New Blend door actuator not working

[papa t]

Hey there! New member here in AZ.

I have a 99 EB 5.4 with EATC climate control. I replaced the heater core that had been leaking severely. When I got the dash back on I adjusted the controls with the engine running while watching the blend door actuator under the dash. it moved but not as much as I thought it should. So I drilled an "inspection" hole behind the glove box and into the plenum cover. I watched the blend door open and close when the hot/cold buttons were adjusted, but the movement was intermittent. I'd checked the blend door for cracks prior to installing the heater core and found none. I left things alone for a day while I drove as normal. When I had time to work on it again, the actuator quit working. I figured it was damaged from the coolant leaking into the cab so I decided to replace it. It was indeed full of coolant. I bought a Dorman actuator (part #604-216) and plugged it into the wiring harness to test it before installing it. I adjusted the controls with the ignition in the "run" position and nothing happened. I'm at a loss as to what could be the problem. I've searched for this problem, but the only threads I find are incomplete or deal with the "manual" controls. I checked all my fuses and they are all good.

My questions are:

Could I have bought the wrong actuator? Would the harness fit the "manual" actuator? The part number was identified as being for the main blend door for "automatic" controls.

Is there a possibility the EATC head unit is bad? It still sends air to the panel, floor and defrost when adjusted.

How do I test the voltage at the connector? I just bought a multimeter but I'm not sure which wires in the harness deliver power to the actuator.

I know there are a lot of people on this site who've gone through the heater core/blend door ordeal and have lived to tell about it. I'd appreciate any advice as to what I should do next.

Thanks in advance.

 

[maverick]

Hey there! New member here in AZ.

I have a 99 EB 5.4 with EATC climate control. I replaced the heater core that had been leaking severely. When I got the dash back on I adjusted the controls with the engine running while watching the blend door actuator under the dash. it moved but not as much as I thought it should. So I drilled an "inspection" hole behind the glove box and into the plenum cover. I watched the blend door open and close when the hot/cold buttons were adjusted, but the movement was intermittent. I'd checked the blend door for cracks prior to installing the heater core and found none. I left things alone for a day while I drove as normal. When I had time to work on it again, the actuator quit working. I figured it was damaged from the coolant leaking into the cab so I decided to replace it. It was indeed full of coolant. I bought a Dorman actuator (part #604-216) and plugged it into the wiring harness to test it before installing it. I adjusted the controls with the ignition in the "run" position and nothing happened. I'm at a loss as to what could be the problem. I've searched for this problem, but the only threads I find are incomplete or deal with the "manual" controls. I checked all my fuses and they are all good.

My questions are:

Could I have bought the wrong actuator? Would the harness fit the "manual" actuator? The part number was identified as being for the main blend door for "automatic" controls.

Is there a possibility the EATC head unit is bad? It still sends air to the panel, floor and defrost when adjusted.

How do I test the voltage at the connector? I just bought a multimeter but I'm not sure which wires in the harness deliver power to the actuator.

I know there are a lot of people on this site who've gone through the heater core/blend door ordeal and have lived to tell about it. I'd appreciate any advice as to what I should do next.

Thanks in advance.

I had the same problem. Found out the parts store gave me the actuator for a manual heater control. I switched to the automatic one and it worked like a charm. Let us know how it goes.

 

[papa t]

Thanks for the quick response. You don't happen to know the part number and make of the "right" actuator by chance?

 

[walnuts4x4]

try contacting our vendor "tasca parts or Rockauto" if you can find the part #

 

[papa t]

I monitored the actuator to see if the axil moved at all over time. Nothing happened. I've got continuity of the wires to the head unit but only .64 volts at the actuator. It does fluctuate when the engine is running and the controls are adjusted, but not by much. Checking the power at the EATC head unit showed about the same. My next thought is to pull the fuse panel and see if there is a problem there.

I'm struggling with making sense of this though. It seems way too coincidental that the only electrical problem I'm having after pulling the dash for the heater core is the power for the actuator. The old actuator was working briefly after the dash was reinstalled. Could there be a ground behind the dash that I damaged?

I'm going to order another actuator to double check that it's not the problem. I may also order the actuator for the manual control to see if the part numbers are wrong.

I'm open to any and all thoughts or suggestions.

 

[papa t]

Does anyone know what the voltage at the EATC head unit and at the actuator should be? Also, the back of the head unit has two wire harnesses. I'm presuming that one is the power and other connections to the unit and the other is the connections out of the unit. Am I close to being right? Any help with what each of the colored wires is would also be helpful.

 

[maverick]

EATC Wiring diagram

 

[maverick]

This is the same vehicle I have. Currently having problems with no heat. All actuators work on this one. I have the workshop manual if you need any other diagrams or install/ removal info.

 

[papa t]

Thank you very much for the diagram Maverick. I really appreciate it. Do you have a diagram showing the wires to the blend door actuator?