LS XR4140HC heater vent knocking noise

[Drewmon]

Hi all,
I'm just checking to see if others are having a knocking sound from the ceiling of your cab when the tractor starts or switching the vents blower selection. I've been having this issue for a few months now. Sounds like it's trying to change the airflow flaps inside the heater, but its stuck.

Thank you

 

[atomchaser]

Were you able to resolve this problem? I have the same issue and will probably be taking a look at it this weekend.

 

[Drewmon]

I haven't had a chance to look at it yet. I did take a video of it happening which I'll upload to youtube and link here shortly. Were you able to do anything with it? I read that you have to remove the roof to access the system, still trying to figure out about doing that.

 

[atomchaser]

Mine does it when you startup the tractor and the airflow rotary switch is positioned at driver position (the human stick figure). If starting in defrost position, it doesn't make the noise. I didn't have time to investigate further. Raising the roof is simple and requires removing just 4 bolts (two in front and one on each side). It sounds to me like the gears on a positioning motor are stripped or missing a few teeth.

 

[SmurfOperator]

Mine does it when you startup the tractor and the airflow rotary switch is positioned at driver position (the human stick figure). If starting in defrost position, it doesn't make the noise. I didn't have time to investigate further. Raising the roof is simple and requires removing just 4 bolts (two in front and one on each side). It sounds to me like the gears on a positioning motor are stripped or missing a few teeth.

There are a couple electrically controlled actuators under the roof cowling. It is pretty normal for them to make a clicking noise when they do their power up cycle. If you are concerned about it or are having any functional degradation of your heat/ac system they are very easy to change out and aren't very expensive. The roof cowling can be opened by removing 4 12mm nuts. Have a second person manipulate the heat/ac controls while you watch the actuators and you should be able to easily spot what one is having trouble. They are held in place with a couple Philips head screws. If you have any mechanical experience the whole job should take less than 15 minutes.