Rinnai RHFE-551FA Service Manual page 17

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:
Electronic
Note: Ensure clear and black hose from pressure switch to blower air chamber is not blocked or
crimped with any obstructions including spider webs.
(RT) Room Temperature Control:
Integrated into the PCB program and works in conjunction with the thermistor as noted below.
(TH) Room Thermistor:
Check thermistor by inserting meter leads into each end of thermistor plug. Set your meter to the
200 KΩ scale. Apply heat to the thermistor bulb and the resistance should decrease. Apply cold
and the resistance should increase. Examples of readings:
41ºF=91KΩ
(FR) Flame Rod
Set your meter to read micro-amps (µ). Located on the combustion chamber, the lfame rod proofs
flame for proper operations. A properly grounded electrical supply is a must. Flame rod current
through this rod should range between 4 to 8 icro amps depending on gas type. Low fire flame
current should be 1.2 to 2.0 micro amps.
Improperly setup and /or converted units can soot and cause hard lockouts. If carbon is found on the
flame rod, clean the carbon from it. Then you need to confirm your manifold differential gas pressure on
Hi fire and Lo fire is correct. Insure primary and secondary air dampers are correct. Also, check to ensure
proper orifices were placed in the unit..
IMPORTANT INFORMATION CONCERNING HARD LOCKOUTS:
Other items that can cause hard lockouts are: improper sized gas lines, low gas pressures or pressure drops due
to other appliances on the gas system, spider webs in the burner and air intake of vent system, improper ground
or no ground at receptacle, supply regulators freezing up or defective, voltage drops or bad receptacles, winds in
excess of 40 mph causing turbulence inside the vent terminal, etc.
(OHS1, OHS2, TF) Safety Circuit Check: CN8
Check for continuity reading from pin #1 white wire to pin #5 white wire. If you do not read continuity through this
circuit, locate defective switch and replace that component. Then determine what caused overheat condition.
(MS) Main Switch: CN11
Disconnect CN11 from PCB, being careful not to break wires. Read Blue to Blue, pin #9 and 10 on 40KΩ . When
ON/OFF is in the ON position, you should read 10--18KΩ. When released, you should read open or 0 Ω
Wiring harness, connectors, and fuses should be checked if all above readings are normal.
(Connector CN3)
Voltage Potential
40-105 VAC
(Connector CN13)
0.31 in (8.0 mm) WC
ON
50ºF=65KΩ 68ºF=39KΩ
Rinnai Direct Vent Service Manual
AC Motor 60 Hz, 100VAC
Read resistance
100-120 Ω
Electronic Pressure Switch, 125 V, 0.1 A
0.11 in (2.8 mm) WC
OFF
86ºF=23KΩ
RHFE-263FA
RHFE-263FAII
RHFE-263RFA
Pin Numbers
1-2
5 VDC
17