Enviro Milan Stuck on High

[gtgoat]

I picked up a used Enviro Milan fireplace insert. The previous owners wife didn't like it because it was too noisy. I installed it in my house and as soon as I plugged it in the fans sounded like they were running on high. I hadn't even hit the power button yet. I let it run for about 3 hours and periodically adjusted the settings from low to high and the fan noise never changed. I hit the power button and shut the unit down. The convection and exhaust fans continued to run. I let them run for an hour before unplugging the unit.

Any ideas on what is causing this?

The serial number is 1877## so I think this is an early model.

I also uploaded a picture of the circuit board. The thermostat wires are jumped together so there is no thermostatic control.

Thanks.

 

[johneh]

I suspect that the Ceramic Fan Temperature Sensor is shorted . try unplugging it
2 brown wires only need to take one off . If fans stop check
it with a meter ,also try removing it and cleaning.
Here's a link to the manual
http://www.enviro.com/images/manual...struction Milan Domestic Technical Manual.pdf

 

[gtgoat]

I disconnected a brown wire and it didn't change anything. The fans still ran at high speed. I tried testing the continuity on the Ceramic Exhaust Fan sensor and it showed as "open" so I guess it's not shorted.

While I had the meter out I checked the High Limit Temperature sensor. It showed as "closed".

 

[gtgoat]

I did some more research online and determined the manufacturer updated circuit board for the Milan. My unit has the old style board. I would hate to buy a new board just because I "think" the old board is bad.

Does anyone have any ideas on how to test the circuit board? Is there a reset button on the circuit board?

 

[gtgoat]

In case someone can help, here is some more information.

I jumped the wires that go to the exhaust temp sensor - The auger turned off
I disconnected the wires on the high temp limit switch - The auger turned off and the #2 light was flashing
I disconnected the wires that go to the vacuum switch - The auger turned off

As far as I can tell, all these test produced the correct outcome. Why would the convection fan an exhaust fan always sound like they are running on high? What makes the convection fan turn on/off or vary the speed?