Heat not working well in extreme cold

[Sylar]

So I've noticed my heat doesn't work very well when the temperature drops below freezing and the colder it gets the worse it works. Also when it's cold it only works when the RPMs are up higher, at idle I get no heat at all. I was reading it could be air bubbles in the cooling system when your levels aren't topped off and I do know I have a small leak in my coolant reservoir, but even when it's topped off I still get this problem. I was wondering if anyone could point me into the right direction on as to what the problem could possibly be. I plan on replacing the reservoir and flushing the whole system very soon, but was curious if the problem could be somewhere else. Thanks.

[nsprosty]

I'd start with replacing that reservoir. It's a 10 minute job that requires almost no tools and the part can be found for around 25$. Its possible that its sucking air in through the hole in the reservoir.

Although I doubt that's the reason its not producing the heat you want.

[daught]

Air in the heater core or clogged heater core. You did not top up the leaky coolant with green coolant, right?

[Sylar]

Air in the heater core or clogged heater core. You did not top up the leaky coolant with green coolant, right?

Nope, always use G12 coolant.

[fyremanpat]

probably clogged heater core. i had the same symptoms. i just replaced mine last week. HUGE difference!

[old guy]

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