2004 rear fan

[Gnarley]

Sounds like it did a calibration itself. That’s great.

Yeah, except it only wants to blow cold from the rear, if I leave the rear blend actuator connected. I set the flap to heat and reset the gears to stay on heat and closed it up and did not plug the connector as I determined it will not stay on the heat if plugged in, so what would cause that?

Thanks

 

[Rocket Man]

Yeah, except it only wants to blow cold from the rear, if I leave the rear blend actuator connected. I set the flap to heat and reset the gears to stay on heat and closed it up and did not plug the connector as I determined it will not stay on the heat if plugged in, so what would cause that?

Thanks

Try the calibration that I linked to in the tech section.

 

[Doubeleive]

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Just write down the part number on that rear blower resistor and take it to the auto parts store or order it online and/or take the old resistor with you to match it up at the autoparts store
99.99999% chance it is just the resistor gone bad, no sense in complicating it.

 

[Doubeleive]

Yeah, except it only wants to blow cold from the rear, if I leave the rear blend actuator connected. I set the flap to heat and reset the gears to stay on heat and closed it up and did not plug the connector as I determined it will not stay on the heat if plugged in, so what would cause that?

Thanks

watch the actuator gear on the actuator that is closest to the blower motor, when you adjust hot to cold or vica-versa you should see it rotate, if it does not rotate then replace it.
as you turn the heat adjust you should see the actuator move usually about 1/4 turn if set to a middle temp and it should stay there unless you adjust the temp more, if it rotates fine and appears to be adjusting on it's own (like to cold when you have it set to hot) then you may have a bad ambient air sensor in the headliner.

 

[Gnarley]

I followed the instructions below. Same results, the rear blend door moves to cold and will not adjust. Thoughts?

1. Start the engine and turn all the controls to the off position, (rear controls too if they're acting up), temp turned all the way down.

2. Shut off the engine.

3. Remove the positive battery terminal and leave it off for 10 minutes.

4. When it's time to reconnect it, touch it to the negative battery terminal to make sure any residual electricity is discharged.

5. Start the engine and DO NOT TOUCH THE HVAC CONTROLS FOR 5-10 MINUTES!

 

[Rocket Man]

I followed the instructions below. Same results, the rear blend door moves to cold and will not adjust. Thoughts?

1. Start the engine and turn all the controls to the off position, (rear controls too if they're acting up), temp turned all the way down.

2. Shut off the engine.

3. Remove the positive battery terminal and leave it off for 10 minutes.

4. When it's time to reconnect it, touch it to the negative battery terminal to make sure any residual electricity is discharged.

5. Start the engine and DO NOT TOUCH THE HVAC CONTROLS FOR 5-10 MINUTES!

Could have a bad ambient air temp sensor like Wes said or the actuator might be bad.

 

[Gnarley]

I previously swapped the actuators and when the blend actuator that controls the hot and cold was moved into the outlet control in the front it operated as expected and the one from the front now in the rear position controlling the blend door went right to the cold position.

By substitution both actuators are working as expected and correct. So an ambient temp sensor could do that, what about the control module or whatever the component is that tells the actuator what to do?

 

[Rocket Man]

I previously swapped the actuators and when the blend actuator that controls the hot and cold was moved into the outlet control in the front it operated as expected and the one from the front now in the rear position controlling the blend door went right to the cold position.

By substitution both actuators are working as expected and correct. So an ambient temp sensor could do that, what about the control module or whatever the component is that tells the actuator what to do?

It’s controlled from one of 2 different control heads either from the back of the console if the front one is set to Aux or from the front one if it’s not. If it’s doing the same thing no matter which control head it’s being run from then that answers your question.

 

[Gnarley]

It’s controlled from one of 2 different control heads either from the back of the console if the front one is set to Aux or from the front one if it’s not. If it’s doing the same thing no matter which control head it’s being run from then that answers your question.

It didn't answer my question, I don't know what I should consider replacing

 

[Rocket Man]

It didn't answer my question, I don't know what I should consider replacing

I doubt both your control heads are telling that actuator to do the exact same wrong thing so I would try replacing the rear ambient temp sensor. You have to partially pull the headliner down to get to the back side of it. It looks like a small fan a couple inches in diameter.
https://www.rockauto.com/en/catalog...nditioning,cabin+air+temperature+sensor,14376