1990 Nissan Micra 1200cc cabin heater only blows cool air even when engine is up to temperature?

1990 NISSAN MICRA
46,000 MILES
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KEVMARTIN
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I have run the engine until it is up to temperature, even to the point of the electric fan " kicking in" the cabin fan will only blow cool air into the interior. Am i right in thinking that it is a faulty thermostat ? .

Many thanks

Regards Kev.
Dec 5, 2011 at 6:20 PM
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JACOBANDNICKOLAS
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No... the thermostat is designed to maintain engine temp. If it is running at normal operating temp, that isn't the problem. Test this and let me know what you find.

With engine at norm temp, turn the heater on high. Feel both heater core hoses. Both should be hot. If they are, you have a problem with the blend air door. It is located near the heater core in the HVAC box under the dash.

If only one gets hot, there isn't a flow of coolant through the heater core. If this is the case, flush and back flush the heater core to see if that helps.
Dec 5, 2011 at 6:33 PM
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RASMATAZ
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Could be the thermostat or the air blend door/actuator
Dec 5, 2011 at 6:34 PM
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