2001 chevy tahoe heater clicking noise

[thomasedwin]

The blend door actuator on this 2001 Tahoe was making the click, click, click noise so I took out the dash and replaced the unit. Before removing the unit I ran the heater to verify that this actuator was making the noise, I could hear and feel the unit making the clicking noise, It was difficult to replace because it's located on top of and behind the heater housing just about under the bottom of the wind shield and there's little room to get your hands and tools in there but I got the old actuator out and the new actuator back in and hooked up. I again ran the heater to check and there was no more clicking noise and I could see that the drive mechanism was opening an closing the blend door. I then put the dash and everything back in and then I started it up and let it run for a half hour or so and checked all the heating and cooling functions, everything worked correctly with no problems and no clicking noise. Then about three days later the clicking noise came back and it seemed louder than it was before, I don't know what else to do with it. The replacement actuator was purchased brand new from a reputable parts supply store and I'm 100% sure it's installed correctly. I even checked that the blend door was opening and closing and was not binding and there was no debris or anything blocking the blend door from moving. What could be causing this clicking or causing the new actuator to malfunction like this? I'm thinking of Taking it all back apart and fabricating a cam arm from the old actuator with a cable to manually open and close the blend door but I don't know if disconnecting the wiring will effect some other part of the heating system since I believe it's all controlled by the computer. How can I fix this???????

[MT-2500]

Originally Posted by thomasedwin

The blend door actuator on this 2001 Tahoe was making the click, click, click noise so I took out the dash and replaced the unit. Before removing the unit I ran the heater to verify that this actuator was making the noise, I could hear and feel the unit making the clicking noise, It was difficult to replace because it's located on top of and behind the heater housing just about under the bottom of the wind shield and there's little room to get your hands and tools in there but I got the old actuator out and the new actuator back in and hooked up. I again ran the heater to check and there was no more clicking noise and I could see that the drive mechanism was opening an closing the blend door. I then put the dash and everything back in and then I started it up and let it run for a half hour or so and checked all the heating and cooling functions, everything worked correctly with no problems and no clicking noise. Then about three days later the clicking noise came back and it seemed louder than it was before, I don't know what else to do with it. The replacement actuator was purchased brand new from a reputable parts supply store and I'm 100% sure it's installed correctly. I even checked that the blend door was opening and closing and was not binding and there was no debris or anything blocking the blend door from moving. What could be causing this clicking or causing the new actuator to malfunction like this? I'm thinking of Taking it all back apart and fabricating a cam arm from the old actuator with a cable to manually open and close the blend door but I don't know if disconnecting the wiring will effect some other part of the heating system since I believe it's all controlled by the computer. How can I fix this???????

Did you check the blend door for sticking or binding or broken?

[thomasedwin]

Originally Posted by MT-2500

Did you check the blend door for sticking or binding or broken?

that was the first thing I checked to make sure the blend door was not binding and there was nothing blocking it from moving and the new actuator was operating correctly before I put the dash back in.

[MT-2500]

Originally Posted by thomasedwin

that was the first thing I checked to make sure the blend door was not binding and there was nothing blocking it from moving and the new actuator was operating correctly before I put the dash back in.

If blend door is good and actuator is stripping gears then you are getting bad actuators.
Try a genuine GM parts actuator.

[j cAT]

Originally Posted by thomasedwin

The blend door actuator on this 2001 Tahoe was making the click, click, click noise so I took out the dash and replaced the unit. Before removing the unit I ran the heater to verify that this actuator was making the noise, I could hear and feel the unit making the clicking noise, It was difficult to replace because it's located on top of and behind the heater housing just about under the bottom of the wind shield and there's little room to get your hands and tools in there but I got the old actuator out and the new actuator back in and hooked up. I again ran the heater to check and there was no more clicking noise and I could see that the drive mechanism was opening an closing the blend door. I then put the dash and everything back in and then I started it up and let it run for a half hour or so and checked all the heating and cooling functions, everything worked correctly with no problems and no clicking noise. Then about three days later the clicking noise came back and it seemed louder than it was before, I don't know what else to do with it. The replacement actuator was purchased brand new from a reputable parts supply store and I'm 100% sure it's installed correctly. I even checked that the blend door was opening and closing and was not binding and there was no debris or anything blocking the blend door from moving. What could be causing this clicking or causing the new actuator to malfunction like this? I'm thinking of Taking it all back apart and fabricating a cam arm from the old actuator with a cable to manually open and close the blend door but I don't know if disconnecting the wiring will effect some other part of the heating system since I believe it's all controlled by the computer. How can I fix this???????

you did fix the problem // then it failed again. Take apart the whole mess and see if its broken as the original or some other factor.

post your results could help some members with this.

[thomasedwin]

Originally Posted by j cAT

you did fix the problem // then it failed again. Take apart the whole mess and see if its broken as the original or some other factor.

post your results could help some members with this.

