Furnace Fan Not Running

Quick question for you guys since I don't want to bug my builder on a Sunday. Hoping it's something silly.

When I turn on my "ventilation" switch, normally the furnace fan runs and blows cool air and it's connected also to the main floor bathroom exhaust fan. That is how it has worked 100% of the time up until today. Now, when I turn on the ventilation switch, just the bathroom exhaust fan runs, and the furnace/fan does not turn on at all.

Status light on the furnace says it's operating normally. Breaker is obviously fine as I can see the status light. Anything else I can check?

Is your thermostat thingie set to fan? Mine used to do the same thing as yours, and then my circuit board croaked. Had it replaced by a forum member and the ventilation switch no longer works as well, just the bathroom exhaust fan. Never bothered looking into why

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Originally Posted by dj_rice

Is your thermostat thingie set to fan? Mine used to do the same thing as yours, and then my circuit board croaked. Had it replaced by a forum member and the ventilation switch no longer works as well, just the bathroom exhaust fan. Never bothered looking into why

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It's still set to "heat", I just have the thermostat set to 17C (so it doesn't try to heat), and the inside temp is 23C. It's been like this forever though and turning on the ventilation switch has always just turned on the furnace fan to blow nice cool air into the house up until this morning.

Fan is set to "auto". I also found a setting where it looks like the furnace was set to run the fan for 20 mins every hour to circulate air, which it definitely did not do. It would tun on a few times throughout the day though just to run the fan, which I assume is normal operation.

Nothing has changed in the last ~6 months, so when it didn't work today I got the feeling something was wrong/broken.

If you change the fan setting to On instead of Auto does it kick on?

Fan on auto will only run when heat is triggered. Set fan to on and it will fire right up.

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Originally Posted by sabad66

If you change the fan setting to On instead of Auto does it kick on?

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There is no way for me to change the fan setting, that I can figure out anyway. There is a fan section in the menu, however all it lets me do is select the duration it will automatically run every hour, and it doesn't seem to pick up that setting at all anyway.

It came on by itself as I am used to and I timed it this time, so it comes on periodically for exactly 3 minutes, maybe 5 times a day. So I know it works at least. I just can no longer trigger it with my "ventilation" switch (separate from the thermostat).

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Originally Posted by killramos

Fan on auto will only run when heat is triggered. Set fan to on and it will fire right up.

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I don't appear to have that option, unless I just can't figure out how to trigger it. In my "Fan" menu, the only options I am presented with is making a schedule for the fan, which it doesn't follow.

The issue though is with my "ventilation" switch (just a standard switch that is on the wall below my thermostat). Up until today, flipping that switch turned on my bathroom exhaust fan and the furnace fan, but now I can't trigger the furnace fan manually no matter what I do. The fan on the Thermostat has always been set to "auto" when things were working properly, so I don't know what may have changed.

The Thermostat itself is a Lennox iComfort M30, and the manual doesn't even have a section on fan operation unfortunately. I'm not convinced it's a thermostat issue though, since it's behaving as if the wire that triggers my furnace fan when I flip the ventilation switch was cut.

Thanks!

Interesting you don’t have the option. If I remember correctly you have one of those newer HRV ventilation systems? Maybe fan is controlled with that instead of the thermostat? Got no experience with those systems myself but maybe someone else can chime in

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Originally Posted by sabad66

Interesting you don’t have the option. If I remember correctly you have one of those newer HRV ventilation systems? Maybe fan is controlled with that instead of the thermostat? Got no experience with those systems myself but maybe someone else can chime in

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Yeah, I have some fancy new furnace that I don't know how to use lol. It's so different than any home I have ever lived in before so I am finding I have a lot of questions. The builder is coming by today to fix it, he thinks it's just the relay in the switch that triggers the furnace fan along with the ventilation fan. We will see.

I am hoping to get an education on some stuff as well while they're here.

EDIT: Apparently, since I have an HRV, the bathroom exhaust fan should never have been hooked up to the furnace fan anyway. They're coming back next week to sort it all out I think. Probably going to get some AC installed while the're at it because my upstairs is hot af with west facing windows. Anyway, thanks for everyone's suggestions.