(Another) HVAC actuator post

[Apach 031]

Hey folks. Another HVAC post. I haven't seen this exact same issue discussed before. As the weather warmed up this spring, I noticed my AC light was blinking, and wouldn't engage. Further investigation revealed I couldn't changed the mode at all. Stuck on heated defrost.

So far, I have changed out the recirc door actuator and mode door actuator. And the HVAC control unit. When I hook up the tech 2, it gives me B0423, B3779, B0228, and, B0413, all symptom 61. When I use the tech 2 to try and command them to change position, they won't budge, but all of the rear actuators work fine. When I do a recalibration, nothing changes. I was having the same issues with the old and new HVAC control unit.

I installed a new head unit over the winter, and thought maybe a messed up a connection to the control unit. Traced all wires back to the actuators and checked plugs...they seem fine. In I should mention that when I switched out the recirc actuator, it was out of range. But I have triple checked the new one, it's still within range, and won't budge.

I'm at wits end. Any ideas?

 

[Apach 031]

Hey folks. Another HVAC post. I haven't seen this exact same issue discussed before. As the weather warmed up this spring, I noticed my AC light was blinking, and wouldn't engage. Further investigation revealed I couldn't changed the mode at all. Stuck on heated defrost.

So far, I have changed out the recirc door actuator and mode door actuator. And the HVAC control unit. When I hook up the tech 2, it gives me B0423, B3779, B0228, and, B0413, all symptom 61. When I use the tech 2 to try and command them to change position, they won't budge, but all of the rear actuators work fine. When I do a recalibration, nothing changes. I was having the same issues with the old and new HVAC control unit.

I installed a new head unit over the winter, and thought maybe a messed up a connection to the control unit. Traced all wires back to the actuators and checked plugs...they seem fine. In I should mention that when I switched out the recirc actuator, it was out of range. But I have triple checked the new one, it's still within range, and won't budge.

I'm at wits end. Any ideas?

Sorry, I guess I should have mentioned. 08 Denali, auto climate. Using a vcx for diagnosis.

 

[Joseph Garcia]

@swathdiver

 

[swathdiver]

Hey folks. Another HVAC post. I haven't seen this exact same issue discussed before. As the weather warmed up this spring, I noticed my AC light was blinking, and wouldn't engage. Further investigation revealed I couldn't changed the mode at all. Stuck on heated defrost.

So far, I have changed out the recirc door actuator and mode door actuator. And the HVAC control unit. When I hook up the tech 2, it gives me B0423, B3779, B0228, and, B0413, all symptom 61. When I use the tech 2 to try and command them to change position, they won't budge, but all of the rear actuators work fine. When I do a recalibration, nothing changes. I was having the same issues with the old and new HVAC control unit.

I installed a new head unit over the winter, and thought maybe a messed up a connection to the control unit. Traced all wires back to the actuators and checked plugs...they seem fine. In I should mention that when I switched out the recirc actuator, it was out of range. But I have triple checked the new one, it's still within range, and won't budge.

I'm at wits end. Any ideas?

I forget exactly what the blinking light means, it has something to do with the compressor but I cannot remember or find it in my notes. My eyes are no good today too.

Addendum: OK, if the light flashes three times, it usually means you are trying to run recirc while in floor, defrost or defog mode and such is not allowed. It also flashes 3 times when the compressor is not available.

Are the replacement actuators ACDelco? What were the part numbers?

When you replaced the control head, did you program the new one to the vehicle?

Have you put a set of gauges (manifold) on the Hi and Lo ports and checked the pressures?

@91RS @gpracer1

 

[Apach 031]

Thanks for the response, swathdiver. I actually got it sorted out. I kept pulling the 10 amp fuse everytime I changed out a component, so I was confident it was good. When I replaced the recirc actuator (final part), I forgot to pull the fuse. I must have accidentally shorted the harness while it was disconnected. After banging my head for a day, I had a look at it, and sure enough, it was burnt. Very embarrassing. Everything is working great now!


Cheers