Heater cools down at low idle

Tiny
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?
Friday, December 23rd, 2016 AT 4:05 PM

5 Replies

Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
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
Tiny
JIMMY GARDNER
  • MEMBER
  • 2 POSTS
Yep, it is full.
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Friday, December 23rd, 2016 AT 6:08 PM
Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
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
Tiny
JOHNNY G.JR
  • MECHANIC
  • 320 POSTS
Possible air in system, might need to be bleed.
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Friday, December 23rd, 2016 AT 6:38 PM
Tiny
SATURNTECH9
  • MECHANIC
  • 30,869 POSTS
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.
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Friday, December 23rd, 2016 AT 8:21 PM

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