BCM Community
Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: Jim Blackwood on May 01, 2020, 01:29:01 PM
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So this can be a problem area. In the D series they handled it both with a manual cable and with an electro-mechanical setup that had a controller in the dash. Sometimes the cable goes bad, even on the fancy rig. That happened to mine, and apparently the solution was to tape off the vent holes, whack off the cable, and remove the actuator which was above and behind the spare tire. The most sensible fix seems to be a new manual cable, which is reasonable for how heavy duty it is, but installing it, or more to the point getting the old one out is the challenge as the end of the sheath is in a pretty inaccessible spot.
Well I've done it, and once you know how it isn't quite as bad as it looks at first. To be sure, you have to pull the spare, the defroster/AC panel and lay on your back working overhead, but once you have the 90 degree flexible coupler (fresh air duct) removed the job becomes a lot clearer. There is a clamp with two 10-32 phillips head screws that holds the sheath, and the cable makes an immediate 90 degree bend. On mine the screws were rusty. I got the bottom one out but the head on the top one stripped, however I was able to spring the bracket enough to get the sheath to slip out.
Putting in the new cable should go smoothly enough. I'll position the handle right next to the other one that controls the heat. Getting the duct back in will be a pain of course but then I can button up the front area. In retrospect the fear and loathing of anticipation and the unknown were much worse than the actual job. Figuring out how to do it was the key, and now all y'all know that too.
Jim
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What condition did you find the air flow damper bits? Robust? Sealing? Were both the coach hvac and driver's fresh air dampers present?
The cables on the driver's controls were a problem from the beginning. The electro-pneumatic one on the coach hvac is also found in freightliner highway tractors, where they sealed tight as a drum. Never could tell what they were doing in the bus...
Control of fresh air is important for health, defrost and ac performance. Too many conversions have none.
Happy coaching!
Buswarrior
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The damper itself is fine. There is one small tear in the seal but it doesn't affect sealing and the hinge operates freely. I will oil it though. As far as I can tell, maybe someone tried to force the damper closed and bent the wire. After that it never worked right again.
I believe the coach damper works correctly but I will check that before the spare tire goes back in. I think I checked it once already. With the new cable installed the dash damper should work correctly and make a perfect seal.
Jim