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Can anyone help demystify this situation? Recently when it got cold noticed my heat wasn’t working was blowing cold air. Topped off the coolant with the Honda type 2 coolant i no change. Came to investigate the heat control valve being in the up position. Wiggled it until it seemed to move down with the car running. I get heat and cooling now in this down position so and noticed a bit of a leak. Okay sounding like it will need a replacement. My question is shouldn’t this valve be moving up and down for heat /cold? It doesn’t seem to move from the down position but the heat / cold still work. How could that be?
Up position no heat, ac works
Forced down heat / ac work fine
Last edited by thepiecesfit; Nov 14, 2022 at 07:17 PM.
In the end blend door / air mix door inside the HVAC assembly, inside the car, is responsible for mixing the air to get the temperature that you want. It still has the ability to close the airflow over the heater core, so AC will still work even with the control valve stuck open.
Only problem is that you have very hot heater core inside the cabin, so some heat will "leak" and heat up the cabin. Peak AC performance will be diminished with heater core control valve stuck open. Cheaper cars often ignore it and not use the heater core valve.
It doesn't move most likely because either it's stuck and actuator is too weak to move it, actuator is broken, or linkage is broken. Since it's leaking replace it, and then you can see if actuator moves. Or remove the linkage and see if actuator moves without resistance. As even if it was working fine before / be able to eventually open the valve, too much resistance might had broken it (it's most likely all plastic gears inside the actuator).
In the end blend door / air mix door inside the HVAC assembly, inside the car, is responsible for mixing the air to get the temperature that you want. It still has the ability to close the airflow over the heater core, so AC will still work even with the control valve stuck open.
Only problem is that you have very hot heater core inside the cabin, so some heat will "leak" and heat up the cabin. Peak AC performance will be diminished with heater core control valve stuck open. Cheaper cars often ignore it and not use the heater core valve.
It doesn't move most likely because either it's stuck and actuator is too weak to move it, actuator is broken, or linkage is broken. Since it's leaking replace it, and then you can see if actuator moves. Or remove the linkage and see if actuator moves without resistance. As even if it was working fine before / be able to eventually open the valve, too much resistance might had broken it (it's most likely all plastic gears inside the actuator).
Thanks I'll look to get the parts ordered and probably replace hoses and clamps as it's all rusted. For now since it will be cold till about February it should be okay in the open position.
I recently changed the radiator because it was bad. So i was thinking if i changed the radiator i will get more heat. Nope!!!!
heater valve changed, hosing for thermostat and thermostat changed new fluid. I realize yesterday if i push the button to make the air come out more i get a little more heat not alot.
i was told to flush the heater core and change my hoses. What do you guys think is my issue.
I had the same problem on my new to me 07. Got a coolant bleeder kit off Amazon, jacked front end up and idled it till fully warmed up, then turn heat on full hot with bleeding kit on her, hold revs at 2500 rpm to simulate flow for a minute and i got a big burp of air out of her. Heater has been cooking since 👌
