Rheem and 1 hr lock out ?

[sonnyd]

trying to figure out whats going on with a rheem classic 90 +. It stoped worikng last week, I opened it up to check it out and didnt see anything wrong. came back later and it seemed to work fine.
It died again yesterday and gave it another look, this time I looked at the manual and there was a referance to a blinking LED. the code for the said 1 HR lockout.
The manual that was left does not explain the problem or cure for this.
Anyone know whats up ?

Thanks
Sonny D

[BaldLoonie]

I believe the new boards will lockout for several reasons. Repeated flame sense loss, repeated limit opening, possibly repeated pressure switch opening. Check flame sense current with a micro-amp-meter or if you don't have one, make sure the sense LED is on. Check temp rise and watch to be sure it doesn't open the limit.

[weezer]

Check the flue and intake for debris. A slight drop in differential will cause a hard lock out, usually at this time of the year.