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Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53903
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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The AC light won't go off. I tried resetting the codes, but

Customer Question

The AC light won't go off. I tried resetting the codes, but I must be doing something wrong,be cause they are not resetting. # ***** reads 50.7 C, and # ***** reads 13 bar.
JA: Have you seen this code before? Have you tried a hard reset?
Customer: what's a hard reset?
JA: What is the model/year of your Mercedes?
Customer: 2002 S 500
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: I tied instruction from a previous blog
JA: Anything else you think the mechanic should know?
Customer: hello more than likely the a\c system has a fault that has occurred or the freon level in the a\c system is low or out. this is a safety that is built into this system to save the a\c compressor from being damaged. let try this , start the engine, turn on climate system press and hold the REST button for 5 or more seconds. using the d\s left side AUTO knob press or rotate to the right until left side display reads numbers 3,4,5 and 7 tell me what the right side display says, this is in car temperature sensor actual values i need to know esp what numbers 5 and 7 are??? number 7 is the freon level in bars. this 7 number needs to be 9 or higher for a\c system to come on. we can reset this light manually using the in cars a-c pushbutton but if the system has a fault or out of freon , the red light will come right back on. to reset light press and hold REST and double arrow button (recirculation) for 5 or more seconds the screen will change, and codes will appear write down these codes, press or rotate d\s auto button unitl all codes are seen, now press and hold both right and left AUTO buttons at the same time. the codes should erase, now turn off engine and restart engine press ac off button light should go off. let me know how this all works out be glad to help steve
Submitted: 1 year ago.
Category: Mercedes
Expert:  Marty replied 12 months ago.

Hi, sorry for the wait. It sounds like you may not be erasing the codes properly. Click on my video below and see if you re able to erase the codes using the procedure in the video.

Let me know if it works.