Mercedes Repair Questions? Ask a Mechanic for Answers ASAP
Hi, it sounds like the compressor or expansion valve may be defective or you simply do not have enough refrigerant in the system. How much refrigerant did you put in the system when you charged it up?
The system holds 2.2 lbs of R134a.
Do you have gauges connected to the system? Can you give me the high and low side pressures?
Can you pull up the actual values on the display when the system is blowing 52 and 75 degrees and post them here? I'd like to see both sets of readings.
Also, do your system pressures stay at 40 and 250 when it is blowing 75 degrees?
I'm wondering if the heater valve is letting some hot water pass through the heater core. I'd like to see the heater core temperatures while this is happening. You could also crimp off the heater hoses and see if it helps.
The evap sensor would usually just turn the compressor off. It would not typically cause the fluctuations. We should monitor all of the actual values while this is occurring. I'd especially look at the left and right side heater core temperatures.
Ok, click here for the procedure for pulling up the actual values on the display. Write them down and post them here and I will review them. I'd like to see two sets of valves. One set with the key on and the engine off and one set with the engine running while the a/c is blowing warm. I just need the values from 1 - 10.
That's good news! I'm glad to hear that it's working.
You just need to click on one of the ratings for my service in order for the website to credit me for my time.
You are welcome to reply back to me here if you need more help with this.
I believe so. I don't have anything to do with the billing end. You would need to contact customer service about that. There should be a link to contact customer service on your screen.