– 48 –
SECTION VII - TROUBLESHOOTING WITH DDC CONTROLS
continued
Cooling Mode
1. Cooling mode is disabled
2. Auxiliary switch on starter (ST-01)
is not closed.
3. Air fl ow switch open.
4. Cooling Changeover and/or
Economizer Setpoints not set
correctly.
5. DO-3 and/or DO-4 are not
energized.
1. Cooling relays (RE-34) (RE-35)
and/or (RE-33) contacts are not
closed.
2. Cooling relays (RE-34) (RE-35)
and/or (RE-33) contacts are not
wired correctly.
3. Compressors or evaporative pump
not running.
1. Incorrect Maximum Cooling
Discharge Temperature Setpoint.
2. Incorrect Minimum Cooling
Discharge Temperature Setpoint.
3. Unit Enable Potentiometer (MP-15)
not set correctly.
4. Cooling Occupied and/or
Unoccupied setpoints not set
correctly.
5. Insuffi cient cooling.
6. Condensing section or evaporative
cooler is not operating correctly.
A. There is no voltage at cooling relays
(RE-34) (RE-35) and/or (RE-33) and
the fan is enabled.
B. Cooling relays (RE-34) (RE-35)
and/or (RE-33) are energized and
condensing unit or evaporative
cooler is not on.
C. Incorrect Space Temperature.
1. Enable the cooling mode.
2. Check auxiliary circuit wiring and
contact.
3. Check for proper CFM. Adjust and/
or replace switch.
4. Change to correct setpoints. See
Digital Control User Manual.
5. See Digital Control System User
Manual.
1. Check and/or replace.
2. Correct wiring.
3. See Troubleshooting Guide for your
condensing unit or evaporative
cooler.
1. Decrease Maximum Cooling
Discharge Temperature Setpoint.
See Digital Control System User
Manual.
2. Decrease Minimum Cooling
Discharge Temperature Setpoint.
See Digital Control System User
Manual.
3. Change to correct setpoints.
See Digital Control System User
Manual.
4. Change to correct setpoint settings.
See Digital Control System User
Manual.
5. If desired Space Temperature is
not reached and cooling is at full
capacity, it may be undersized.
6. See Troubleshooting Guide for your
condensing unit or evaporative
cooler.
(Refer to Digital Control System User Manual for additional troubleshooting suggestions)
Remedy
Symptom
Cause
Summary of Contents for GAS-FIRED HEATERS
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Page 24: ... 24 TYPICAL SEQUENCE FOR MODULATING THERMOSTAT WITH 135 OHM CONTROLS ...
Page 25: ... 25 TYPICAL SEQUENCE FOR MODULATING THERMOSTAT WITH 4 20 mA CONTROLS ...
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