Heater blowing cold air

Hello,

It sounds like you have a clogged heater core or an air pocket stuck in the core check out this guide that tells you how to fix the heater.

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

Also it could be the temperature blend door actuator is not working right here isa guide that will walk you though the repair with diagrams below to show you how the job is done.

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

Check out the diagrams (Below). Please let us know what happens.

Cheers

Sounds like the temperature blend door actuator (air mix servo) stopped working but to be sure this guide can help us with the actuator location in the diagrams below.

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

Check out the diagrams (Below). Please let us know what happens.

This is automatic temp control and the only way to properly diagnose this is to have a local pro put his scanner on it to see If there are codes. Which means a sensor can be bad inside or outside car causing this. If you follow the chart on the lh side it may give codes to which we can get back with your on what to check. You can also try pulling the ecu-b fuse inside car to see if that resets actuators to get heat. And then check fuse and relay in pic under hood.

Attached are the codes and fault. Forget about code 21 first. It is for the solar sensor and would show up if you are working under the shade.

Good evening.

It sounds like it has a clogged heater core.

What I would try is to remove the hoses from the core and then use a garden hose and run the water through the core. Run it both ways until you get a good clean flow from both sides.

If it comes out good, then hook them back up and try it. If it works, you are good.

If it does not, then the heater core will have to be replaced.

Roy

Hi and thanks for using 2CarPros.com.

If only one of the hoses is hot, then coolant is not flowing through the core. What I suggest is to disconnect both heater core hoses and try to flush water through it to clean dirt and debris that may be blocking it.

Also, here is a link that shows the most common causes of no heat. Look through it to see if it is helpful.

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

Let me know if you have other questions or if this helps.

Take care,
Joe

Hi, since both hoses are getting hot as you indicated, then there is flow through the heater core. Based on that, you are most likely correct. You referred to the blend air door. Toyota calls them an air mix control servo motor. That is the next thing that should be checked for operation.

I have attached two pictures for you to look at. The first shows all components under the dash. The second shows where the servo motor is mounted on the HVAC/heater box.

Let us know if this helps.

Take care,
Joe

If you get a response out of other vent positions ( face, defrost) then the source vacuum is probably ok. Sounds like a actuator door problem under the dash. Might want to look under there to see what moves when you select different vents, could help pin point the problem door.

This guide can help us find the problem.

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

Please run down this guide and report back.

Heater Core "” Plugged

WARNING: The heater core inlet hose will become too hot to handle if the system is working correctly.

Check to see that the engine coolant is at the correct level.
Start the engine and turn on the heater.
When the engine coolant reaches operating temperature, feel the heater core inlet and outlet hose to see if they are hot.
If the inlet hose is not hot:

the thermostat is not working correctly.
If the outlet hose is not hot:

the heater core may have an air pocket.
The heater core may be restricted or plugged.
If both are hot, the temperature blend door in the heater plenum may be broken or stuck.
On some occassions, the water pump may have impellers that have disolved, creating your symtoms exactly.

Since heater core is hot suspect and check blend door operation.