Prolonging the life of the blend door actuator?

[Whosondephone]

Last night I hear a ticking when the thermostat temperature is below ambient. It sounds like it's coming directly from where the blend door actuator sits. It seems to be working for the moment.

Over the past 4 years I've almost completely overhauled the HVAC system. Is it normal to have to replace the blend door actuator every 2 years?

When I installed the new one, before reassembling the dash, I monitored the blend door actuator in action. I noticed that when the thermostat was set to 65 the blend door appeared closed. When setting to 60, the next lowest value, It looked like the actuator was putting more pressure on the blend door but not necessarily closing it more.

Am I using the HVAC wrong? The failed actuator had striped teeth off the gears. Before I was setting the temperature at a reasonable setting somewhere around 70 or so. After replacing I thought maybe if I used more extreme settings it wouldn't be constantly wiggling back and forth and wear out the gears. Perhapse it is the most extreme setting that are putting varying pressure on a single tooth. In the winter I would ajust the temperature so that the blend door was fully open. Run the blower on the lowest setting. And open the window if it gets too hot. That's probably what melted the blower motor resistor. The blend door actuator probably was cooking up there too.

Should I try to get a new actuator from the dealer? Should I get another cheap one from rock auto or perhapse try the auto parts stores? Do you think I would be ok if I operate it in the middle? That's the way I assume it is intended to be used. I'm considering modifying one bypassing the servo. Operate it off a simple on off on Last night I hear a ticking when the thermostat temperature is below ambient. It sounds like it's coming directly from where the blend door actuator sits. It seems to be working for the moment.

Over the past 4 years I've almost completely overhauled the HVAC system. Is it normal to have to replace the blend door actuator every 2 years?

When I installed the new one, before reassembling the dash, I monitored the blend door actuator in action. I noticed that when the thermostat was set to 65 the blend door appeared closed. When setting to 60, the next lowest value, It looked like the actuator was putting more pressure on the blend door but not necessarily closing it more.

Am I using the HVAC wrong? The failed actuator had striped teeth off the gears. Before I was setting the temperature at a reasonable setting somewhere around 70 or so. After replacing I thought maybe if I used more extreme settings it wouldn't be constantly wiggling back and forth and wear out the gears. Perhapse it is the most extreme setting that are putting varying pressure on a single tooth. In the winter I would ajust the temperature so that the blend door was fully open. Run the blower on the lowest setting. And open the window if it gets too hot. That's probably what melted the blower motor resistor. The blend door actuator probably was cooking up there too.

Should I try to get a new actuator from the dealer? Should I get another cheap one from rock auto or perhapse try the auto parts stores? Do you think I would be ok if I operate it in the middle? That's the way I assume it is intended to be used. I'm considering modifying one bypassing the servo. Operate it off a simple on off on switch. Or drilling a hole in the dash in order to reach with my hand. Does anyone have any techniques for prolonging the life of the blend door Actuator?

I was so close to having air conditioning in my car for the first time ever. Darn!

[gadget73]

these things are stupidly unreliable and it always seems to be stripped gears. I really wonder if its just a design flaw, the blend door itself maybe cannot move as far as the actuator does so its just grinding itself to bits. Not sure if its really possible to do, but what would fix that is a spring coupling between the two that would allow for over-travel in both directions without shredding anything. The stuff in my Continental works that way, it has a spring in there so the actuators can travel further than the doors and it just compresses the spring as needed. To my knowledge they are original from 1984, so it seems to work. The insides are just crappy little plastic gears. I had them apart to replace the petrified grease but the gears are fine.


Even if you set it in the middle, the system will run the door full cold or full hot to start in order to bring the cabin to temperature, and it will pull back from end of travel as it approaches set temperature.

[sly]

It is the plastic gears. It's a designed failure point. The only reason for this is to prevent breaking the blend door shaft. Even though that does still happen occasionally. I've replaced the rear blend door actuator in the Expedition twice now. The second one has lasted 5 years though, so there's that. I think it was the Dorman one.