Whistle sound when using heater (1 Viewer)

[ariff]

So I have had this little problem for the last few years. When I use the heater in any position I hear a loud whistling sound. Now when I move the temp selector to cold the sound goes away. So I am thinking it is a seal on the blend door. As of now I have been solving the problem by turning up the radio ;>) But I was wondering how hard it might be to troubleshoot that blend door? I am not sure where it is located or if it is easy to get to.. Anyone have any thoughts?
Thanks!

 

[blkprj80]

How is your heater valve on the firewall in the engine bay?
Moving the temp selector changes the position of that valve. It doesn't move blend doors.

 

[ariff]

It is fine heat works great just has a loud whistling noise when the heat selector is all the way hot. When moved to cold no whistle... I would think there is some sort of door that moves to allow air to blow over the heater core when hot and Evap when AC is selected? Maybe not?

 

[blkprj80]

Maybe there is. I'm not sure but I do know the valve moves following that lever.

 

[1911garand]

How is your heater valve on the firewall in the engine bay?
Moving the temp selector changes the position of that valve. It doesn't move blend doors.

Not sure if that is 100% correct. I totally removed / bypassed the heater valve - gone. The temp selector DOES move the blend doors because I get heat and cold air by sliding the temp selector (even with the heater valve in the garbage can).

Is the noise coming from the blower motor? When the bearings get old, they can make some strange noises.

 

[Jgrauman]

The heater valve allows the heater core to receive a flow of warm water to heat up. The blend door allows the air to flow over the core. If you remove the valve you would just receive some passive heat from the core of you don't have it on heat.

 

[ariff]

Not sure if that is 100% correct. I totally removed / bypassed the heater valve - gone. The temp selector DOES move the blend doors because I get heat and cold air by sliding the temp selector (even with the heater valve in the garbage can).

Is the noise coming from the blower motor? When the bearings get old, they can make some strange noises.

I don't think it is coming from the motor.. If that were the case it would make the noise when the temp selector was in the hot or cold position. And it only whistles in the hot position..