Recently we ran into an issue that caused the heater not to run. Upon end of the cooling season, and temperatures dropping rapidly, our new customer called and reported that he had an Air Conditioner installed by a different company and could not get a hold of them, now that the heater does not heat.
Twinning is used to pair up two furnaces to work in unison. Since there is just one single furnace that is not paired up (or twinned) with any other furnace, the twinning circuit was the best faulty candidate.
Rheem Furnace Troubleshooting
Upon closer inspection we noticed that yellow wire from thermostat and red wire to A/C condenser unit were screwed to the TWIN post on the control board instead of he post marked “Y”. During cooling season this setting awkwardly worked, but since heating operation differs from cooling operation, the furnace would not start.
Simply moving the above mentioned yellow thermostat and red condenser unit wire solved the problem and the furnace started working as normal. Whether that was an installation job done in a hurry or the other company’s tech was inattentive, but a simple wiring issue led to unusual furnace behavior.
To sum up, 5 blinks followed by a 2 second pause means twinning fault. If twinning is not used for a particular furnace, the twinning circuit has to be closely inspected. Various reasons like a lose wire touching terminals, or improper wiring, dust collected around the terminals, loose solder remnants may short the contacts and cause the furnace to not start.
We invite you to call us to schedule your furnace service appointment today!
