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Marty
Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53150
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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Marty. How are you?

Customer Question

Hi Marty. How are you?
Submitted: 1 year ago.
Category: Mercedes
Expert:  Marty replied 1 year ago.

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?

Expert:  Marty replied 1 year ago.

The system holds 2.2 lbs of R134a.

Customer: replied 1 year ago.
Hi Marty, I have changed those again, and vaccumed and recharged system with proper freon.
Expert:  Marty replied 1 year ago.

Do you have gauges connected to the system? Can you give me the high and low side pressures?

Customer: replied 1 year ago.
40 on low side. 250 on high side.
Customer: replied 1 year ago.
there were no codes in the self diagnostic through a/c control panel in car.
Expert:  Marty replied 1 year ago.

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.

Expert:  Marty replied 1 year ago.

Also, do your system pressures stay at 40 and 250 when it is blowing 75 degrees?

Customer: replied 1 year ago.
Hi Marty the readings do fluctuate, coming to a stop or slow acceleration is when they mostly happen. Right now i am sitting still in car, temp gauge shows 51.3 degrees. When the take off the temp goes up. Now i am driving and temp is at 62.8 at 40 mph. When I stopped for 5 seconds it went up to 68 degees. Now i took off again up to about 25mph and temp started dropping, now i am at a complete stop again and temp is 53.2 degrees.
Expert:  Marty replied 1 year ago.

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.

Customer: replied 1 year ago.
Will check tomorrow and get back to you. Would the evap temp sensor cause these fluctuations?
Expert:  Marty replied 1 year ago.

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.

Customer: replied 1 year ago.
Hi Marty, thank you for your help, I do appreciate it. I just drove home and it did not fluctuate one time stayed right at 51 to 53....
Expert:  Marty replied 1 year ago.

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.

Customer: replied 1 year ago.
Hi Marty, Good Morning. How are you? The A/C is working great today. Maybe it just took some time to adjust. Have been driving, stopping and going. Not one issue. I am monitoring it with a manual temp gauge. Not a single fluctuation. What do I owe you for your time?
Expert:  Marty replied 1 year ago.

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.

Marty

Customer: replied 1 year ago.
Not sure how this works, it stated that I pay 5 dollars if you do not resolve my requests. I know what uou said is very knowledgable, and how uou dealt with me was very profesional. I would rate you a 10, but if I do that mean I pay the full 28 dollars?
Expert:  Marty replied 1 year ago.

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.

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