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Lou P. master tech
Lou P. master tech, Mercedes Technician
Category: Mercedes
Satisfied Customers: 4054
Experience:  15 years master certified 100% fix rate and have access to factory radio codes, wiring, and instructions.
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Need to find where the AC fan relay is on my ML350 2009,

Customer Question

need to find where the AC fan relay is on my ML350 2009
JA: How many miles are on the car? How old is the battery?
Customer: 105000 don't know how old battery is
JA: Are you fixing your ML350 yourself? What have you tried so far?
Customer: we had the AC system re vac & installed new Freon & leak detector there is no leaks the Ac runs cold all day then all of sudden warm & when it gets warm the far is not running when the fan is running the ac is cold ?
JA: Anything else you want the mechanic to know before I connect you?
Customer: where is the AC fan relay
Submitted: 5 months ago.
Category: Mercedes
Expert:  Lou P. master tech replied 5 months ago.

Hello, my name is***** and i will do my best to assist you.I am going over your story now and will reply back soon with some info,thanks!

Expert:  Lou P. master tech replied 5 months ago.

i will will check the diagram for the relay, i dont think there is one on this model, i know the engine control module controls the fan , what temperature is set on the ac control panel when this happens?

Expert:  Lou P. master tech replied 5 months ago.

ok the fan is the module itself so as long as its getting the proper signals it should work, so either the fan is bad or the ecm is not sending the actuation signal. you need a scan tool to check to see if the module (engine module) is trying to activate the fan or not, or test the red wire with a black stripe to see if there is voltage on it when the fan is not running , fan issues are the hardest to diagnose without a scan tool, they are pretty in depth and they dont fail intermittently, they usually fail and not ever come back on.hope this helps, Please take a second and click the STARS above and rate my service 4 or 5 stars if you feel I have been helpful and please request me in the future. Keep in mind that when you rate it does not end our conversation, you can still return here to me for follow up information if needed, Thanks for choosing just answer. Also , if you feel i deserve one , BONUSES are GREATLY APPRECIATED! Thanks again , Lou P.