Hi, The car is a 1996 E230. I posted last week about a possible duo-valve problem (one side cold, one side hot)

I checked it out and it was not the problem. The hose going to the duo valve was shut-off years ago.

The EC light was now on. I had a refrigerant re-fill and EVERTHING went back to normal. Both sides of the vent are now cold.

After driving with a cold aircon for about 30 mins, the A/C suddenly went back to hot and the blower opens and closes erratically, ruining the engine idling.

I pulled out the codes and came up with this:
232 Refrigerant Pressure Sensor

ACTUAL Values while the engine is ON with the A/C

HEATER CORE 27
EVAP TEMP SENSOR 30
REFRIGERANT PRESSURE jumps from 24 to 36 every 2 seconds
REFRIGERANT TEMPERATURE SENSOR 36


I went to a mechanic and he said the compressor needs replacing.
Or is it the refrigerant temp sensor?
Or both?

Please help.

 

Does your compressor still cut in, and if it does, is it hot enough to burn you if you were to touch it?

 

Yes, the Compressor still cuts in or still turns on. I can determine this since if I push the EC switch off, the engine's idling is a bit higher and lowers if the EC switch is turned on.

 

too high. did you put the right quantity on it? (according to the capacity writtten on the plate on engine bay) maybe +/- 850 grams.

if quantity is correct, it can be the filter drier, expansion valve, or the compressor itself.

check the pressure sensor too because there is a purging valve whenever the pressure goes beyond 24 bar.

 

Ohhh, I brought the car to a non-MB car aircon specialists.

It may be possible he placed too much "freon" 134A. since this happened only on the day he re-filled my refrigerant. That is probably why the "refrigerant Pressure sensor" indicator on the car had an error?? Did he damage this sensor part???

 

most probably not.

better evacuate and vacuum the system and put in the proper quantity and test again.

the refrigirant temp sensor tells that the overpressure wasn't cause by the expansion of freon through heat... which could mean overfilled.

remember that the control unit will cut off the compressor after 20 bar or less than 2 bar to protect the system. at less than 2 bar there will be no more lubrication flowing around but 20 bar is more than the hoses and other circuit design can maintain.

BMW got higher operating pressure at 26 bar. in MB, 14-16 bar is ideal enough.

 

While the system is empty, I would recommend checking the oil for contamination. If there is any grey build up in any of the pipes, Get the whole system completely flushed. Especially the condensor.

 

Thanks guys. I will go back to that A/C shop again to check if it was overfilled. He is used to Japanese cars.

I hope nothing serious is broken......

Thanks. I'll update later.

 

SOLVED IT!!

I went to the A/C repairshop and evacuated the overfilled 134-a gas. I said to just put it in 14-16 bars but he did not believe me. He said 30 is ideal. I insisted to release some 134a gas and true enough, the aircon is now cold.

I checked the on board computer on the A/C switches and it said REFRIGERANT PRESSURE is now 12-13. I think he put out too much 134a since 15 would have been ideal. But At least now, the A/C is cool enough.

I think his gauge is defective since when I left the shop, he said the Refrigerant pressure is at 30 bars.

I also checked the ERROR CODES and the (232) Refrigerant Pressure Sensor is not indicated anymore. Also, Both Left and Right vents are now cold.

Thanks Sleepwalker!! PROBLEM SOLVED....

 

so the other side was actually warm and not hot. K_alavi was right on previous post.

have fun.