PetesPonies Posted September 16, 2017 Author Share Posted September 16, 2017 The selector door is what the door that changes where the air goes is called. You are selecting the position. Not sure I'm getting through. Don't mean to insult you, but I don't want you fixing things that aren't broken. There is more than one door in the system. There is NO single "selector" door. Three separate vacuum-operated doors work in series to route air as commanded. A fourth door (cable-operated) controls hot or cold, but let's skip that for now. Here's how air flows. Go to that first illustration at the hinge repair link for more details. Air is drawn into the plenum by the fan. The first vacuum-operated door (recirc) controls whether air comes from outside or inside. In the event of a loss of vacuum, this door actuator is spring-loaded to the outside (fresh air) position. The next step is the temperature blend door. This is the cable-operated door. For maximum heat, all air goes through the heater core. For no heat, all air bypasses the core. The door can be positioned anywhere in the middle for heat control. Next step is the panel vent door. With vacuum present at the actuator, ALL air flows to the four registers on the face of the dash, AND the passage to the defrost and floor nozzles is blocked. With no vacuum at this actuator, it's spring-loaded to send all air downstream to the defrost or floor nozzles, and none to the panel vents. Last step is the floor/defrost door. Remember, the panel vent door actuator must be relaxed for any air to reach this last door. The floor/defrost door simply routes air up to the defrost nozzles or down to the floor. This actuator also has a mid position to route air to both the defrost and floor nozzles. For a loss of vacuum, this door is spring-loaded to the defrost position. You mentioned having only defrost available. That would point to a complete lack of vacuum, as previously suggested. Start there, and make sure you have engine vacuum reaching the dash selector switch. After that, check the vacuum outputs from the selector switch to the individual actuators. Just don't go looking for that one mythical "selector" door, cuz there ain't any such thing. Hope this helps. More details here: EVTM Ex Auto teacher here, I do get it. You didn't get my over simplified response for what a selector door is. Whether this vehicle has that simple of a system is irrelevant to what the term means. I'm ignorant of these trucks, and why I'm asking. I restore older cars and trucks, this is my first into these Bullnoses. Pete's Ponies Mustang RUSToration & Performance Link to comment Share on other sites More sharing options...
85lebaront2 Posted September 16, 2017 Share Posted September 16, 2017 Ex Auto teacher here, I do get it. You didn't get my over simplified response for what a selector door is. Whether this vehicle has that simple of a system is irrelevant to what the term means. I'm ignorant of these trucks, and why I'm asking. I restore older cars and trucks, this is my first into these Bullnoses. Pete's Ponies Mustang RUSToration & Performance FWIW, Our government decreed starting in 1968 that any non-mechanical system (vacuum or electric control) is supposed to default to defrost if the controls, in this case vacuum, aren't working, most likely place to look is the fresh air/recirc vacuum actuator in the right rear corner of the engine compartment, the two lines there, one black and one white, get brittle and crack. Link to comment Share on other sites More sharing options...
kr98664 Posted September 16, 2017 Share Posted September 16, 2017 most likely place to look is the fresh air/recirc vacuum actuator in the right rear corner of the engine compartment, the two lines there, one black and one white, get brittle and crack. Good suggestion. A handheld vacuum pump (MityVac or similar) is great for troubleshooting. Use the EVTM and work your way through the system. Be aware most leaks, whether a line or actuator, can take out the entire system because vacuum can't build up. If you find a leak, play with the selector lever because that shuts off certain circuit branches in various positions. Karl Link to comment Share on other sites More sharing options...
