FURNACE REMOVAL
I guess that I have not stayed current on Suburban furnaces since I changed to an Atwood. I was just looking through a couple of manuals and see that they have made some good changes! In any case, you might be wise to visit
http://bryantrv.com/docs.html and down-load the service information on your furnace. I think that you would find it to be pretty helpful.
I think that the "sail switch" is probably what you are thinking of. It's failure to close when the blower starts is the most common reason for the problem that you have. Of course, there can be several different reasons that might cause that. By far the most common is dirt or some other obstruction in the air flow path. That same motor turns two blowers, one to move combustion air and the other moves the inside air through the heat exchanger. The sail switch is a safety device to prevent the gas flow when there is not enough air movement through the furnace. There is a good chance that if you bench test it you can check and determine if the sail switch is closing or not, without connecting the propane to allow it to burn. Very often a complete cleaning of all parts of the furnace will make that problem go away. Just use jumpers to supply the blower motor with 12V power and put your meter across the sail switch to see if it closes.
I would assume that you realize that if your furnace gets any less than 11V it may not close the sail switch and at 10.5V it won't close. The reason I ask is to be sure that you have checked the power to the furnace before you remove it.