Heater / blower only works on windows / 1997 K1500

[Thijmen]

Hello everybody,
Yesterday I picked up my 1997 K1500. Now it's got some issues, one of them being that the heater only blows air on the windows. When I set it to any other mode nothing changes and it keeps only blowing air through the window vents.
Also when I turn on the AC the button lights up, but as soon as I turn the left dial from 'off' to any other mode the light goes out and the AC doesn't work. Both temperature and fan speed do work without any issues.
Anyone else who had this issue and who can tell me if this is a bad heater control panel or something else?

 

[RawbDidIt]

Hello everybody,
Yesterday I picked up my 1997 K1500. Now it's got some issues, one of them being that the heater only blows air on the windows. When I set it to any other mode nothing changes and it keeps only blowing air through the window vents.
Also when I turn on the AC the button lights up, but as soon as I turn the left dial from 'off' to any other mode the light goes out and the AC doesn't work. Both temperature and fan speed do work without any issues.
Anyone else who had this issue and who can tell me if this is a bad heater control panel or something else?

Most likely a dead blend door actuator. The one you're looking for is under the dash, it's shaped like a home plate for lack of a better description, pointing towards the front of the vehicle. Should be able to see it without removing anything by looking under the dash towards the trans hump from the driver's side door at the very end of the heater duct. Test it by unplugging the harness and seeing if the part gets voltage when you change the setting if it does, plug it back in and see if it moves when you change the setting, if not, new actuator.

Sent from my SM-G965U using Tapatalk

 

[Thijmen]

Most likely a dead blend door actuator. The one you're looking for is under the dash, it's shaped like a home plate for lack of a better description, pointing towards the front of the vehicle. Should be able to see it without removing anything by looking under the dash towards the trans hump from the driver's side door at the very end of the heater duct. Test it by unplugging the harness and seeing if the part gets voltage when you change the setting if it does, plug it back in and see if it moves when you change the setting, if not, new actuator.

Sent from my SM-G965U using Tapatalk

Just tried this! It gets 12v on the right pin and between 7 and 8.5v on the middle pin depending where I change the setting to. It doesn't move at all when I plug it back in. I guess I'll be looking for a new actuator

 

[RawbDidIt]

Just tried this! It gets 12v on the right pin and between 7 and 8.5v on the middle pin depending where I change the setting to. It doesn't move at all when I plug it back in. I guess I'll be looking for a new actuator

Awesome, sounds like you've got it sorted.

Sent from my SM-G965U using Tapatalk

 

[WillB]

Not to high jack this thread buuuttttttt, I'm looking at the same issue on my 99 K3500. What is the difference between the 3 terminal and the 4 terminal? The parts store offers both.