Heater cools down at low idle

JIMMY GARDNER

MEMBER
2009 CHEVROLET IMPALA
36,000 MILES

When at low idle heater cools down. When at speed or if you rev motor temperature will increase and work fine. But if you stop, like at a stop light, temperature will decrease. Could it be the thermostat?

5 Replies

CJ MEDEVAC

EXPERT

Is Mr. Radiator full of coolant?

(my first possible issue)

Yes, a stuck/ partially stuck open stat might exhibit the same symptom.

Radiator full, If your temperature gauge pretty much stays at operating temperature with little fluctuation your thermostat is probably fine.

Is it my low on coolant guess?

The Medic

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Friday, December 23rd, 2016 AT 6:04 PM

JIMMY GARDNER

MEMBER

Yep, it is full.

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Friday, December 23rd, 2016 AT 6:08 PM

CJ MEDEVAC

EXPERT

Ever had a new thermostat in that rig?

I believe it is a 185 degree, verify at the parts store.

Also check your heater hoses for being squashed flat/ a crimp in a bend. Replace them if they are deteriorated (as you should anyway).

The Medic

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Friday, December 23rd, 2016 AT 6:18 PM

JOHNNY G.JR

MEMBER

Possible air in system, might need to be bleed.

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Friday, December 23rd, 2016 AT 6:38 PM

SATURNTECH9

EXPERT

Are both the heater hoses going into the heater core at the firewall getting too hot to hold? If only one is then you could have a restricted heater core.