New Issue with Hydroflame Furnace 8531-III

[RandyJ55]

I was proceeding to start up the furnace at the rv my brother stays at which I own. It is a Sunline Solaris Model T-2970 made in 1995. Last year the furnace ran fine all winter. This year I had to replace the motor as it turned very hard. I also tested the DSI board which tested fine. Lastly, I purchased a new Dinosaur Electronics TDR relay. The furnace clicks on when prompted by the thermostat calling for heat and the blower kicks on with a good sail switch and the ignition lights for ten seconds in a series of 3 times and then the furnace kicks off. I need to see if I could get any input or help in where to look next. I've tested the connections and the continuity for the wires where I can access both endpoints and the wires tested good. I'm not sure what to do or where to look next. I have already blown out the exhaust chimney with the end piece to the outside both assembled and disassembled to make sure there are no obstructions. I'm open to all suggestions or ideas that will get this furnace operational before the cold sets in. So far, all the suggestions that I have received through this forum have been tried and were successful in getting the furnace going every time I ran into an issue. Thank you