Either;
- Your fan relay is closing for some reason(crud in the contacts)
- or the pump relay is doing this
- thermostat has crud in the contacts somewhere and is sending a false signal.
Disconnect the thermostat (or just the r wire) and monitor. If it is still randomly turning on, it's one of the relays. While you could isolate which one, they are cheap and easy to change. If recommend changing both at the same time. However if the trouble stops, you'll need a new thermostat.
Cheers!
- Your fan relay is closing for some reason(crud in the contacts)
- or the pump relay is doing this
- thermostat has crud in the contacts somewhere and is sending a false signal.
Disconnect the thermostat (or just the r wire) and monitor. If it is still randomly turning on, it's one of the relays. While you could isolate which one, they are cheap and easy to change. If recommend changing both at the same time. However if the trouble stops, you'll need a new thermostat.
Cheers!
