Can I add an A/C unit to my Miller Furnace model M1mB 090a bw?

If it burns out the transformer you have a short on the low voltage line somewhere, use an ohm meter to find the short, start by unhooking the thermostat wire

Check to see if fan is running .If not check capicator

First it will need a clean /service . Sounds like the pilot is blocked this needs cleaning as does the heater . It needs a service and a new filter . .

did you check the hose from the inducer to the pressure switch? HAVE you unplugged the unit from the wall outlet to reset the board? DO you have a voltmeter? If you do you can run voltage across the switch and if you get 24 volts you are open.

CHECK FLUE FOR OBSTUCTIONS AS WELL AS COMBUSTION AIR INTAKE FIRST. THEN CHECK TO SEE IF THE FURNACE DRAIN IS OPEN AND NOT CLOGGED [ONLY IF YOUR FURNACE IS A CONDENSATING HIGH EFFICIENCY MODEL, typically the flue pipe will be 2 or 3 inch pvc pipe] over the years more often than not, it is an obstruction or poor drainage which will not prove the pressure switch to allow the burner to ignite. in rare cases the furnace control board could be bad as well.TRY DISCONNECTING FLUE AND COMB. AIR AT FURNACE JUST TO SEE IF FURNACE WILL IGNITE. HOPE THIS HELPS!!!!!!

Hello, first turn off power to the Furnace, then remove igniter from bracket and unplug molex connector. Then take the igniter to a Hvac supply store and get new one, reinstall it into bracket plug into molex connector and turn furnace back on.

The combustion blower is easy to replace. You may be able to prolong the life of the motor by applying lubrication to the shaft bearings. If the motor is too far gone then replacing it is the only option. Just remove the screws that mount the blower case to the heater, disconnect the wires and reverse the steps to install a new motor.

Check your furnace filter any Limit fault code usually relates to airflow...Not enough...causes the furnace to run too hot and shut off....the furnace can be too big for your house if its new...the ductwork can be too small , also make sure your return air vents are clean and unobstructed . Your furnace can be running too long a cycle ....also if you have central air conditioning the coil for the AC in the Furnace can be dirty...restricting airflow...if all this seems ok you can usually increase the fan speed or try tunning the fan in the "On" position on your thermostat this will promote better circulation