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30 Direct-Fired Indoor and Outdoor Units • MUA-SVP01A-EN
Diagnostics
– No. See the Diagnostic section for Unit On/Fan Off.
– Yes. Continue.
SOLUTION:If fan is running (check prior alarm log)
1. Is the high temperature limit tripped?
– Yes. Determine cause and rectify.
– No. Continue.
2. Is the low gas pressure switch closed?
– No. Verify the inlet gas pressure is as specified on the gas piping diagram.
The low gas pressure switch setpoint should not be adjusted. The inlet gas
pressure must remain as specified when unit fires at full input. Correct gas
pressure and reset switch. If the switch cannot be reset, replace it. See
Installation, Operation and Owners Manual for more information.
– Yes. Continue.
3. Is the high gas pressure switch closed?
– No. Verify the firing rate pressure at full input is as specified on the unit
rating plate. The high gas pressure switch setpoint should not be adjusted.
The firing rate pressure must remain as specified when unit fires at full
input. Correct gas pressure and reset switch. If the switch cannot be reset,
replace it. See Installation, Operation and Maintenance Manual for more
information.
– Yes. Continue.
4. Is the safety circuit relay energized?
– No. Check for loose wiring and rectify.
– Yes. Continue.
5. Is the safety circuit relay's normally open contact closed?
– No. Replace the relay.
– Yes. Continue.
6. Is there continuity at the controller between the safety status terminals?
– No. There is an open in the wiring between these terminals. Determine
cause and rectify.
– Yes. Replace controller.
FAULT CODE:Burner Status
PROBLEM: The controller has activated the burner enable output, but the
burner status input is not receiving a signal that the burner is on.
SOLUTION:Inspect burner control circuit and burner
1. Is there a prior alarm such as Unit On/Fan Off, Airflow Sw., or Safety Circuit?
– Yes. See the Diagnostic section for the previous alarm.