Ok, here is a good one. I blew a freeze plug last fall. Drivers side rear plug. (closest to firewall) The shop replaced it and " a little hose" at the same time. No more leaking coolant, but then i noticed something weird. When i turn on the temp switch from cool to warm, i smell coolant in the car. But only after the engine temp gets warm, (read, the thermostat opens) and then only for about 10 minutes. If I keep driving the smell goes away. There is no coolant on the floor, and I don't appear to be loosing any. If I'm driving around with the temp selector turned to cool, there is no smell. The heater doesn't appear to put out as much heat as before, but the longer you drive, the hotter it gets. I don't mean the actual engine temperature, but the heat that is being put out from the vents. If I put the selector to warm and drive on the interstate for an hour the car is NICE and toasty. It doesn't matter if the actual top switch is selected to heat/defrost/vent or whatever. Only the bottom switch needs to be engaged. If I have the bottom selector to cool and the top selector to vent, nice outside air comes in and no smell. If i leave the top on vent and move the bottom even 1/2 towards warm, it smells for about 10 minutes and goes away. It's not steaming up the windshield either. Do I have a heater core issue? Or did something get mis-routed while they were working on the freeze plug? ( I hope someone will tell me that it's something BESIDES the heater core! )

 

Its because the diverter valve is working, when it is on cool, it reroutes the antifreeze\water or coolant, so that it dont go thru the heater core so you can get colder air, but when on warm air, it lets it go thru the heater core, this is why you only smell it when on warm, i would pull the cover to be sure it isnt leakin, i pulled mine becuause i smelled coolant never saw any, and it was leakin, just standing in the box itself.

Kevin