We've got twenty more than that here... Do you wnat me to fax you some of them?![]()

I think you have a working plan. Do you plan to order this stuff and give it a try? I do, but it may be a while before I can get to another project.View attachment 82578
OK, here is my updated schematic...I think this will do it unless anyone has additional input. seems like it should be nice and clean.
the one box should read:
Air pressure switch has NO and NC connections… NC would always run the fan in reverse and when pressure is up from driving it will run normal . It can be set fairly light it appears.
I still think the simplest solution is a momentary contact switch, It will only run in reverse whiIe your thumb is on the button that way.
You are correct, but then why fix the problem with a 2 dollar switch and a ten minute fix with when you can do it 200 dollars of electronics and weeks of development?
In stop and go traffic when the fan would be running in thumb switch reverse. The moment you lifted your thumb the fan would continue to spin In the reversed direction(for at least a second or two). So with your thumb now lifted and the fan continueing to spin in reverse. It would be be hit with a flow of juice to spin the opposite direction. Seems to me that may work once or twice but at some point somethings going to fail.
Sometimes it costs a little more to get it right. Two hundred seems excessive. Unless, it was a BRP fix. Then a person could expect it to be redicuosly expensive.
I think you have a working plan. Do you plan to order this stuff and give it a try? I do, but it may be a while before I can get to another project.
In stop and go traffic when the fan would be running in thumb switch reverse. The moment you lifted your thumb the fan would continue to spin In the reversed direction(for at least a second or two). So with your thumb now lifted and the fan continueing to spin in reverse. It would be be hit with a flow of juice to spin the opposite direction. Seems to me that may work once or twice but at some point somethings going to fail.
Sometimes it costs a little more to get it right. Two hundred seems excessive. Unless, it was a BRP fix. Then a person could expect it to be redicuosly expensive.
how a bout a rocker switch with off in the middle. flip it off for a few seconds then back on in the other direction. Or maybe just a solid state time delay to give the fan time to stop before it reverses direction.





.... due to the Chinese New Year celebrations, where we pay respect to both the living and the dead, one's usually quite busy during this period.... so far my system is up and running well without the air flow switch, just need to remember to switch back to normal fan direction mode when heading out of town.... the components needed for my system is just one DPDT relay (for reversing fan direction), one SPDT ON-OFF-ON rocker switch (for override-normal-reverse mode respectively), one SPDT relay (for a key switched power supply), one 30A fuse holder (for override continuous mode) and also appropriate grade of wirings and wire connectors.... and also of course the air flow switch to be fitted later, I have problems getting the switch, so most probably I will be making one using a micro switch.... I have also observed the fan changing directions immediately with no visible strain nor abnormal noise but I may also install a delay timer for longevity of the fan.... above are some pictures...View attachment 82586
Well, I only found 1 automotive grade delay on timer... several non-automotive grade... Adds about $60 to the project, but it should adequately protect the fan.
Parts List:
Cole Hersee Relay 24452
Cole Hersee Cover 97297
1 complete set of Delphi connectors (1205792 & 3 and pins and seals)
Wolsentech TDR-P (need 2)
Cleveland Controls NS2-0000-01 air pressure switch
Cleveland Controls Universal Air Flow Sample Probe & Tubing Kit 60681-010
If anyone comes across a less expensive automotive grade delay on relay, please post a link...these listed are about $30 each...