Starting to get nippy here in the AMs and found out the heater is not working in my 99 Blazer.

The AC (and vents) all work great.

I was looking under the hood (around the heater hoses) for the heater control valve and can't find it! There is nothing on the hoses from the intake to the firewall.

Where is the heater control valve located ? (Didn't find it in the Search either).

 

You won't find one. There is no such device which would control the flow of coolant through the heater core. There is the temperature door actuator that is in the duct work which controls the flow of air over the heater core inside the HVAC housing. There is a gear inside which can snap causing the door to be stuck in a particular position.

 

So there's constant flow through the heater core then ?

The AC (and ducts) seem to work fine.

Is this just an issue with the temperature door actuator then ??

Also, my truck only runs around 180 degrees. Would a 195 thermostat help ?