Service And Troubleshooting - Modine MDB Série Manuel D'installation Et De Maintenance

service and trouBleshootinG

trouble
F. No Pilot
G. Pilot Will Not Prove
H. Erratic Temperature
I. Unable to Achieve High Fire.
J. Unable to Achieve Low Fire.
K. No Gas Flow
L. Unable to Achieve Desired
Discharge Temperature, or
Space Temperature
M. Floating 75/25 Damper
Functioning Incorrectly or
Not Functioning
damaged, or disconnected.
N. Two Position 70/30,
75/25 Dampers Not
Functioning
If the preceding service diagnostics do not solve your problem, contact your local Modine Manufacturing sales representative for further assistance.
Please be sure to have the complete model number and serial number from the unit's rating plate available before calling for service
Possible cause
1. No gas to pilot.
2. Dampers not functioning.
3. Pilot tube plugged or damaged
4. Freeze stat failure.
5. Inlet On/Off stat failure.
6. Flame safeguard in lockout
7. Failed flame safeguard.
8. Failed air flow switch
9. Too high or low gas pressure.
10. See Problem "E" – No Burner
1. Inadequate signal to safeguard
control.
2. Insufficient gas pressure to pilot.
3. Loose lead wires.
4. Soiled flame rod.
5. Moisture on flame rod lead.
6. Defective flame rod.
7. Defective flame safeguard.
8. Short in sensing leads.
9. Excessive air velocity across burner.
1. Defective temperature selector or
sensor.
2. Temperature sensor subject to poor
air flow or located in drafty area.
3. Discharge sensor blocked by duct
insulation.
4. Faulty amplifier or proportioning motor.
1. Low gas supply pressure.
2. Modulating controls improperly set.
3. Faulty temperature sensor.
4. Faulty amplifier or proportioning motor.
1. Modulating controls improperly set.
2. Faulty temperature sensor.
3. Faulty amplifier or proportioning motor.
1. Manual gas valve(s) closed.
2. See Problem "E", Items 2 thru 14
1. Temperature sensors improperly set or
faulty.
2. Improper gas supply pressure.
3. Faulty amplifier or proportioning motor.
4. Air flow too high.
5. Burner capacity undersized.
1. Defective building pressure switch.
2. Pressure switch improperly set.
3. Pressure switch pick-up tubes blocked,
4. Outdoor pressure pick-up tube not
routed to outdoors.
5. Faulty damper motor.
6. Dampers binding.
7. Damper linkages loose.
8. No power to damper motor.
1. Damper position selector switch or
relay defective.
2. Faulty damper motor.
3. Dampers binding.
4. Damper linkages loose.
5. No power to damper motor.
7-500.10
Possible remedy
1. Check hand valve and pilot solenoid
valve.
2. See Problem "B"
3. Check and repair/or replace.
4. Check and/or replace.
5. Check and/or replace.
6. Check and reset.
7. See vendor's instructions shipped with
unit.
8. Check and/or replace.
9. Check pressure switches and gas
pressure.
10. See Problem "E" Operation.
1. Check flame signal Vdc. See vendor
literature for type of flame safeguard
supplied with unit.
2. Check and adjust.
3. Check and correct.
4. Clean and/or replace.
5. Check and dry leads.
6. Check or replace. See vendor literature
shipped with unit.
7. Check or replace. See vendor literature
shipped with unit.
8. Check and repair.
9. Check burner velocity and correct.
1. See vendor literature shipped with unit.
2. Check sensor location and move if
required.
3. Check and remove blockage
4. See vendor literature shipped with unit.
1. Check and adjust.
2. See vendor literature shipped with unit.
3. Check and/or replace.
4. See vendor literature shipped with unit.
1. See vendor literature shipped with unit.
2. Check and/or replace
3. See vendor literature shipped with unit.
1. Open manual gas valve(s).
2. See Problem "E", Items 2 thru 14
1. Adjust or replace.
2. Check and correct.
3. See vendor literature shipped with unit.
4. Check blower speed and/or burner
velocity differential pressure.
5. Check rating plate for conformance to
design specifications.
1. Check and/or replace.
2. See vendor literature shipped with unit.
3. Check and repair or reconnect.
4. Route tube to outdoors.
5. Check and/or replace.
6. Check and repair.
7. Check and retighten.
8. Check power supply to motor.
1. Check and/or replace.
2. Check and/or replace.
3. Check and repair.
4. Check and tighten.
5. Check power supply to motor.
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