New HVAC blower motor issues, what to try next?
02-15-2022, 10:04 PM
#1
Newbie
Thread Starter
New HVAC blower motor issues, what to try next?
Hello all,
I’m hoping I’m just missing something simple here and someone has the experience to point me in the right direction. My ‘05 E55 HVAC blower motor started to make noise so I replaced it with a new Behr unit from FCP. The motor worked fine for a few weeks, nice and quiet, but then it suddenly stopped working. I took it out and beach tested it with 12v and the fan spun just fine.I tested the fan operation via the control panel a few times as I was putting it all back together. It worked fine. The next day when I drove the car, the fan stopped working again. After reading some posts and doing some digging, I see that the fan resistor/final stage unit is a common failure part. I ordered a Beck Arnley unit from Rock Auto and poped it in there. That has not fixed the issue. I have confirmed 12v at the resistor (large brown and red with blue wires). Here’s the strange part, when I turn on the HVAC, the fan will spin slowly for 5 seconds and then stop. If I turn of the HVAC, pull out the key, wait for a few minutes, it does the same thing. So, I call FCP and ask if they’ve had any bad fans or heard of my issue. They say it sounds like the HVAC control unit is faulty. I ordered a good used HVAC control unit and replaced it…..same issue. I’ve thrown every part that I can at this issues. I know the fan spins, it will do it for 5 seconds when in the car, or when bench tested. Neither resistor, old or new, makes difference, and the control seems to working (not likely I have two bad control units). What am I missing here, what have I not checked? It’s going to get cold again soon here in the mid west and I could really use a working HVAC fan. Thanks for any help you all can provide!
I’m hoping I’m just missing something simple here and someone has the experience to point me in the right direction. My ‘05 E55 HVAC blower motor started to make noise so I replaced it with a new Behr unit from FCP. The motor worked fine for a few weeks, nice and quiet, but then it suddenly stopped working. I took it out and beach tested it with 12v and the fan spun just fine.I tested the fan operation via the control panel a few times as I was putting it all back together. It worked fine. The next day when I drove the car, the fan stopped working again. After reading some posts and doing some digging, I see that the fan resistor/final stage unit is a common failure part. I ordered a Beck Arnley unit from Rock Auto and poped it in there. That has not fixed the issue. I have confirmed 12v at the resistor (large brown and red with blue wires). Here’s the strange part, when I turn on the HVAC, the fan will spin slowly for 5 seconds and then stop. If I turn of the HVAC, pull out the key, wait for a few minutes, it does the same thing. So, I call FCP and ask if they’ve had any bad fans or heard of my issue. They say it sounds like the HVAC control unit is faulty. I ordered a good used HVAC control unit and replaced it…..same issue. I’ve thrown every part that I can at this issues. I know the fan spins, it will do it for 5 seconds when in the car, or when bench tested. Neither resistor, old or new, makes difference, and the control seems to working (not likely I have two bad control units). What am I missing here, what have I not checked? It’s going to get cold again soon here in the mid west and I could really use a working HVAC fan. Thanks for any help you all can provide!
11-15-2022, 07:20 AM
#3
MBWorld Fanatic!
Did you also replace the voltage regulator while you were in there? Both the blower motor and voltage regulator should be replaced in pairs.
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