I have a 2004 Chevy Suburban that had no heat in the front or rear at idle. I found this mechanics stack exchange article, discovered I was low on coolant and now I have heat in the front when idle but still no heat in the back.

Any thoughts would be appreciated.


You need to purge your cooling system.

  • Raise the front of the vehicle with a jack or ramps. Driving up a sidewalk works too.

  • With the engine cool (when you touch it it should be cold): Remove the radiator cap.

  • Run the engine.

  • Turn on the heater.

  • Accelerate the engine to 1500-2000RPM.

  • You will see the coolant level go down and/or bubbles. Pour in some new coolant until the bubbles stop and the level does not decrease. This might take a couple of minutes.

  • Turn engine off.

  • Repeat in 30 minutes if you are obsessive. Otherwise put the radiator cap back on. You are done.

Whats happening is that you have air in the system. That air is not letting the rear heater core receive hot coolant. By purging it you are removing air trapped in the system.

Note: If you have pets (dog or cat): Don't let them drink the coolant that might fall on the floor. It is lethal for them. It smells sweet and they will be tempted to drink it.

| improve this answer | |
  • Does a Chevy Suburban 2004 have a radiator cap? Perhaps I'm just not seeing it because its covered. All I see when I open the hood is the cap for the relief container. – Buska Jan 4 '16 at 21:15
  • Yes, thats the radiator cap. :) – race fever Jan 4 '16 at 21:45
  • +1 for dog safety. Wish I could +1 again for the rest of the answer :-) – DucatiKiller Jan 5 '16 at 1:45

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