Fireplace extrodinair 36zc fan/temp control

I have a Model 36zc Fireplace extrodinair fireplace which has a rheostat for fan speed and a snap disc limit switch mounted in the chamber wall where the air heats. My issue is the AC fan motor is supposed to come on when the limit sees temp rise approx 110 deg or more, not really sure its setting and when it drops possibly to 90 deg it supposed to turn the fan off. I spoke to the manufacture about its inconstancy of operation and they seem to blame the wood is not dry enough to create the temps needed to control the fan properly. Ok I get it if the wood is not dry it won't create a good temp. But what happens is the fan will cycle on and off when the temps are low, concern that this will eventually harm the AC motor by short cycling .
What I would like to do is replace the limit switch with a temp sensor or possibly leave it and use the arduino to monitor heat chamber and cycle fan on/off at proper temps and possibly ramp fan speed to temps.
Can someone help me with this project , still new to arduino, not sure if it is possible but would appreciate some guidance or direction .
Thanks

Larryfos:
I have a Model 36zc Fireplace extrodinair fireplace which has a rheostat for fan speed and a snap disc limit switch mounted in the chamber wall where the air heats. My issue is the AC fan motor is supposed to come on when the limit sees temp rise approx 110 deg or more, not really sure its setting and when it drops possibly to 90 deg it supposed to turn the fan off. I spoke to the manufacture about its inconstancy of operation and they seem to blame the wood is not dry enough to create the temps needed to control the fan properly. Ok I get it if the wood is not dry it won't create a good temp. But what happens is the fan will cycle on and off when the temps are low, concern that this will eventually harm the AC motor by short cycling .
What I would like to do is replace the limit switch with a temp sensor or possibly leave it and use the arduino to monitor heat chamber and cycle fan on/off at proper temps and possibly ramp fan speed to temps.
Can someone help me with this project , still new to arduino, not sure if it is possible but would appreciate some guidance or direction .
Thanks

Please explain further your concern about motor failure caused by "short cycling"? What is it and what is the harm you envision?

Please explain what type of ac motor you have and how you can adjust the speed?

AC motors fail because heat caused the lubrication in the bearing to fail and then the bearings fail. Is this happening to your motor? Lack of bearing lubrication also causes the motor windings to heat up because of the extra load on the motor. Is this you concern?

Very few AC motors can have the speed controlled as they are designed to only run at the frequency of the commercial AC power in your area.

My suggestion would be to go to the source of your difficulty and that is the thermo switch. Find a replacement with the on/off specifications you need and buy it and replace the one you are dissatisfied with.

Paul

The "problem" is you need a thermocouple for high temperatures and thermocouples need an amplifier. That's quite a bit of complexity just to replace a thermal switch.

Another option would be to wire a regular switch in parallel with the thermal switch. That would give you a manual-on or automatic option.