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Old Jan 4, 2018 | 02:34 PM
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In Central Fl. it's gotten cold so I used the heat. At a stop light the heater blows cool. Today I put it in N and pulled up the R's some and got heat. Any ideas???
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Old Jan 4, 2018 | 02:39 PM
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Operating temperature?
Thermostat stuck open or missing?
Low Coolant Level?
Obstruction in heater core and or hoses to heater core?
Malfunction Climate Control System?
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Old Jan 4, 2018 | 04:22 PM
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Moved to C5 Tech.
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Old Jan 4, 2018 | 07:21 PM
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My completely uneducated opinion...

We have an SUV that does the same thing. Coolant is a few years old, system has been flushed, water pump is brand new and collant is full. At idle, the heat is lukewarm. When driving (when revs are up) it is HOT.

My guess, in our instance, is that when you are at idle, the waterpump is not spinning all that fast - not much coolant being forced through the heater core. When revs pick up, waterpump spins faster forcing more (hot) coolant through the heater core.

Or - coolant level is low, and when you rev your engine it forces more coolant through the heater core.

Those are the first two things I would consider.
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Old Jan 5, 2018 | 06:27 AM
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You have air in the cooling system. Bleed the system.
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Old Jan 5, 2018 | 07:26 AM
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Having very little experience with heaters, your coolant needs to be warm first? What are your temps after five minutes? Is your cooling system in good shape?
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Old Jan 5, 2018 | 07:58 AM
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Do you have a lower temp thermostat?
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Old Jan 5, 2018 | 09:02 AM
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Originally Posted by vettenuts
Do you have a lower temp thermostat?
Good point. Not a good thing to have NOW.(a 160)
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Old Jan 5, 2018 | 11:59 AM
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Thanks everyone. I'll check the coolant level but it was just serviced. Never heard of air in the coolant. Don't think the thermostat would cause this but who knows. Operating temp seems ok.

It will warm up next week so I won't need heat.
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Old Jan 7, 2018 | 08:56 PM
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Sounds like an air bubble in the system. If you park it when the engine is warm on an incline the bubble may work its way out as the car cools down. Make sure there is coolant in the reservoir first.
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Old Jan 9, 2018 | 09:42 AM
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Any DIC codes?
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Old Jan 10, 2018 | 04:25 PM
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Originally Posted by huesmann
Any DIC codes?
Didn't pull codes. While driving the air got cool too. Something quirky, have to stop by dealer and check with my tech.
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