Service & Troubleshooting - Modine Manufacturing MT28 Installation And Service Manual

SERVICE & TROUBLESHOOTING
WARNING
When servicing or repairing this equipment, use only factory-
approved service replacement parts. A complete replacement
parts list may be obtained by contacting Modine Manufacturing
Company. Refer to the rating plate on the appliance for
complete appliance model number, serial number, and
company address. Any substitution of parts or controls not
approved by the factory will be at the owner's risk.
Table 10.1 - Troubleshooting
Trouble
No Gas
Pilot does not light
Pilot goes out on 100%
shut-off when hold down
button is released
Main burners do not light
(Pilot is lit)
Direct spark fails to ignite
main burner(s)
Flashback (burning of
gas/air mixture inside
plenum)
Unit cycles off and on
10
Possible Cause
1. Main gas is off.
2. Power supply is off.
3. Air in gas line.
4. External regulator malfunctioning.
5. External regulator reversed.
1. Main gas is off.
2. Power supply is off.
3. Air in gas line.
4. Dirt in pilot orifice.
5. Gas pressure out of proper range.
6. Pilot valve does not open.
7. No spark at igniter.
a. Loose wire connections.
b. Pilot sensor is grounded.
c. Defective ignition controller.
1. Defective pilot interrupter in combination gas
valve .
2. Defective pilot flame sensor.
3. Insufficient heat on pilot flame sensor.
4. Improper pilot flame sensor location.
5. Connection is poor contact at valve end of the
sensing element.
6. Low gas pressure.
1. Defective valve.
2. No electrical power to gas valve.
3. Defective pilot sensor.
4. Defective ignition controller.
5. Improper thermostat wiring.
6. Manual valve closed on combination gas valve.
1. Electrode improperly located
2. Electrode ceramic cracked
3. Electrode wire is loose, broken, or frayed.
4. Low manifold gas pressure.
5. Gas valve fails to open.
6. Ignition detection control defective.
1. Heater mounted at incorrect angle.
2. Excessive drafts.
3. Gas leak at manifold, gas valve, and/or pilot
tube connections.
4. Separation of ceramic tiles.
5. Ceramic grid(s) cracked.
1. Insufficient heat on pilot element.
2. Excessive drafts.
CAUTION
Do not attempt to reuse any mechanical or electrical
controllers which have been wet. Replace defective controller.
IMPORTANT
To check most of the Possible Remedies in the troubleshooting
guide listed in Tables 10.1 and 11.1, refer to the applicable
sections of the manual.
1. Open manual gas valve.
2. Turn on main power.
3. Purge gas line.
4. Replace external regulator.
5. Remove and install regulator properly.
1. Open gas shut-off valve.
2. Turn on main power.
3. Purge gas line.
4. Check for plugged pilot orifice and clean
with compressed air if necessary.
5. Adjust to a maximum of 14" W.C.
Minimum for Natural Gas - 7" W.C.
Minimum for Propane Gas - 11" W.C.
6. Check wiring for 24 volts to valve.
Defective ignition controller or gas valve.
7.
a. Check all ignition controller wiring.
b. Replace sensor if cracked or worn.
c. Replace ignition controller.
1. Replace combination gas valve.
2. Replace pilot flame sensor.
3. Check pilot orifice for size. Clean pilot burner.
4. Check position with respect to pilot.
5. Insure clean and tight contact.
6. Provide proper gas pressure.
1. Replace valve.
2. Check wiring to gas valve.
3. Replace pilot sensor.
4. Replace ignition controller.
5. Verify wiring compared to diagram.
6. Turn knob to ON position on combination
gas valve.
1. Relocate to correct position.
2. Replace electrode
3. Reconnect loose wire or replace broken or
frayed wire and/or electrode.
4. Provide proper gas pressure.
5. Replace gas valve.
6. Replace ignition control module.
1. Angle to be 10
2. Shield or relocate heater from drafts.
3. Check all connections with soap solution
and tighten as necessary.
4. Replace burner assembly.
5. Replace burner assembly.
1. Check pilot orifice, clean pilot burner.
2. Shield or relocate unit from drafts.
Possible Remedy
° °
to 35 from horizontal.