There are four basic reasons your heater may not work:
- The coolant level is low and/or the radiator cap is bad and
by not building any pressure, the coolant doesn't circulate properly.
- The t-stat is gone or stuck open. Start the engine on a cold
morning, remove the radiator cap and look inside the radiator. Raise the idle to about
2000 rpms. Is the coolant flowing or moving or is it standing still, just vibrating? With
a good t-stat, you should see no coolant flow, the coolant just sits there and shakes or
- The heater control valve is not allowing hot coolant to
circulate through the heater core OR the heater core is plugged up. This can be found by
touching the heater hoses, one or both will be much colder than the top and bottom
- There is a problem under the dash that is not allowing the
proper doors to open or close and give you heat.
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