The heater in my 78 GMC jimmy is givin' me TROUBLE! When it is cold and I turn on the blower motor it squeels like an SOB. It will stop after a few minutes but it is annoying! Could the squirrel cage need to be greased? Tonite it really freaked out on me and now the blower is stuck on high and stays on with the ignition OFF? I disconnected the battery for the night and am going to work on it tomorrow.Is it the switch,the resistor, or the blower motor? Or could it be all three?Any help is greatly appreciated! Oh yeah it has A/C but the pump is removed.