Rinnai RHFE-551FA Service Manual page 41

Troubleshooting
(FM) Convection Fan Motor:
Read voltage across:
Black-Red
* Be sure to check for obstructions to blades. Check the capacitor before replacing motor.
(PS) Pressure Sensor:
Omron Electronic
Note: Insure clear and black hose from pressure switch to blower air chamber is not blocked or
crimped with any obstructions including spider webs.
(TF 216ºC, OHS1 90ºC, OHS2 70ºC)
Disconnect connector G from PCB. Check for continuity reading from Pin #1 to Pin #5 on the wiring
harness White to White wires. If you do not read continuity through this circuit, locate open thermal
fuse, bimetal OHS1, or bimetal OHS2, and replace. You must immediately determine what caused
the overheat situation and correct. Check combustion specifications, gas pressures, gas type, and
for any obstructions to air flow.
(R.TH) Room Thermistor:
Disconnect connector H from PCB. Set your meter to the 200K Ω scale. Place your meter leads into
Yellow to Yellow. Apply heat to the thermistor bulb. The resistance will decrease. Apply cold and the
resistance will increase. Examples of readings:
41ºF=91KΩ
(OH.TH) Over Heat Thermistor:
Disconnect connector H from PCB. Set your meter to the proper Ω scale. Place your meter leads
into White to White. A reading below 0.38kΩ indicates a short. A reading above 1255kΩ indicates
an open circuit or broken wire. Insure air flow is not obstructed.
(FR) Flame Rod
Set your meter to read micro-amps (µ). Disconnect connector C1 and place your meter in series
with the Yellow to Yellow wires. Upon flame development you should read 1 -2 micro-amps.
Depending on gas type and firing rate you should read 4 to 8 micro-amps. You must have a
grounded and polarized electrical supply with no obstructions in burner or build up on flame rod to
proof flame. The micro-amp symbol on your meter is µ.
(Hard Lock Out Information)
Improper sized gas lines, low pressure drops, defective or freezing pressure regulators, improper
electrical supply and failure to ground, spider webs in burners, intake and exhaust air blockage of
vents, broken or damaged wiring harnesses, or blown fuses can cause hard lock outs. Before
replacing components in furnace, insure the above items are within the specifications. The above
listed items are not a warranty issue or defect in unit.
(Connector E)
Voltage Potential
37-105 VAC
(Connector A) Omron Electronic Pressure Switch
8.0mm WC" ON
(Connector G) Safety Circuit:
(Connector H) Negative Co-efficient Thermistor
50ºF=65KΩ 68ºF=39KΩ
(Connector H)
(Connector C1)
Rinnai Direct Vent Service Manual
Variable 100VAC Motor 60 Hz
Read resistance
100-120 Ω
2.8mm WC" OFF
86ºF=23KΩ
RHFE-201FA
Pin Numbers
Pin #1-2
5 VDC
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