I have a question about my 2009 hyundai elantra heating issues. at first the switch wouldnt turn on until i started driving the car and it blew out cold air. They changed the fan relay (?) switch. After that the switched turn on when i started the car. However, after warming the car up for 45 mins its only slightly warm? They now changed the gasket, blower motor resister & the thermostat. And they also did a heater core flush. As of now, when I start the car the air is cool, after driving the car for a while the heat will work well, but when i stop at a traffic light cool air comes out? And then when I hit the gas again to drive the heat comes back on. Can it be the blend door actuator?
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Hello,
I'm more concerned about your water pump.
If the water pump fins erode, they will pump water when the engine is moving fast (driving), but not when the engine is moving slow (idle).
Really, that is exactly what this sounds like, but I would have the dealer sort it out under warranty (if you still have warranty remaining). You would also have a clogged up heater core that is requiring more pressure to push coolant through, but that is not very likely.
As for the blend door: it would have to be completely separated from the actuator, and swinging closed as you stop and swinging open when you accelerate.
If that were the issue, you could just pull up and stop facing upwards on a very steep slope and the air should stay warm, while driving down a very steep slow would cause cold air. You should at least have a little fun with the issue and try it out.
