sail switch in Suburban furnace

Thanks for all the info. The furnace does have an outside access door, so I'll give that a shot and replace both the hi-limit switch as well.

I'm assuming that the great info above also applies to model sf35?

(My sf35 doesn't want to start. So far I've just confirmed t stat is ok. Mine is in such a tight spot I need couple extra elbows in each arm to work on it. Hopefully same layout as sf30)

Boon Docker wrote:
Doug, have you replaced one without removing the furnace?
The reason I ask is because the sail switch should be at the back of the furnace. Which would be hard to access without removing the unit.

The SF 30 is installed from the outside with an outside access door and the Sail Switch is right in front of you. The Hi Limit switch is also accessible without pulling the furnace. ALL the SF 30's I have worked on have an inside louvered grate cover on the inside cabinet where the furnace is located. You remove the OEM cabinet cover and the back of the furnace has a metal plate with 2 screws. You remove those 2 screws and the rear metal furnace cover comes OFF and the Hi limit is also staring you in the face. As I stated, the most common cause of Ignition failure on an SF-30 is the Hi Limit switch. Doug

It all depends on the installation. If you have an outside access door to work on the furnace, you can remove the fan cover and replace the sail switch. If your furnace is installed from inside the RV and only the intake and exhaust pipes are visible from the outside of the RV, you will need to pull the furnace to get to the sail switch.

Doug, have you replaced one without removing the furnace?
The reason I ask is because the sail switch should be at the back of the furnace. Which would be hard to access without removing the unit.

The sail switch can be replaced without pulling the furnace. The most common part failure on the SF 30 is the hi limit switch. Doug

It is possible to jumper it out to see if it is faulty. Try that first.

Dealer replaced one on a previous trailer we had...he pulled the furnace (and put a gouge in the flooring.....:M)

Are you positive it is bad?