When adjusting the AC to 'blue' cold side on the 1994 land cruiser I could hear a ticking sound coming from the servo motor--about an inch from max cold temp. I opened up the dash to inspect the Servo-mix motor and found that I had about 3 teeth that were rounded off and chipped on the main plastic gear. Already planning for the worse, I bought an additional motor from ebay to replace it with; however, when inspecting the main gear, I noticed that there were 180 degree offset holes for the copper contact arms.
With a small screw driver, I pulled up on the contact arms (not bending them) and reset them on the gear (you can see the old shadow marks from the original location on the photos.
Because this gear only rotates about 90 degrees, the majority of teeth are never used. I was luckily to find the 180 degree offset to get some more life out of this 32 year old motor. The reset kept the original worn area out of the equation, and I was able to work new teeth on the old gear.
The most important thing I noticed was the blend valve cable that operates the heater valve inside the engine bay was not as smooth as it could be. I added a little tri-flow oil inside the cable housing to make it easier to move. This little servo motor and gear has a lot of torque and it probably is the most used motor in the system. It operates the largest flap-- from AC to Heater air, but additionally moves the cable that operates the heater valve. All of that movement with a small 12v motor and a small 2" plastic gear.
Best advice is to keep the heater valve, cable, and linkage as clean and lubed to ease the strain on the plastic motor gears.
With a small screw driver, I pulled up on the contact arms (not bending them) and reset them on the gear (you can see the old shadow marks from the original location on the photos.
Because this gear only rotates about 90 degrees, the majority of teeth are never used. I was luckily to find the 180 degree offset to get some more life out of this 32 year old motor. The reset kept the original worn area out of the equation, and I was able to work new teeth on the old gear.
The most important thing I noticed was the blend valve cable that operates the heater valve inside the engine bay was not as smooth as it could be. I added a little tri-flow oil inside the cable housing to make it easier to move. This little servo motor and gear has a lot of torque and it probably is the most used motor in the system. It operates the largest flap-- from AC to Heater air, but additionally moves the cable that operates the heater valve. All of that movement with a small 12v motor and a small 2" plastic gear.
Best advice is to keep the heater valve, cable, and linkage as clean and lubed to ease the strain on the plastic motor gears.