I'm having the same problem with my 1991 Toyota Itasca IT 321 RV spirit. I can't get the Suburban heater out. I got the 2 screws outside on the exhaust out completely, two screws inside on floor are removed, gas line is disconnected.
update: I finally got the furnace out, repaired it and it's working beautifully. To get it out I needed to remove on the outside the exhaust flange and tube that goes into my rv which is only about a foot long.
Then I realized also the cabinet was pressing down (where the drawers slide in & out) on the top of the furnace keeping it tightly bound even though the 2 screws had been removed.(holding the furn. in place) So once I tapped the cabinet crossmember upward away from the furnace relieving the pressure I was able to pull the furnace out.
I found the sail switch to be the problem because it wasn't sensitive enough to be activated when the voltage dropped a little bit on the battery(fan not generating enough wind), before it would not work properly if the voltage was down below 12 volts. Now it works when the voltage drops down to even 10.5 volts.
I also noticed the fan would bind when I turned it by hand for about maybe one quarter of its full turn and it was because they had tightened one of the screws that mounted the fan in the housing too much at the time it was manufactured.....so I've always had this challenge now going on 25 plus years. This unit now works better than it ever did once I relieved the screw pressure so that the blade of the fan can turn freely (meaning the fan can turn faster helping to actuate the sail switch.)
They wanted to charge me $100 plus an hour to troubleshoot this furnace and I thought it was crazy since it was intermittent and would have taken countless hours of troubleshooting..... I would have gone broke....the guy would have wound up owning my RV by the time he figured it out.?
