Goodman roof package unit, apg156014041, heat won't start when it's cold outside

Hi

Homeowner with package unit on the roof in southern California.

Goodman apg156014041

House temp was down to 55 the other morning and the interior decorator wanted heat. First time since summer, turned it on at thermostat, thermostat says "heat on" hear a click, nothing happens. Turned off an on a couple times, checked circuit breakers, all is well, called HVAC guy, left it on.

Sun comes up, shines on the unit, starts up like nothing was wrong, runs normally the rest of the day.

Next morning, same story, 5 AM, it's dark, low 50's outside, no heat. HVAC guy comes, replaces ignitor and flame sensor.

Next morning same problem, no heat, sun comes up, shines on the unit, heat comes on.

Ideas? Gas valve? Control board?

Thanks in advance

RC

source https://hvac-talk.com/vbb/threads/2243698-Goodman-roof-package-unit-apg156014041-heat-won-t-start-when-it-s-cold-outside?goto=newpost