I haven't taken it back apart yet but I believe It is not the actuator unit that is bad because I took apart the old unit and there was nothing wrong with it. I think there is a bad switch connection somewhere causing the vent door to continuously flip open and closed and the whole system is controlled by a computer.

[j cAT]

Originally Posted by thomasedwin

I haven't taken it back apart yet but I believe It is not the actuator unit that is bad because I took apart the old unit and there was nothing wrong with it. I think there is a bad switch connection somewhere causing the vent door to continuously flip open and closed and the whole system is controlled by a computer.

post the part number . also what is the function of this blend door. this the defrost air deflector ?

[thomasedwin]

Originally Posted by j cAT

post the part number . also what is the function of this blend door. this the defrost air deflector ?

The truck is across town in a storage building so I don't have access to the part number but the blend door is the one that is behind and above the glove box on the right hand passenger side on top of the heater housing near the fire wall just underneath the bottom of the windshield, This blend door determines if the blower air comes from the outside air or just recirculates the cabin air or a combination of both. When I had the actuator removed and turned on the blower this blend door would suck closed to one side and when I would manually move the door away from that side it had vacuum holding it shut but when I moved the door to about half way to the middle then vacuum would suck the door shut to the opposite side like the rutter on the tail of an airplane. It was very hard to aline the blend door so the new actuator drive would slip onto the shaft that operates the blend door but I got it on there and in the correct position. Once It was together I ran the heater and I could see that the blend door was moving it's full range from right to left and back again and there no clicking noise and everything else worked correctly. I put the dash board back it and checked everything again and it all worked as it should then a few days later it started clicking again louder that before. I took apart the old actuator and there was nothing wrong with it as in no broken gears or teeth and I could manually turn the mechanism and see there was no binding or obstruction and no dirt or anything stopping the position sensor from making contact, it still had the clean factory lubricant on it. When I get a chance I'm going to take it all apart and try again.

[j cAT]

the recirculation door is moving by an electric motor. the control would be from the HVAC control module. could be the door gear tooth is broken.

so your sure it is vacuum controlled you checked these vacuum lines . the vacuum goes to the part you installed or you installed this with a electrical connector?

[thomasedwin]

Originally Posted by j cAT

the recirculation door is moving by an electric motor. the control would be from the HVAC control module. could be the door gear tooth is broken.

so your sure it is vacuum controlled you checked these vacuum lines . the vacuum goes to the part you installed or you installed this with a electrical connector?

The movement of the blend door is controlled by a small DC motor inside the actuator unit with a series of small plastic gears and the final drive gear has a small electric contact arm attached to it that is in contact with a round flat metal surface somewhat like a volume control knob. I would say this electric contact sends a signal to the computer telling it what position the blend door is in. There are no vacuum lines that control the movement of the blend door, It only has a small plastic clip plug that connects 4 wires to the actuator unit, I believe 2 of these wires control the small DC motor and the other 2 wires are for the computer to sense the position of the blend door. When I was talking about the blend door slamming to one side or the other by vacuum it did this when the actuator unit was removed from the heater housing and there was nothing holding the blend door and it could move freely, when the blower was turned on the flow of air from the blower would cause the blend door to slam shut to either side of the vent openings. If the blend door was closer to the left side vent when the blower came on it would be sucked shut to that left side vent and if it was closer to the right side vent when the blower came on it would be sucked shut to the right side vent. When the actuator unit is installed it prevents the blend door from moving freely, that is the actuator controls the position. I know the small drive gears in the actuator are not broken because, not only is the unit brand new, I took apart the old unit and there was nothing wrong with it and it made the same noise as the new unit. The noise it's making is not that of grinding or slipping plastic gears, the noise is the blend door itself moving to one side and shutting then moving to the other side and shutting (flip flop, flip flop, flip flop) The actuator is working but it is continually going back and forth not moving to one position and staying there like it is supposed to. Something in the computer or a switch in the heater controls or the position signal from the actuator is causing the blend door to go from outside air and then back over to inside air resurculation again and again. I read in a blog somewhere that another guy had this same problem and a chevy dealership told him he needed a new computer. If that's the case it's not worth the cost of replacing the computer but the constant flip flop noise is very annoying. I'm thinking of pulling the dash back out and disconnecting the wires from the actuator and if everything else still works good just leave it disconnected.

[j cAT]

no vacuum controlling the door..blower was moving the door.

so now this may be the hvac control module needs to be reset. this can happen with a power loss.

with the key not in the ignition hvac controls to off, remove the radio fuse. after 15 min put the fuse back in. then turn ignition switch to on, ENGINE OFF , wait 2 min then start the vehicle see if it resets and the doors work properly.

[Fastandfurious_]

I just got a Monte Carlo with the same problem... But the dealer fixed it before i bought so not sure