My 2011 Equinox 71000 miles on it...- The heater blows hot air only when the RPM is high - as in highway or accelerating. It blows cool air at stop lights or idling. It's winter here lol - Any ideas? I had a New thermostat installed last week by a reputable shop that says there is no problem. But clearly, there is a problem.



Kind of sounds like the impeller of the water pump is going and needs to be turning at a pretty high speed to get enough coolant circulation.

  • Then the engine temperature should rise significantly i suppose? I'd suspect a clogged heater radiator/circuit first. – Bart Jan 10 '17 at 8:11
  • @Bart - My thinking is that in the winter, there may not be as much temperature fluctuation even though the water pump isn't running at peak efficiency, also the engine coolant passages and radiators hoses probably offer less resistance than the heater so flow may be biased towards the engine. VW filters the temperature gauge so, if Chevrolet does the same thing, a moderate rise in temperature might not be noticed. But, that said, you're right any thing restricting flow through the heater core (clogging, a stuck or failed valve or the control signal to it, etc.) could also cause this. – dlu Jan 10 '17 at 16:16

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