Heating, Air Conditioning, Fridge, HVAC/Rheem gas forced air furnace


Have 25+ year old Rheem forced air gas furnace. It heats fine, but after running awhile only the draft motor runs, and the heat does not work again until I power-cycle the entire unit.  THIS ONLY HAPPENS SOMETIMES.  Often the heat cyles on and off just fine.

Other info: Spark ignition - Honeywell S8610U module.
Burners are fully visible.

I tried setting the blower to full on when the problem was happening (instead of auto) and it made no difference. Power-cycling the entire furnace again caused the burners to light, and just about instantly.

Again this problem is intermittent.  But I'd like a solution.

The fact your furnace is working is good, considering the mess up there right now.  The problem can be any number of things from a safety kicking out to a control board not wanting to work properly all of the time.  A power down to reset normally leads to a lock out fault.  That can be from a flame failure, flame rollout or even overheating.  Look to see if the control board has a flashing light.  When it trips the light will blink to indicate why it shut down.


Heating, Air Conditioning, Fridge, HVAC

All Answers

Answers by Expert:

Ask Experts


Craig HVAC Expert


I have been in the HVAC field for the past 18 years. I can help with most HVAC questions. I work on commerical buildings for the most part, and have yet to find anything I could not troubleshoot and repair, when repairable. I work on small 1 ton units to a 2500 ton chiller. Troubleshoot air flow, elect, and control problems. I attend regular classes to keep up with the latest and greatest.


I work on commerical sites, hospitals, gov't buildings. I can troubleshoot just about anything in the HVAC business.

5 years trade school, VFD training classes, Liebert factory training, some York and Trane factory training.

©2017 About.com. All rights reserved.

[an error occurred while processing this directive]