HVAC mode actuator not working properly

Hi,

There could be an issue with the power supply, a wiring issue, or even a ground issue.

Below, I attached a pic from the wiring schematic specific to the mode door. Check the voltage signals indicated. Also, confirm there is ground as well.

Let me know what you find or if you have other questions. Also, here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-wiring

Let me know what you find.

Take care,

Joe

See pic below.

I checked the voltage of each pin:
5: 4.72
6: 0
7: 3.40
8: —
9: 0
10: .89

After this I checked the resistance from the pin that connects to the mode actuator to the pin the plugs into the back of the control module. Pins 6 and 9 both showed 0.4 for resistance (which is acceptable as far as I know). I’m not really sure what to make of this. I’d appreciate it if you could point me in a direction to go next.
Thank you.

Hi,

The voltage is too low. Pin 10 should have a 5v reference. You indicated it is .89v. Trace the wire (pin 10) and inspect it for damage, corrosion, or a short to ground.

Let me know what you find or if you have other questions.

Take care,

Joe

So I made some more progress but still not there…

I checked the resistance on pin 10 and it was something well over 1. I just replaced the wire and now have resistance of .04. However the voltage has not changed it is sitting at .94 volts now. I used a slightly larger gauge wire than the one that was already wired into the harness since that’s what I had at the house. Not sure where to go from here. Thank you for the help so far!

Hi,

I attached the wiring schematic below for the system. I highlighted several wires that are relevant for you.

Now, since the temperature actuators are working, we are getting power to the instrument junction box. Since you are still only getting .94v at the light blue/black wire, the issue is likely at the junction.

If you look at the last pic below, I have an arrow showing how power gets to pin 10. If this is the one you replaced, go back to the junction box and see if there is power there.

The problem seems to be from pin 10 voltage.

Let me know what you find.

Joe

See pics below.

Hey Joe,

Sorry for the delay. What/where would I find the junction box you are referring to here?
Thanks!

Hi,

It's at the end of the dash on the right side. See pic 1 below.

Let me know if you find it.

Take care,

Joe

See pic below.

I located to junction box and found the blue/black wire that matches the one I cut and replaced behind the HVAC module. I am not getting any power from the wire at the junction box (first picture). Other wires are getting power at the junction box.

I am also assuming that the wire I cut behind the module will need to be spliced back in to provide the power? This can be seen in the second picture.

The connector block that plugs in on the other side of the target wire has power everywhere except for the three wires circled. One is purple/white, and the others are the main black and red ones.

The blue wire with the black tracer (the one you repaired) should provide a 5v reference. The idea you have no power is causing the mode door issue.

You need to go to the HVAC control module and check for a 5v reference right at the module. If there isn't one, chances are the module is bad.

I attached a pic below showing what and where to check. The idea that this wire has already been fixed indicates there could be an issue with the wire and not the module. That's why I'm recommending checking right at the module.

Let me know.

Joe

All right so I made some progress. There was 5volts at the module. I realized that I had cut the wire that ran to the junction out of the equation when I replaced the wire from the module. With the 3 loose ends spliced together I now have power to the mode actuator.

Only issue is that when I turn the key the actuator puts itself in the position shown in the image. After it moves to this position, I can’t get it to move anywhere else using the buttons on the module. I have reset it with a 9V battery but each time I plug it in it goes to this position and freezes.

Does it move when it's not attached or connected to the mode door?

Let me know.

Joe

I haven’t fully installed it. I just had it sitting on the floorboard next to the gas pedal. Plugged it into the harness and tried different functions and it wouldn’t move.

Hi,

Okay, if it isn't installed yet, let's try something. Disconnect the connector on the actuator. Next, check for power signals on the brown wire and the tan wires while changing the mode switch.

Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-wiring

Also, make sure fuse HVAC 1 in the under-hood fuse box is good.

Let me know,

Joe

The HVAC fuse is good. The brown wire had a constant reading of 12V, and the tan wire had a reading of 2.5V. The voltages did not change when I cycled through different modes using the mode switch in the HVAC module.

