Inducer Assembly Replacement, A Step By Step Guide

That's right, with our inducer assembly replacement guide, you can diagnose and replace it if necessary. This would normally cost over $300 to have a dealer supply the part and replace it!


In order to know what is wrong, we must first know about the proper operation.

Normal Operation

The inducer assembly is a small fan that pulls air through the furnace heat exchanger and sends it to the outside through a vent pipe. In furnaces with an afue of 80-90% they are usually made of metal. In furnaces with an afue of 90% or more, they are usually made of plastic.

The inducer establishes a draft through the furnace and is sometimes referred to as a draft inducer. The motor is powered with 120vac from the furnace control board. During a normal call for heat, the control board will supply power to the inducer.

The inducer is connected to a pressure switch by a rubber hose. When the inducer starts the pressure switch is closed by the suction of the fan. The pressure switch has another hose that connects to the outlet of the fan. If the vent pipe is plugged with something, the pressure from the fan will cause the pressure switch to open.

After the pressure switch closes the furnace control will continue with the normal heat cycle.

Finding the problem

You should verify the inducer assembly is bad prior to replacement.

If the inducer motor starts when required but the furnace does not continue with the ignition sequence, the problem could either be the vent pipe(s) clogged or condensate in the inducer assembly.

Condensate can back up into the inducer assembly, on a furnace with afue of 90% or more, if the furnace's condensate trap gets clogged.

If the inducer motor does not start when required, you should feel the motor to see if it is hot. If the motor is hot, it should be replaced.

If the inducer is not hot, you should check to see if power is being supplied to the motor. If there is no power to the motor, ensure the thermostat is calling for the furnace to come on. If it is, then the control board should be replaced.

Inducer Assembly Replacement Procedure

Begin your inducer assembly replacement, by ensuring the power is off to the furnace and the furnace is cool. Then, you should mark the hose(s) and write down where they connect to on the inducer.

Then, you should mark the wires and write down where they connect to. Some inducers will have plug and socket connectors while others do not. Most inducers, on 90% afue or more furnaces, also have a small limit control mounted on the housing.

Next, the vent pipe should be disconnected. Then the condensate drain tube, on 90% or more units, should be disconnected.

Then, the inducer assembly mounting screws can be removed. Finally, the assembly can be removed from the furnace.

Continue your inducer assembly replacement by mounting the new unit in the furnace. On 80-90% afue units, high temperature silicone or a high temp gasket is used to seal it.


On 90%+ afue units, there is usually a rubber gasket.

Then you should reconnect the wires, pressure switch hoses, and the condensate drain tube (on 90%+ units). Then reconnect the vent pipe.

You should complete your inducer assembly replacement by restoring power to the furnace. Observe a complete heating cycle to verify proper operation.