OWNER’S MANUAL
TROUBLESHOOTING
Note: For additional help, visit DESA International’s technical service web site at www.desatech.com.
Note: All troubleshooting items are listed in order of operation.
WARNING: Turn off and unplug furnace and let cool before servic- ing. Unless you need gas supply for testing, shut off equipment shutoff valve before servicing. Only a qualified service person should service and repair furnace.
OBSERVED PROBLEM | POSSIBLE CAUSE | REMEDY | ||
No heat | 1. | Thermostat off | 1. Check to be sure thermostat is calling for heat. | |
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| Wire to thermostat could be off terminal |
| 2. | Gas supply | 2. Be sure equipment gas valve is in the open posi- | |
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| tion (level or parallel to gas line) |
| 3. Electrical connections and power | 3. Be sure all electrical connections are secure | ||
| 4. | Motor | 4. | Motor must be operating at top speed before |
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| burner will come on. If blower is not operating |
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| at top speed, check voltage supply (minimum |
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| 100 volts A.C.). If voltage supply is okay, check |
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| for defective motor |
| 5. | Malfunctioning microswitch | 5. Be sure the microswitch is sailing in far enough | |
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| to open the solenoid valve and to energize the |
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| ignition control. If the switch is not sailing in, |
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| clean any dust or dirt from the actuator pin. Other |
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| reasons for the switch not sailing in are |
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| A. Insufficient blower speed - Slow motor due to |
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| faulty motor or lint and dust accumulation on |
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| the blower wheels or restriction of return air to |
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| the furnace |
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| B. Faulty microswitch - Replace switch if cir- |
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| cuit to ignition control is not completed when |
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| switch is manually engaged. Switch should |
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| also be replaced if blower motor running at |
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| top speed fails to engage switch within six or |
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| seven seconds. Note: To service switch, com- |
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| bustion chamber must be pulled out. Follow |
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| steps 1, 2, 3, 9 and 10 on page 8 to remove |
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| combustion chamber |
| 6. | Gas valve | 6. | Within 20 seconds after motor reaches 75% of |
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| its r.p.m. and microswitch engages, check the |
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| following: |
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| A. Voltage at valve - If current is present but |
valve is not opening, check wire connections B. If wire connections okay - Replace valve C. No voltage at valve - Check circuit completion
through microswitch and limit switch as well as wiring and wire connections. If no defects are found, see Ignition Failures, page 16
www.desatech.com | Continued |
201835 | 15 |