Interesting Issue with Fan-Tastic Vent

Dennis M · December 25, 2015

We have three Fan-Tastic Vents all with auto temp control, recently one started acting strange. It had developed a mind of it’s own, a couple of times we came home and found it open and running. On the auto setting you could not change temp and on the manual setting the speed could not be changed, and it would not turn off, just come right back on. So I pulled the knob out to put it on manual - then it started running randomly until I pushed the knob back in and let it register as closed! Finally I just pulled the fuse until I could take a look at at it.

I know I could have just called them and they probably would have sent a new controller no charge, but I like to find out what's wrong with things like this.

Thinking old fashioned I thought it might be dust on contacts in the switch box, so I blew some compressed air into it. That made a change in the lights that were staying on so I and opened up the box. Oops, solid state circuit board, so my dust theory went by the boards. However, Looking at the back of the circuit board I could see that there was some kind of substance which looked like a liquid had run down the board and dried out. It looked like it could be shorting out the board.

I took a paper towel with hot water and the stuff came right off. Let it dry for a couple of hours, put the fuse back in, and it worked perfectly! Thinking about it, last year in Denver when we hit that brutally cold snap (14 below) we had a fair amount of condensation. There is a 1” square hole in the wall behind the control box and I bet cold air flowing in there caused condensation on the circuit board that left a deposit when it evaporated.

Anyway, the vent is working fine now.

Pat & Pete · December 25, 2015

If you disconnected that board , the cause may have been a poor connection and your action of dis and reconnecting could have been enough to establish a better connection .

Dennis M · December 25, 2015

If you disconnected that board , the cause may have been a poor connection and your action of dis and reconnecting could have been enough to establish a better connection .

Nope, did not disconnect, just pulled the fuse before I opened it up.

Kirk W · December 25, 2015

Having made a living for 40 years doing the sort of work that you just went through, I find it very possible that you found and corrected the problem. I might suggest that should you ever have similar problems in the future, it would be better to disconnect the circuit board from the system before cleaning, as it is the only way to be 100% sure that no power is there, even though most is gone in turning things off. The other suggestion is that you use distilled water for the cleaning to avoid any chance that hard water will leave behind any sort of problem. If you want to be totally sure, use rubbing alcohol and the very best electrical cleaning solvent is pure grain alcohol, or as nearly so as you can get. But over all, your thought process and the solution was the same as I would have done.

You may want to take a look at possible ways to prevent any moisture intrusion in the future from any source as if that should happen while the circuit is active, it is very likely that permanent damage could result. Congratulations on some good trouble shooting!