evaporator sensor, as you see it does give the temperature values correctly.
I think there is some thing fishy!!!!
could be the auxiliary fan is not working properly??? as it never worked on high speed!!!!

Plutoe

No you are learning----first extract the fault codes-----then clear the codes---Then run the car for awhile then extract the codes again----what faults reappear-----those are the suspect for repair. Good Luck

AMER984

ok, i did clear them then after a one day or so. i have read them again the only one is still there is EB1 235 as well as the sensor code # 11.4.5 (after a while it shows E) are those related symptoms to my problem??
By the way, the mechanic is saying that the compressor is defected, is that possible???

Plutoe

In the macro sense all of the sensors provide data to the AC controller to operate at design------that said, the fault 1235 is a emissions sensor fault, the sensor is under hood on the passenger side just behind your control module box---it's thin silver color and its function is to sniff pollutants including refrigerant.

I would unplug and reconnect and do the fault test again----does it show up as faulty. In any event it has no bearing on the cooling issues. In fact NOW with no faults you should not have a problem.

Regarding your mechanic------based on what you have said here---what possibly could lead him to his conclusion---have him explain to you why he believes the compressor is bad and what tests he performed to substantiate his belief.