Troubleshooting Flow Chart (Furnaces Equipped With Fan Control Module Board) - Suburban SFV-30 Service Training Manual

SUBURBAN RV FURNACES with FAN CONTROL MODULE BOARDS
Thermostat Closes
▼
▼
YES
▼
▼
▼
▼
▼
▼
Blower is operating at call for heat
▼
YES
▼
Motor is operating
YES
After fifteen (15) seconds, the module
creates spark and opens valve
▼
▼
YES
▼
▼
Spark occurs for approximately seven
(7) seconds and main burner flame
establishes
▼
▼
▼
▼
▼
YES
▼
▼
▼
Thermostat opens and the module board
operates the fan for the cool down cycle.
YES
SYSTEM OK
TrOublE ShOOTinG GuiDE
12 VDC HEATING SECTION
Check thermostat wire connections, contact
- NO →
points and the heat anticipator.
Check 12VDC at BLuE wire, check the amp
draw to the thermostat.
Check components amperage.
Check for 12VDC at Furnace
Check fuse or circuit breaker
Check for 12VDC at power terminal on
- NO → module board and for 12VDC to RED wire
leading to the motor.
Check GROuND wire on terminal block
RESET thermostat. Motor operating.
- NO → Check for 12VDC at BLuE wire on Molex
Check for 12VDC between RED and
- NO →
YELLOW wires at the Module Board
Check for 12VDC at Limit Switch,
Check for 12VDC at Sail Switch,
- NO → No spark at the electrode
Check for 12VDC at Gas Solenoid Valve
Did the Gas Valve Open?
Check for restriction in combustion air
intake (wasps, insects, etc.)
is flame established?
- NO → Replace the Module Board
- YES →
No
▼
- YES →
No
▼
Check for shorts.
- YES →
YES
- NO →
YES
▼
- NO →
YES
▼
- NO →
YES
▼
- NO →
- YES →
Edge Connector
- YES →
No
▼
- YES →
on both sides
No
▼
- YES →
on both sides
- NO →
YES
- NO →
YES
▼
- NO →
YES
▼
- NO →
NO
▼
- NO →
31
Clean points, secure loose connections,
replace thermostat if anticipator is shorted.
Replace Thermostat.
Repair or replace connection or parts with
higher than normal amp draw.
Check ON/OFF Switch on Furnace
Replace fuse/Reset Breaker
Replace the Module Board
after confirming motor operation
Replace the module board after confirming
motor operation
Verify voltage thru limit and sail switch
to module board. If circuit remains open
for 30 seconds, module board will go into
lockout and shut down motor. RESET
thermostat. Replace defective part.
Check plug connection tot he Module-
Electrode and Wire-Spark gap 1/8"
between probe and ground
Replace the Sail Switch
Replace the Limit Switch
Replace the Module
Replace the Module
Check gas pressure at the manifold or for
restrictions in burner orifice
NO
▼
Replace the gas valve
Check flame contact to electrode. Flame
should be hard blue