Hi Having a problem with my Reznor XA-150 hanging garage heater. It goes on fine on the first cycle - pilot lights (no problem, new thermocouple 2 yrs ago), main burner lights fine, delay before fan comes on (normal, I understand) and heater runs for a while. BUT, after a while the fan stops and...

i have a reznor tcore3 in my hot yoga studio. installed 2002, been blazing since then. lately, when it gets to around 90 degrees, it gets stuck in the cooling cycle. there's a call for heater, the burner lights, burns for about a minute, then turns off and the blower turns on. it runs for a...