Mr heater big maxx heat startup cycle issue

[segermech]

I have a new big max heater 75k. And most of the time it works no problem... Vent blower turns on, burner fires, Then the fan kicks on. Weird but sometimes the blower turns on then the fan kicks on for like 2 minutes before the gas turns on. Anybody have an explanation for this???

Thanks

 

[Erampu]

It's made in China.

 

[dave67fd]

Could be an intermittent/erratic pressure or rollout switch, temp sensor, issue with the control board or even a loose connection. Do you have any obstructions with the heater?
If using a programable thermostat, it could be noise causing erratic function. Probably should have it inspected or call customer support.