Heater is not working?

Good afternoon,

Sounds like the system has dirt and debris in the system.

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

I would remove the hoses from the heater core and use a garden hose and flush the core back and forth. Run it until you get a good flow from both directions.

I would also flush the cooling system as well.

https://www.2carpros.com/articles/coolant-flush-and-refill-all-cars

Roy

I flushed the heater core and radiator with a garden hose and also used some Blue Devil and let it circulate and replaced with fresh coolant. The car gets hot in the driveway but after 10 minutes the heat goes cold. When I park it the heat will return in a few minutes. Think the new thermostat is stuck or what?

I doubt it.

Has the engine ever overheated?

The additive you used is not good. It clogs up the passages in the radiator and the heater core.

Are both hoses hot at the firewall when it does not have heat?

Roy

Engine has not overheated. Yes, both hoses get really hot at the firewall. Upper and lower rad hoses also get tight and very hot.

This points directly at the heater core as the failure.

You have hot hoses and heat above idle. You have a clog in the core that slows the circulation.

Roy

WARNING:
- ON VEHICLES EQUIPPED WITH AIRBAGS, DISABLE THE AIRBAG SYSTEM BEFORE ATTEMPTING ANY STEERING WHEEL, STEERING COLUMN, OR INSTRUMENT PANEL COMPONENT DIAGNOSIS OR SERVICE. DISCONNECT AND ISOLATE THE BATTERY NEGATIVE (GROUND) CABLE, THEN WAIT TWO MINUTES FOR THE AIRBAG SYSTEM CAPACITOR TO DISCHARGE BEFORE PERFORMING FURTHER DIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE WAY TO DISABLE THE AIRBAG SYSTEM. FAILURE TO TAKE THE PROPER PRECAUTIONS COULD RESULT IN AN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL INJURY.
- IF THE VEHICLE IS EQUIPPED WITH AIR CONDITIONING, REVIEW THE WARNINGS AND CAUTIONS IN THE FRONT OF THIS SECTION BEFORE PERFORMING THE FOLLOWING OPERATION. See: Heating and Air Conditioning > Technician Safety Information

1. Remove the HVAC housing. Refer to Housing Assembly HVAC/Service and Repair/Procedures See: Housing Assembly HVAC > Removal and Replacement > HVAC Housing - Removal and Installation

Fig.14 Heater Core Removal/Installation
imageOpen In New TabZoom/Print

2. Remove the two heater core retaining screws (if equipped).
3. Gently push back on two of the heater core retaining tabs and pull up on heater core to remove.

INSTALLATION

WARNING: IF THE VEHICLE IS EQUIPPED WITH AIR CONDITIONING, REVIEW THE WARNINGS AND CAUTIONS IN THE FRONT OF THIS SECTION BEFORE PERFORMING THE FOLLOWING OPERATION. See: Heating and Air Conditioning > Technician Safety Information

1. Install the heater core into the top of the HVAC housing.
2. Push on top of heater core until all for tabs are locked into place.
3. Install the two heater core retainer screws.
4. Install the HVAC housing. Refer to Housing Assembly HVAC/Service and Repair/Procedures

Some guys let CLR sit in heater cores for clogs. How do you feel about that?

I have never used any product that breaks up clogs from rust. You could try doing it again with shop air and a garden hose. I think I would give it a second shot before pulling the trigger on a heater core. These are a pain to replace. I have bad memories doing these.

Roy

I've already done the garden hose method. Water comes out both ends just fine, clear.

Okay, if both hoses are hot, the blend door is working back and forth, the only thing left is the core itself.

https://www.2carpros.com/articles/replace-heater-core

https://www.youtube.com/watch?v=-xnM-K5A3ow

Roy

Just humor me. Could it be that the system still isn't bleed correctly? These have those little bleed valves at the upper rad hoses. Maybe I'm doing something wrong.

Those valves are to be opened only when filling the system. The engine cannot be running or it will draw air into the system.

To bleed it, run the engine at 1,200 RPM's with the cap off. Wait until the thermostat opens and you get heat. Monitor the level and keep it full. Once you have good heat, install the cap and return to idle.

Roy

What about a heater control valve?

There is no heater control valve in the hoses as in the older days. The heat control is handled by an actuator or door that allows heat or shuts it off.

Roy

Well, I attached two hoses to the core and added some CLR. Which is clear. One bottle is 28 oz and I almost used it up. It's okay to see the green color even though I flushed it before adding right? Since the additive is clear? I'm going to let it sit overnight.

Okay, let us hope it breaks up the dirt and debris in the core.

Roy

So I flushed the CLR out of the core and here's what happened:

I got the car to get heat, my vent gauge showed 109.8 F, ambient temp today was about 70 F with 100% humidity.I drove it for 5 miles and the temp went down to 90 F, basically feels like slightly warm air. When I parked it at the house, the temperature started climbing again.

Sounds like it worked.

Drive it for a while and see if it gets better and stays at the 109.

Roy

I'll check the coolant level in the morning and see if itll get hot again. Maybe the ambient temp is making it difficult. The 90 F air really didn't feel too warm but wasn't exactly cold

So you're saying it's normal for the heat to go way up in park and down nearly 20 degrees while driving?

No it's not normal. You still may have some dirt and debris in the core.

Roy

I heard I might need to bleed the system with the front end lifted. Maybe that could work.