Jim Grant's Tech Tips

'93 Mazda MPV, The Worst Heater

Q: I have a ‘93 Mazda MPV 4WD van it is a V-6 3.0 and it has the worst heater I have ever seen. This is the 1st winter I had it, and may be the last. I flushed the system, and replaced the thermostat, also replaced the radiator with a brand new one, put a brand new water pump and new 13lb. radiator cap as well. All this work was done to end up with a heater that does not put out more then a very little heat and I mean very little. What else can I do to it, so my wife can see this winter to drive it to work? Any help will keep peace at the table in the morning......Allen Schaffner

A: The way the temp’s been dropping in this area I would not want to be across the breakfast table from my wife if her vehicle did not have heat. My mother inlaw, that’s a different story. She could use having her rockets cooled down just a bit. If coolant flow is good through the heater core and the engine is at the correct operating temperature then I would question the positioning or the gaskets of the temperature blend door. The temperature blend door directs the flow of air over the heater core. If the gaskets on the door are worn or missing, the door is mispositioned or broken it will allow cold air to enter the passenger compartment. The result would be the chilling of the love of your life. This can have a chilling repercussion that can go far beyond the breakfast table. If all else checks good misdirect air flow could be the problem.