1995 sierra hvac actuator problem

The truck is a 1995 gmc sierra 4 x 4 ext. cab . The floor heat works but not the defrost. I've read all the threads on this subject and started investigating. I found that the actuator that operates the flap that changes from floor/vent/defrost is not working. This actuator is above the gas peddle. I removed the actuator and turned the flap by hand and it works fine. I can get the defrost working so the mechanics of the flap are OK. No linkage problems etc. Now that I verified that the air inlet actuator is not working I connected it to the power wire from the heat mode actuator and it worked. So I think the actuator is OK. Several threads indicated that these systems run on a vacuum and the vacuum line might be damaged. I looked and found what looks like a vacumm line under the dash but I'm not sure and do not know how to test this. I've verified that the defrost control dial is not broken. Could the actual control panel on the dash be bad. Maybe a fuse?

The truck is a 1995 gmc sierra 4 x 4 ext. cab . The floor heat works but not the defrost. I've read all the threads on this subject and started investigating. I found that the actuator that operates the flap that changes from floor/vent/defrost is not working. This actuator is above the gas peddle. I removed the actuator and turned the flap by hand and it works fine. I can get the defrost working so the mechanics of the flap are OK. No linkage problems etc. Now that I verified that the air inlet actuator is not working I connected it to the power wire from the heat mode actuator and it worked. So I think the actuator is OK. Several threads indicated that these systems run on a vacuum and the vacuum line might be damaged. I looked and found what looks like a vacumm line under the dash but I'm not sure and do not know how to test this. I've verified that the defrost control dial is not broken. Could the actual control panel on the dash be bad. Maybe a fuse?

The actuator may still be bad. There is no vacuum used for the heater on your truck. In my case, the actuator was too worn out to move the linkage. If you remove the actuator, and then plug it in to the electrical connector, does it move when you change from defrost to floor, vent to floor?

If it moved when you supplied power to it, but it does not move when you change the position on the control panel, the control panel is probably bad.

//2000CAYukon

The actuator may still be bad. There is no vacuum used for the heater on your truck. In my case, the actuator was too worn out to move the linkage. If you remove the actuator, and then plug it in to the electrical connector, does it move when you change from defrost to floor, vent to floor?



If it moved when you supplied power to it, but it does not move when you change the position on the control panel, the control panel is probably bad.

//2000CAYukon

No it will not move and I know the actuator works. How strong I'm not sure but moves good. I'm thinking the control panel too. Thanks for the quick response. My first time on the site. I'ts great.

No it will not move and I know the actuator works. How strong I'm not sure but moves good. I'm thinking the control panel too. Thanks for the quick response. My first time on the site. I'ts great.
Hi Guys & Gals. Thanks for the help. It was the control panel. Bought one for $203.00 took 45 minutes to install and 30 minutes to get the actuator orientated correctly. At least now I know how to reemove the dash, stereo system etc. The hardest thing was figuring out how to remove the stereo and the dash pieces. If I can figure it out anybody can. Well almost everybody.