Paloma PH2-20R OFN Engineering Handbook page 67

Check the resistance across 2 black wires
on bottom Molex:
Refer to Data Table below
Ambient Thermistor Data Table
64DV; 84DV; 95DV: 7K – 23K Ohms
64X; 84X; 95X: 2K – 72K Ohms
H95DV; H95X: 2K – 72K Ohms
SVC 820-Tankless Gas Trouble Shooting Manual
34 – Error Code Diagnostic Chart
Is the resistance
to the Ambient
Thermistor OK?
YES
Remove Molex from Connector "R" at Control Board.
Check continuity from black #3 wire at Molex
connector "R" and black wires at Blue Molex located
behind Control Board. Check continuity from blue #7
wire at Molex connector "R" and blue wire at Blue
Molex located behind Control Board
Is the continuity
across all wires
OK?
YES
Attempt to operate unit again.
If the unit malfunctions due to an Error Code 34:
Replace Control Board
Clean Ambient Thermistor. Retest
Thermistor. IF tests OK, the water heater
appears to be normal. Attempt to operate
NO
unit again. IF resistance NOT OK:
Replace Ambient Thermistor
Replace wiring harness for Connector "R"
on Control Board
NO
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