I've tried searching but am not having any luck. I have an 05 MCS with automatic climate control. I've noticed my ac fan varies from basically off to high on its own in manual mode, when set to high. If I put the system in auto it does very similar things, which I would assume as normal but the cabin isn't cool and the fan will drop speed. I thought that the problem might be related to electrical Load but I can be cruising down a straight road at speed and it will do it. Air flow seems low too so I am going to pull the cabin filter and see if that is clogged. Any help would be appreciated as the vehicle is new to me and I'm trying to put it in order. Also the ac doesn't feel as cool as I think it should be.

 

I'm not too sure, but it might be a sign of the fan blower motor failing. I did find this thread here on NAM where people describe theirs going in and out. If it is in fact the motor, it's a pretty big job. Maybe someone can chime in with another suggestion?

 

Thanks. The fan does have a high pitch whine. So that might be it. Luckily I have an extended warranty on it.

 

Anytime. When you get it check for the warranty be sure to update the thread and let us know if that ends up being your issue. Good luck!