My 126 heater is playing games on me ! The rear vent kicks out cold air even when the vent is closed and the fan is turned off ! The higher the fan setting the more cold air that comes through it. There must be a way to fix this. I put a new blower motor in 6 months ago and with the fan on low I get hot air and as long as I keep the fan on low the air stays hot. If I turn the fan on high it blows hot for about 10 seconds then goes cold. The same thing happens in auto climate control mode. Sometimes I turn on the heater and the fan doesn't work at all. Sometimes it works then stops working as I'm driving down the road. Sometimes I turn the heater on and I hear the sound of trickling water eminating from somewhere behing the climate control unit. Also hear a tick tock from the same place when the heat is blowing hot. As on most of these old leakers I get the smell of burning oil coming through the vents when stopped at a red light. Any fixes for this? I mean other than doing the head gasket where the leak is coming from. The valve cover gaskets don't leak any more. Any ideas are greatly appreciated.

 

The rear vent is an a/c vent only. Even when the climate control is working at its best, no heat comes from the rear vent.

As for the fan, I have had to replace my fan. It had the same problems you are talking about with it going on and off. Some of that burning smell might be the fan motor burning up. It was with mine.