PetesPonies Posted September 17, 2017 Author Share Posted September 17, 2017 most likely place to look is the fresh air/recirc vacuum actuator in the right rear corner of the engine compartment, the two lines there, one black and one white, get brittle and crack. Good suggestion. A handheld vacuum pump (MityVac or similar) is great for troubleshooting. Use the EVTM and work your way through the system. Be aware most leaks, whether a line or actuator, can take out the entire system because vacuum can't build up. If you find a leak, play with the selector lever because that shuts off certain circuit branches in various positions. Karl Yeah I was going to pull out my MityVac and see what I can find. I have so much work to do, customer work, a couple rental properties that have new renters , etc . . I haven't tried anything yet. Perhaps tomorrow or Monday. I did accomplish this today :) Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted September 17, 2017 Share Posted September 17, 2017 Yeah I was going to pull out my MityVac and see what I can find. I have so much work to do, customer work, a couple rental properties that have new renters , etc . . I haven't tried anything yet. Perhaps tomorrow or Monday. I did accomplish this today :) K2? Link to comment Share on other sites More sharing options...
PetesPonies Posted September 17, 2017 Author Share Posted September 17, 2017 K2? It's a customer's bike. I think, it is a '75. It's Planet Blue Metallic. Link to comment Share on other sites More sharing options...
Gary Lewis Posted September 17, 2017 Share Posted September 17, 2017 K2? Looks like the K2 I had. Only lots prettier. Link to comment Share on other sites More sharing options...
PetesPonies Posted September 17, 2017 Author Share Posted September 17, 2017 Looks like the K2 I had. Only lots prettier. The first blue available on a CB750 was 1975. On 9/17/2017 5:12 PM, Gary Lewis [via Bullnose Enthusiasts] wrote: -- Pete's PoniesMustang RUSToration & Performance Link to comment Share on other sites More sharing options...
ctubutis Posted September 17, 2017 Share Posted September 17, 2017 This forum software is enough to drive a guy crazy. No arguments from me. ;) With any luck, stuff will be getting better (and maybe worse, depending on your point of view) over time. Link to comment Share on other sites More sharing options...
broboyle Posted February 11, 2019 Share Posted February 11, 2019 The selector door is what the door that changes where the air goes is called. You are selecting the position. Not sure I'm getting through. Don't mean to insult you, but I don't want you fixing things that aren't broken. There is more than one door in the system. There is NO single "selector" door. Three separate vacuum-operated doors work in series to route air as commanded. A fourth door (cable-operated) controls hot or cold, but let's skip that for now. Here's how air flows. Go to that first illustration at the hinge repair link for more details. Air is drawn into the plenum by the fan. The first vacuum-operated door (recirc) controls whether air comes from outside or inside. In the event of a loss of vacuum, this door actuator is spring-loaded to the outside (fresh air) position. The next step is the temperature blend door. This is the cable-operated door. For maximum heat, all air goes through the heater core. For no heat, all air bypasses the core. The door can be positioned anywhere in the middle for heat control. Next step is the panel vent door. With vacuum present at the actuator, ALL air flows to the four registers on the face of the dash, AND the passage to the defrost and floor nozzles is blocked. With no vacuum at this actuator, it's spring-loaded to send all air downstream to the defrost or floor nozzles, and none to the panel vents. Last step is the floor/defrost door. Remember, the panel vent door actuator must be relaxed for any air to reach this last door. The floor/defrost door simply routes air up to the defrost nozzles or down to the floor. This actuator also has a mid position to route air to both the defrost and floor nozzles. For a loss of vacuum, this door is spring-loaded to the defrost position. You mentioned having only defrost available. That would point to a complete lack of vacuum, as previously suggested. Start there, and make sure you have engine vacuum reaching the dash selector switch. After that, check the vacuum outputs from the selector switch to the individual actuators. Just don't go looking for that one mythical "selector" door, cuz there ain't any such thing. Hope this helps. More details here: EVTM I am having issues with my temperature control lever (top lever) where it gets stuck when moving the temperature from cold to warm (left to right). The lever gets stuck in the middle (shown in green in the attached photo). From the information in this thread, it appears this is a cable operated door. How can I troubleshoot this issue and what is the fix? Thank you! Michael Link to comment Share on other sites More sharing options...
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