Induction fan comes on ignitor wont ignite - Amana Gas Furnace 90% Afue 45000 Btu Variable Speed

That's a "mind of its own" condition that I've gained & lost customers over. When the unit first starts in heat, you mentioned the induced draft motor will start with no other reaction from the system, that should be the best time to locate the issue by using a volt meter. If you are getting 24 volts to MV/PV at the gas valve then you know all of the heating circuit has "proved", and that the gas valve is the problem. If not, the backtrac until you find 24v. Now if you are simply just changing parts until you find the problem, which we've all done, I believe you've changed all that you can. Check all wire connections. Its probably a loose, corroded, or damaged wire/cannon plug(the plastic plugs that multiple wires are connected), stopped up gas pilot orifice, or the gas valve its self. Hope this helps!

Check spark wire if OK bad module

If the thermostat isn't selected for "FAN" then the relay is stuck. In heat mode the thermostat opens the gas valve and starts the igniter and the induction motor. If the induction fan isn't running, the flame will stop.

CHECK VOLTAGE SUPPLY TO IGNITOR.

98? what engine?
the ignitor can be in 3 places on all cars.
1: fire wall. connects to 1 coil, or 2 coils(WS) or 4 COPS.
2: ECU
3 :inside the COPS.

the ignitor changes the induction (spark) coil.
and can be in any of 3 places.

i log in to alldata dot com, so can you (a USA example ONLY)
it has 2 (4pin( Igniters)
so obvious has wasted spark.
power pin, ground pin and 2 , pins to ECU.

it says, in the finder, ignition coils 1and2 with ignitor
in coil finder, and service, it states
remove throttle body to access coils

RTM
see coils, ? see wire they go to one place, the ignitor
follow the those wires, see igniters.

Sounds like either the flame sensor is not working.
The sequence for starting the furnace is:
1. extraction fan on
2. pressure sensor (for fan)
3. ignitor (spark or glow plug) comes on
4. gas valve opens up
5. ignition of flame
6. flame sensor (or temperature sensor)
7. plenum temp. sensor
8. main fan starts
It is most likely that the flame sensor is dirty or gone,
or (and I hope not), the module is gone and needs to
be replaced.

is the flame igniting and then cutting off? on a gas furnace, the induction fan motor(draft motor) should start first (if the furnace is so equipped), then the flame, then the blower. if you have an induction motor (flue gas exhaust mmotor) this may be your problem (the induction motor isn't starting), if your unit doesn't have one, have you checked to see that you have gas? finally, the capacitor on the blower motor may be causing the motor not to start.

Make sure all hoses to the pressure switch is free of moisture, Check the inducer fan for blockage, check air intake and exhaust pipe for blockage, remove air intake pipe from furnace if you have to. Check all condensate hoses for blockage, check the condensate pump if you have one, and jump out the pressure switch once the inducer motor comes up to speed to test it.

you need a service person to come out

couple things without more info is little hard,,,first not familliar with this paticular model but I believe it has a glo igniter,,which will be located next to the burners,,should be one or two scres holding it in,if this is not glowing than u need to pulll it out and look for a crack in it if its cracked u need to replace. If this is electronic ignition will have a metal spark ignition,,the glow ignitor will be ceramic by the way,,also if u pull out the glow ignitor do not touch the element with your hands while inspecting or replacing for the oil on your hands will cause it to fail sooner. sorry back to the metal spark ignition if it is not sparking than chances are u have a problem with the combustion fan motor shutting down the gas valve before it lights. I just posted on a goodman about the fan motor and the two types and how to fix. good luck.