4.If 24 volts is present, remove the pilot burner and remove the pilot orifice from the pilot burner. The orifice is removed in the direction opposite the flow of gas. Inspect the orifice for obstruction. If it is clear, replace the main gas valve.
The ignitor sparks at the pilot burner but the pilot does not ignite and a gas odor is detected at the draft motor outlet.
1.Adjust the pilot adjust screw on the gas valve as described in “PILOT CHECKOUT” page 44.
2.Check the supply pressure as described in “POST START CHECK LIST” page 43. Make adjustments as necessary.
3.Check the pilot orifice for obstruction as described in paragraph above. Clean as needed but the prob- lem should not be the gas valve.
The pilot burner ignites but the ignitor continues to spark and the main burners do not ignite.
1.Make the same checks and adjustment as described in “PILOT CHECKOUT” page 44.
2.Check the supply pressure as described in “POST START CHECK LIST” page 43. Make adjustments as necessary.
3.Make sure that the pilot burner is not bent or dam- aged.
4.Make sure that the ground connections at the pilot burner, gas valve and ignitor control are intact. Check the high tension wire for good electrical con- nection. If all are intact, replace the ignitor module.
The pilot burner lights and the spark stops but the main burners do not light.
1.Check electrical connections between the ignitor control and the gas valve. If intact, check for 24 volts across terminals “MV” and “COMMON” termi- nals. If no voltage detected, replace ignitor control. If voltage is present, replace gas valve.
Furnace lights with
1.Make sure that the pilot burner is aligned properly with the carryover as described in “PILOT CHECK- OUT” page 44.
2.Make sure that the carryovers on adjoining burners are screwed fast and are level with respect to one another.
Main burners light but exhibit erratic flame characteris- tics.
1.Adjust air shutters as described in “BURNER AIR SHUTTER ADJUSTMENT” page 44.
2.Check the main burner orifices for obstruction and alignment. Removal procedure is described in BURNER INSTRUCTIONS page 44. Clean or replace burner orifices and burners as needed.
UNIT FLASH CODES
Various flash codes are utilized by the unit control board (UCB) to aid in troubleshooting. Flash codes are distinguished by the short on and off cycle used (approximately 200ms on and 200ms off). To show normal operation, the control board flashes a 1 second on, 1 second off "heartbeat" during normal operation. This is to verify that the UCB is functioning correctly. Do not confuse this with an error flash code. To prevent confusion, a
Alarm condition codes are flashed on the UCB lower left Red LED, See Figure 24. While the alarm code is being flashed, it will also be shown by the other LEDs: lit continuously while the alarm is being flashed. The total of the continuously lit LEDs equates to the number of flashes, and is shown in the table. Pressing and releasing the LAST ERROR button on the UCB can check the alarm history. The UCB will cycle through the last five (5) alarms, most recent to oldest, separating each alarm flash code by approximately 2 seconds. In all cases, a flashing Green LED will be used to indicate
In some cases, it may be necessary to "zero" the ASCD for the compressors in order to perform trouble- shooting. To reset all ASCDs for one cycle, press and release the UCB TEST/ RESET button once.
Flash codes that do and do not represent alarms are listed in Table 24.
52 | Johnson Controls Unitary Products |
