Hey Team..... Sorry for another heater question, but it is cold!

My heater is just not blowing hot. AC is working fine and all the vents are working (I can move between feet, face etc)

I have read around and will try a few things, but wanted to start a chat here to go through things.
If you do have a fix, can you please be as descriptive as possible, or link a video (I am not super car savvy).

I am running a 99 Classic.

Thanks in advance!

 

It may have a faulty blend door actuator. That's the part that moves the blend door and mixes cold air with heated air and works from the temp control. It's an electrical stepper motor and is right behind the glove box. If the door gets stuck, it can shear the plastic shaft, then usually the door will drop into the defrost position, but not always.

 

Cheers!

I am hoping I just need to flush the heater core and it isn't the blend door, as the blend looks like a mission to get to.
I will also check to make sure my heater hoses are hot and there is air moving.

 

So I flushed the heater core and I am now getting warm/hot air, but it is not SUPER hot.

When I flushed I didn't have the heater on (car not running), will it make a difference if the heater is on (car not running) when I flush?

All the pipes are hot.

Cheers!

 

Also, I don't see a cable that moves the blend door....?

 

I also have a 99, there is no cable for the blend door, it is electronic control. Look under the dash on the passenger side and you will see the blend door actuator (Black box) held in place with 3 or 4 screws and a electrical connector connecting to it.

As for flushing your heater core, disconnect the supply and return hoses and gently back flush into core return line with a garden hose, I say gently as you do not want to use much pressure or the core could develop a leak. Just low water hose volume and pressure and let water pass through the core for several minutes to back flush any crap out.

 

The blend door is moved by a stepper motor, that's an electric motor that moves a certain number of degrees every time an electrical pulse is fed to it. Let's just say the motor is divided into 36 segment. The motor shaft will move 10* each time it gets a pulse. You can almost feel the steps in the temp control when you rotate it.

 

How hot are your heater hoses compared to the radiator hoses?

Not as hot? flush the core again.

same temp? You need the correct thermostat.

 

Could also be a stuck open thermostat.

 

Thanks man!

The heater hoses are cooking, but I have not checked the radiator hoses yet.... I will this arvo when I head out.
At this stage I am getting hot air, but not SUPER hot. It still gets to the point where I need to turn the heater down/off, but it doesn't burn my bare feet.

Maybe that is due to it being a 20yr old truck....?

 

Thanks for getting back mate.

As per my last reply....
At this stage I am getting hot air, but not SUPER hot. It still gets to the point where I need to turn the heater down/off, but it doesn't burn my bare feet.

And yeah, maybe it is due to age.

Cheers.

 

Get a thermostat or thermometer and check what temperature the heat is coming out of the vents. All Jeep owners have different definitions of hot air (mainly because we are all full of it).

Also, probably wouldn't be a bad idea to flush the entire cooling system while you are at it, and make sure that you purge all the air out of the system.

Replace the thermostat with a Mopar one if you can get it, (have you ever replaced the thermostat before? Could a previous owner have put a lower temp thermostat in)

 

If I feel my heater is inadequate, I stop at Taco Bell and get 2 bean burritos to go.

 

Two of those and my driver seat will need some upholstery work.

But seriously, give the cooling system a good once over while you are checking everything.