Yes, the noises stop
Yes, the noises stop consistently when the 'O' button is pressed, so they are definitely heater related. Wasnt just this one time, but this problem has been going on for about 10 days. I checked for cracked fuse in the heater related fuse (#7) in the fusebox under the hood and it is OK. Noted that the blower fuse is located elsewhere, but couldnt find it. Could you tell me where it is?
Also, since I bought this car about 2mos ago, it has made a whirring noise on start up that goes away within about a minute. I thought it was normal, but now I am wondering.... I know that the car had the head gasket replaced while it was at the dealer between the time that it was traded in and the time that I bought it. I am wondering if there could have been some debris introduced into the cooling system at that time and that could account for the whirring (debris hitting the water pump) and the noises and problems in the heater? Would the fan blow if the heater core was temporarily blocked by debris? Or could debris mess up the coolant temp sensor fooling the blower into thinking the coolant is too cool for the fan to operate?