New answers tagged heater
I would check the water pump, it sounds like the blades may have corroded away. From your description it certainly sounds like the water isn't circulating.
I'm in general agreement with Ben. Cooling fan not working. The description of high vehicle speed = okay and low speed not means your fan isn't working for you. This could be a problem with fan controller, fan motor or temp sender used to turn on fan. Note, the fan shrouds matter big! Ensure they are sealed off to radiator correctly. Please check the ...
I was trying to find a picture for you but to no avail. The best thing that I can recommend is have someone turn the mode switch back and forth while you crawl around under the dash and listen for which motor is making noise. This will be external to the heater box. Once you locate the mode control motor, remove it. The motor will have a male shaft ...
Assuming the coolant is full, I'd take a look at the heater core & hoses. When the engine is up to temperature, both hoses should be roughly the same temperature. If one is cold and the other hot you can try flushing the heater core with a garden hose. A shop would be able to do a high pressure/chemical flush if the garden hose method fails.
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