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Mazda B-Series Climate Control
The trouble appears to be the radiator hot water does not flow through the heater core which is located in the cab directly behind the glove box.
When I’m driving the temp shows normal – indicating that the thermostat is working ok.
Last year when I also had no heat I removed the dash board and replaced the blender actuator.
I verified the actuator is working by placing an L shaped Allen wrench into the slot located on the top right of the unit and when I changed the heater control from blue to red I could see the Allen wrench swing back and forth.
I disconnected the input and return hoses to the heater core which located on the truck exterior fire wall then ran a low pressure hose - the water ran freely through the core indicating no blockage.
When I change the heater control knob I can feel the air getting cooler when the knob is moved to the blue area and a less-cool (not warm) when I turn the knob to the red area – so I’m assuming that is all working ok.
In tracing the water flow from the radiator to the heater core, I found that the radiator top hose feeds a connector that has an electrical connector on top (see below). Not sure if the electrical connector is for the instrument panel or if this is some sort of switch to allow the heated water to flow to the heater core. The water then continues out of the left side of the connector to another connector unit where 2 hoses go to/from the heater coil and 1 goes to the bottom hose of the radiator.
I guess my question is do you agree that I have a water flow problem and what could prevent the water from flowing to the heater core? Greatly appreciate any suggestions, thoughts or recommendations.