Heater not working?

Good evening,

When he had the blend door off, did he verify the door was actually moving back and forth?

https://www.2carpros.com/articles/replace-blend-door-motor

Are both heater hoses hot to the touch with the engine at normal operating temperature.

https://www.2carpros.com/articles/car-heater-not-working

He is correct, there is no heater control valve in your engine.

I would also, remove one of the hoses while running to see if there is flow to and from the core to be sure there is circulation.

Roy

Thank you, Roy. After he replaced the blend door, it seemed to work, but then we had that record breaking week of 75 degree temperatures, so hard to say for sure. My mechanic is usually quite thorough.
I will have to wait until Monday to ask him those questions. He said he needs to clear his head this weekend. He wants to ponder over it until Monday. He is not used to being stumped.
What really has us stumped is that the heater blows medium warm air when idling.

Yep, sounds like a circulation issue.

Roy

What would cause that?

The hoses may have debris inside causing the coolant to be restricted and no flow the proper amount of coolant. He needs to check all the way back to the intake manifold.

Roy

Hi,

I hope you don't mind me jumping in. Roy is correct saying it is likely a circulation issue. Here is an easy way to check:

Start the vehicle and turn the heat on high. Allow the engine to run until it reaches operating temp. Then you can turn the engine off. Open the hood and feel both heater core hoses. Both should be hot (one may be slightly warmer simply because it is a supply line). If one is cool and one hot, there is a circulation issue.

The heater hoses are behind the engine and attach to the heater core. They are rubber hoses approximately 1" in diameter. See attached pic.

Also, let us know if the engine is reaching operating temperature.

Here are the bleeding directions. There is a bleeder on the thermostat housing. I'm not sure if that is what you are using.

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1. Fill the radiator and the coolant reservoir to the full cold line with GM Goodwrench DEX-COOL (R) or Havoline DEX-COOL (R). To ensure sufficient engine cooling, freezing and corrosion protection, maintain the protection level at -37°C (-34°F) lower.
2. Wait for two minutes and recheck the level of the coolant in the radiator. If necessary, add coolant to radiator until the coolant level is at the base of the radiator fill neck.
3. Install the radiator pressure cap, making sure the arrows on the cap line up with the coolant recovery tube.
4. Place the heater and A/C control in any A/C mode except Max and the temperature in the highest setting.
5. Start the engine and allow to idle until the louver radiator to coolant pump hose is hot.
6. Cycle the engine speed up to about 3000 RPM and back to idle five times. Slowly open the bleed valve on the top of the thermostat housing for approximately 15 seconds to expel any trapped air in the cooling system.
7. Close the air bleed valve. Do not overtighten.
8. Allow the engine to cool to outside temperature. Ensure the coolant level in the reservoir and the radiator are at the proper levels.
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Let us know what you find or if you have other questions.

Take care,
Joe

I flushed the heater core I think that did it, thank you so much I have heat again!

I guess I thought the system flush would have cleared the hoses.

You are welcome.

Always glad to help.

Roy