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need help on blower AC issue. Got in the car today and noticed the AC wasn’t working. After investigating further appear that the fan was not working at all regardless of how I ran through the fan switch either off all the way through the setting of seven there was no air coming out of the vents. Turned it off turned it on no luck got home and try to investigate. Fuse to the blower fan is OK. It would appear when the ignition is in accessory mode to the fan does come onIntermittently but not coming out through the vents. Took the cover down and remove cabin air filters which clearly needed replacing. Then took the blower fan out. At first appeared that perhaps it was burned up as the wires were black but retrospectively now I’m not thinking that is the case. When I plugged it in and just try to run it with the car started the fan was working although it appears to only be operating at a high speed regardless of me trying to change the fan speed through the switch. How do you thoughts or ideas on what it could be couldn’t still be the fan motor even though it’s operating on just one speed? Is there a rheostat that could be affecting the fan speed? Trying to figure out why it wouldn’t be pushing through the vents. I haven’t put it back up yet to see if it would do that as I want to try and diagnose it while I’ve got it out. And before I go to a chiropractor for an adjustment! thanks for any help you can give. Car is 159k right now. I’ve had for 130k of those’
Reading some more and it seems like it’s resistor? Concluding this based on fan staying on one speed all time. Not sure if fan started working Inc ei cleared all crud out of it as it didn’t blow at all before through vents. What are your thoughts?
Well I thought I had it fixed. Replaced resistor/regulator. Tested it out of being fastened back up and all speeds worked on both sides. Thought I had it. Put it all back up and new filters and same issue! No control on fan speeds and no air coming out of vents. Thoughts?
Check it. There might be more than one HVAC relay....Pull the relay out and swap it with another one and see what happens. Sometimes if the relay is bad once it's removed you shake it and if it makes a rattle noise it is definitely bad.
Check it. There might be more than one HVAC relay....Pull the relay out and swap it with another one and see what happens. Sometimes if the relay is bad once it's removed you shake it and if it makes a rattle noise it is definitely bad.
There is no relay controlling this fan. It is control by the regulator.......... which I am guessing you already replaced?? I always have a tendency to replace both the fan and the regulator together. The black stuff that you find is actually coming from the internal wear of the fan motor. I do not know what brand of regulator you installed but keep in mind cheap Chinese regulators do work as they should. The regulator gets a message from the AAC control module on what speed to run the fan at.... So you also need to check that you have the correct voltage on the signal line.
Thank you. That’s what I surmised with what I further read after my post. Yes I did replace the resistor. At 300$ I wouldn’t say it was cheap. I agree with you I should have replaced both. It made sense to do so. Frankly my time already expended was all I had to give to satisfy my ego on repairing myself. Unfortunately at 90f with a black on black car and it’s your daily driver i need a solution quickly and i don’t have the time to tinker. All i established is i can remove a fan blower and replace it if necessary. Lol. Oh and the fact I’m not as young or limber as I once was! Lol. Took it to my independent this morning. I’m sure a new blower will fix it. Will update everyone once it’s finished.
thanks for the response.
PS interested on your thoughts as a MB tech on my next ride which I’ll get shortly. Go with a 2016/17/18 S550 again or perhaps a CLS63 possibly CLS63s. Have you any thoughts on either?
06-17-2020, 09:55 PM
