This display indicates that the 24 volt power supply on the control is damaged or overloaded. This code resets automatically if it is the result of an overload and that overload condition is removed. The second line indicates the status of the pump. Note that while 24 volt power is low, the pump output will be on.
- Check line voltage. It must be between 100 and 128 volts.
- If available, connect PC, and using HTP service software check the 24v supply display in the lower left corner of the screen. The number displayed here must be greater than 128 and should be no greater than 250. Use this as a troubleshooting guide as you follow the steps below.
- Remove the 10 pin Molex connector from customer connection board. If the message clears, then the problem is with the external sensor wiring. Examine the external sensor wiring for shorts to the ground, repairing as necessary. If the message is still present and the boiler is so equipped, disconnect the UL 353 low water cut-off to see if the message clears. Replace the faulty part. Check the low voltage wire harness in boiler for shorts to ground.
- If a message only occurs when the burner tries to light, check the gas valve for exces-sive current draw.
- If a message is present with the low voltage harness disconnected from the 926 control board, replace the 926 control board.
