Modine Manufacturing HD Manual page 152

Four Flashes – Unit Sparks, Lights Flame and
Shuts Down After 10 Seconds
The information below is related to situations where the unit DOES SPARK and then
SHUTS DOWN within 10 seconds:
This usually occurs as a result if the safety switch circuit is open:
• Pressure switch is open
Unit Sequence:
• Green light on, call for heat
• Power exhauster cycles on, burner lights, no yellow flame light on board,
burner shuts down after 10 seconds. Fan motor never cycles on.
Possible Causes:
• Reversed polarity:
– To check for reversed polarity:
1. Remove the call for heat
2. Measure voltage across terminal L1 and case. It should be 115 VAC
3. Measure voltage across terminal NEUTRAL and case.
It should be 0 VAC
4. If the readings are backwards, shut off power, then reverse LI and
neutral wires coming from the panel to the unit
• Loose flame sensor wire
• Dirty or defective flame sensor, not sending micro-amps to board:
– Clean sensor with emery cloth
– If issue is not resolved, verify and replace sensor
• Defective board
– Getting correct micro-amps from sensor, but not allowing unit to ignite
– For more information on fixing or replacing a defective board,
reference page 23.
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Hot Dawg Troubleshooting Guide
®