– 22 –
Symptom
Cause
Remedy
A. Blower does not operate.
B. No voltage at fl ame
safeguard relay (RE-02)
input terminal and the
fan is enabled.
C. Flame safeguard relay
(RE-02) goes into safety
shutdown (lockout).
1. Low or no voltage.
2. Circuit breaker open.
3. Customer interlock not closed or
connected.
4. Fan is disabled.
5. Time clock, night setback
thermostat, or fi eld installed
controls open.
6. Freeze protection tripped. (low
discharge temeprature)
7. DO-1 on UC-01 not energized.
8. RE-57 contacts open.
9. Damper motor not operating,
its end switch not making, or the
damper is binding.
10. Overload Protection on motor
starter tripped.
11. Belts loose or broken.
12. Bearings seized.
13. Motor may be burned or incorrectly
wired.
14. Motor overheating.
1. Heat mode is disabled.
2. Auxiliary switch on starter not
closed (ST-01).
3. Air fl ow switches open.
4. Outside air temperature higher
than Heating Economizer Setpoint.
5. DO-2 or RE-28 not energized.
6. RE-27, 56, or 65 contacts open.
7. High temperature limit thermostat
open.
8. High-low gas pressure switch
open (if applicable).
9. Field supplied purge timer open (if
applicable).
1. See technical cut sheet on fl ame
safeguard relay.
1. Check power source.
2. Check and replace.
3. Close or connect customer inter-
lock.
4. Enable the fan.
5. Check time clock, night setback
thermostat and fi eld installed con-
trols for proper settings.
6. Reset freeze stat by interrupting
power. Check for proper setpoint
and burner operation.
7. See Digital Control System User
Manual.
8. Check power source and/or re
place.
9. Check for power at damper motor
and that end switch has been wired
correctly to the N.O. (normally
open) contact. Check that the link-
age is clear and not binding.
10. Push reset button on starter and
check amps.
11. Turn off power and check belts.
12. Check and/or replace.
13. Turn off power and check motor
and wiring.
14. Check burner fi ring rate.
1. Enable the heating mode.
2. Check auxiliary circuit wiring and
contact.
3. Adjust the air fl ow and external
static pressure to match the rating
plate (Do not adjust switch setpoint).
4. Check setpoint for proper setting.
5. See Digital Control System User
Manual.
6. See Multiplexed Voltage Value Chart.
7. Reset control and correct problem
before restarting.
8. Check gas pressure and reset
switch.
9. Check for power, replace if
necessary.
1. Determine the cause of (lockout).
Push reset button on fl ame
safeguard relay.
SECTION VII - TROUBLESHOOTING
continued
Fan and Heat Mode
(Refer to Digital Control System User Manual for additional troubleshooting suggestions)
