View Full Version : Anyone know anything about the heater control valve on an '87 Mazda B-2000?
I know this is a long shot, but my 16 yr old son has an 87 Mazda B2000 and he can't get the heater core to put out heat. He has flushed the core and the water flows through it fine. He replaced the engine thermostast and that seems to be working fine, so I suspect the control valve is not letting warm coolant into the core. Where is the heater control valve on this thing? My son absolutely cannot afford to take it to a shop. Thanks.
Hot coolant flows through the heater core all the time. You could try pulling the dash and checking all the blowers, fans, vents, etc. I bet one of those is blocked off or not blowing at full strength.
Did he check the new thermostat in boiling water before he put it in? Bad thermostats out of the box are not unusual.
This might be a little late to be any help, but I have an '86. The heater control valve is near the accelerator pedal behind a large vertical dash bracket. Mine leaks a little when heating, nothing much to worry about as it doesn't wet the carpet, only collects dried coolant which I vacuum up once in a while. It hasn't gotten worse for years. The plastic control valve is directly linked to the dashboard heat lever and the rotating seal tends to leak.
I had thought the core might be leaking so I took it out for a possible solder job but the design of the core makes that just about impossible. BTW, while the core is always full of coolant, it does NOT constantly flow through the core, being throttled back by the valve. If your son smells coolant when he's trying to get some heat it means that valve is leaking. I found another valve at a junk yard but figured it might not be any better than mine and wasn't worth the trouble to install. As usual Mazda's $ for a new one was too high.
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