Page 14
TABLE 10
DIAGNOSTIC CODES
Diagnostic LEDs are labeled DS1 and DS2. See figure 14 for location of diagnostic LEDs.
DS1
DS2
DESCRIPTION
SIMULTANEOUS
SLOW FLASH
SIMULTANEOUS
SLOW FLASH
Power on − Normal operation.
Also signaled during cooling and continuous fan.
SIMULTANEOUS
FAST FLASH
SIMULTANEOUS
FAST FLASH
Normal operation − signaled when heating demand initiated at thermostat.
SLOW FLASH
ON
Primary limit or rollout switch open. Limits must close within 3 minutes or unit
goes in to 1 hour Watchguard.
OFF
SLOW FLASH
Low−fire pressure switch open (G32Q−75 only);
OR: Blocked inlet/exhaust vent;
OR: Low pressure switch closed prior to activation of combustion air inducer.
OFF
FAST FLASH
High−fire pressure switch open
OR: Blocked inlet/exhaust vent;
OR: High pressure switch closed prior to activation of combustion air inducer.
ALTERNATING
SLOW FLASH
ALTERNATING
SLOW FLASH
Watchguard −− burners failed to ignite; OR limit open more than 3 minutes;
OR lost flame sense 5 times in one heating cycle;
OR pressure switch opened 5 times in one heating cycle.
SLOW FLASH
OFF
Flame sensed without gas valve energized.
ON
ON
ON
ON
ON
OFF
Circuit board failure or control wired incorrectly. Check 24 and 115 volts to board.
O
OFF
O
ON
Circuit board failure or control wired incorrectly. Check 24 and 115 volts to board.
FAST FLASH
SLOW FLASH
Main power polarity reversed. Switch line and neutral.
SLOW FLASH
FAST FLASH
Low flame signal. Measures below .23 microAmps. Replace flame sense rod.
ALTERNATING
FAST FLASH
ALTERNATING
FAST FLASH
The following conditions are sensed during the ignitor warm−up period only:
1) Improper main ground;
2) Broken ignitor; OR: Open ignitor circuit;
3) Line voltage below 75 volts.
(If voltage lower than 75 volts prior to ignitor warmup, control will signal waiting on
call from thermostat, and will not respond.
NOTE − Slow flash rate equals 1 Hz (one flash per second). Fast flash rate equals 3 Hz (three flashes per second).
Minimum flame sense current = 0.17− 0.22 microAmps.