102317-01 – DOOR INTERLOCK SWITCH (LENNOX, 51W15)

Lennox door interlock switch, catalog number 51W15, described by Lennox as a single pole normally open interlock switch. It is mounted at the blower access panel so that removing the door opens the circuit and de-energizes the unit, and the furnace will not run with the panel off if the switch has failed open.

Specifications published by the manufacturer. Source: manufacturer documentation.

Specs

• BrandLennox
• Catalog Number51W15
• Model/Part Number102317-01
• TypeDoor Interlock Switch
• Contact ConfigurationSingle pole, normally open (SPNO)
• Amperage16 A at 125/250 VAC
• Gross Weight0.15 lb
• UPC66255140039

Cross-reference numbers

This part replaces the following OEM and aftermarket numbers:

• 51W15
• 25J13
• 25J1301
• 51W1501
• 70L63
• 11W46
• 70L6301

Not sure if your number matches? Call (214) 340-9421 or bring the old part in — bench-testing is free.

What does the blower door switch do?

It is an interlock. With the blower door off, the switch opens and drops power to the blower, and on a lot of furnaces to the control board as well. Most are line voltage rated. It keeps hands out of a spinning blower wheel, and it keeps the blower from running with the burner compartment open where it could pull combustion products into the return.

My furnace quit the second I closed the panel. Where do I look?

At the switch and at the door itself. The panel has to seat far enough to push the plunger in, so check for a bent plunger, a door hung up on a screw or on wiring, a bracket knocked out of position, or a switch simply worn out from being cycled every time somebody changed a filter. If holding the plunger in by hand brings the furnace back, you found it.

Is it OK to tape the plunger down?

Common, and still a bad idea. Hold it in with your finger while you are watching the burners light, then let it go when you are done. Leaving it defeated means the next person to open that panel does it on a running blower, and it hides a door that is not seating.

Are door switches universal?

Close, not quite. Match the action (plunger or lever), whether it rests open or closed, the voltage rating, and the mounting hole spacing. Bring the old one in and we will lay it next to what we stock.