Mech Posted July 6 Report Share Posted July 6 When running the A/C, The highest fan setting seems a little weak. When i put the fan on the feet setting, it blows much harder, when I put it back to face/body setting it blows hard for a few seconds, then goes back down to half speed again. It does this consistently when switching back and forth from face to feet. What is causing this? Link to comment Share on other sites More sharing options...
TexasQuest Posted July 7 Report Share Posted July 7 Could be a blockage or misalignment in the air ducts possibly. Link to comment Share on other sites More sharing options...
Mech Posted July 9 Author Report Share Posted July 9 figured out the issue, but now i have another issue thats related Link to comment Share on other sites More sharing options...
tux Posted July 9 Report Share Posted July 9 I kind of wish they used solenoids or stepper motors for this stuff Link to comment Share on other sites More sharing options...
psu_Crash Posted July 10 Report Share Posted July 10 On 7/9/2024 at 11:04 AM, tux said: I kind of wish they used solenoids or stepper motors for this stuff Yeah ... the vacuum actuated everything was unfortunately kind of standard for the time though. With a little ingenuity and a LOT of time you could definitely swap in solenoids. Probably not worth the amount of time it would take to spec it all out, fabricate, then trial and error until it is working though. Link to comment Share on other sites More sharing options...
tux Posted July 11 Report Share Posted July 11 I dunno, it might be pretty simple. Thinking back I remember a post somewhere talking about hot to either fix or replace the actuators from McMasterCarr parts. Doesn't help your valve problem though Link to comment Share on other sites More sharing options...
mikec Posted August 31 Report Share Posted August 31 I can't see the video nor any pictures - none of the links work now. But a common issue with the vacuum actuators is the face/foot actuator getting cracks/splits/tears in the rubber bellows part. That becomes a big vacuum leak and the actuator fails to fully move in that direction. A temp fix is to slather epoxy over the split area, sealing it. But soon another part of the bellows will split/tear... Go to a hobby store that sells radio controlled cars and boats. They often have similar looking rubber bellows for the boat drive and steering mechanisms. Find one that is similar in diameter at each end and use that to replace the factory bellows. Cut the factory bellows part in the ribbed section - leaving the ends (where it clamps the actuator shaft and the face of the actuator body) intact. That'll give the R/C bellows something to grip/attach to. A little epoxy will seal the new R/C bellows to the remnants of the original bellows ends. Other folks have discovered a bellows inside the door is similar too... a junkyard run may be in order. As for the fan motor itself... the climate control computer uses a Darlington pair "power transistor" (a physically large transistor that can handle the amps of the motor and has a high gain) to adjust the fan speeds when the system is on AUTO mode. In manual mode, the system uses that same transistor for low fan speeds. For manual and AUTO modes, when MAX fan speed is selected a relay bypasses the transistor to supply full battery voltage directly to the motor. That relay is one of the relays attached to the evaporator box underneath the dash. Connector B-73 with black, blue+black, blue+yellow, and a red wire on the wiring harness side of the connector. Another issue: the "brushes" inside the motor wear down. Motor brushes are just rectangular shaped carbon bricks; a wire is attached to one end and the other end rubs against the rotating armature of the motor, wearing into an arc=shaped end. That arc-shaped end gets shorter and shorter as the brush wears from use. The guts of the motor will be full of carbon dust when this happens. It is a bit of a dirty pain to replace the brushes but it can be done. Take one old brush to a motor repair shop, a fully stocked ACE hardware store, or some other place that sells replacement brushes (they'll be in those metal cases just like the screw assortments) and find a brush with the same cross section size and at least as much wire length. The new brush should be much longer, about half an inch long if I remember correctly. It's been ages since I had a StarQuest interior fan motor apart... and I've had many other motors apart since then. mike c. 2 Link to comment Share on other sites More sharing options...
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