Mechanics

WHY DOES MY TEMP GUAGE FLUCUATE AND HEATER ONLY WORK WHEN REVING AROUND 3 K RPMS

1994 Mazda b4000 • 84,000 miles

Replaced thermostat temp sending unit and flushed coolant system. The truck reads hot when driving and heater blows cold but when u rev it to 3k rpms it drops to normal operating temp and the heater starts to blow warm again
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Tnorth3
January 6, 2012.



Sounds like the heater core is restricted I would check athat first. Unless you are low on coolant or have air in the cooling system?

Saturntech9
Jan 6, 2012.