The yellow and green wire were showing about .02V and did not change when I cycled through modes. The blue wire is still holding its 5V ref.

Hi,

When you checked it, did you use the green and yellow wires as a ground?

Joe

Originally no, I did not use the green and yellow wires as ground. I just checked again using these wires and the readings were the same and there was no change in voltage when I changed the mode. The only thing that was notable was the voltage was slightly lower (about .05V) when using the green wire as the ground.

The voltage should be changing. I'm questioning if the HVAC controller is bad. Are you able to test the same wires right at the controller? Or maybe you already have. I'm suggesting this because if the fuse is good, there is battery voltage to the controller, but it doesn't respond, the controller itself must be bad.

Let me know.

Joe

I just tested the wires right at the controller and got the same results. Also, just to confirm you are referring to the 10-amp HVAC/ECAS fuse under the hood correct?

Hi,

The fuse I believe you are referring to should be in the interior fuse box. It is the HVAC 1 fuse.

Take a look at the pic below. I copied that from an earlier pic I sent.

Let me know.

Joe

I checked the fuse, and it looks good. I will look into buying a replacement HVAC module. Is there a certain brand that you would recommend?
Thank you for all the help!

Hi,

As far as the module, I'm not sure they are manufactured "new" by an aftermarket company. Oftentimes, they rebuild them, or the part is only available via a dealer. However, since it's an 05, you should be able to find a remanufactured one. Just make sure there is a warranty with it.


When you checked the fuse, are you sure there was power to and from it?

Let me know.

Joe

The fuse is definitely good. Of the two holes that the fuse plugs into one side had 12V and the other had .033v. Not sure if that is what it should be. If that all checks out, then I’ll order a new unit.

Hi,

When checking the fuse and you got that reading, was the fuse installed? You should have 12v on both sides.

Joe

No, the fuse was not installed. To check with the fuse installed would I need to find the brown wires from the diagram you sent me?

You should be able to reach both sides of the fuse. Also, that's why you only had power on one side. With the fuse being out, there was no power transfer to the opposite side. Take a look through this link and let me know if it helps.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Let me know.

Joe

Hi Joe,

I’m sorry for such a delay but I’m back on the project. So, I ended up getting a new HVAC controller unit. I hooked it up and nothing has changed. I just thought I’d check in and see if you had any other ideas. Thank you for all of your help I really appreciate it!
Zach

Hi,

No problem with the time delay. I know what it's like. LOL As far as the controller, if it has power and ground, it should work. Have you rechecked that?

Let me know.

Joe

yes, it has ground and power. All of the controls work on it - I can control fan speed and whether I want heat or A/C. I plugged the mode actuator in, and it will not change position when I switch between modes on the controller. So, I'm essentially in the same situation I was in before getting the new controller.

I may just get a new mode actuator, but I don't really think that's the problem considering I can control it with a 9V battery.

Before getting a new actuator, take a look at the pic below and check for voltages at the actuator connector. Also, check the low reference for continuity to ground.

If you have nothing there, we have an open or bad signal, which I doubt with the new controller. If you have the power indicated and ground, then it is most likely related to the actuator.

Let me know.

Joe

Good news we got the actuator to start responding to the controller. I’m not really sure what the problem was. I was just messing around with plugs and fuses, and it suddenly started working. Thank you for all the help!

I’m having some trouble getting it reinstalled now. I’m not sure which way the cam should be facing in order to make installation the easiest. If you have any tips, I would appreciate it. Otherwise, I’m sure I’ll be able to figure it out.
Thanks again!

Hi,

I'm glad to hear it's working. You must have a bad connection. Make sure the connectors are tight and undamaged. Also, make sure the fuse, where it plugs in, didn't move the connector pins.

Let me know. Also, I attached the directions from the manual below for installing the actuator.

I hope this helps. Let me know.

Joe

See pic below.