Fault Finding Chart 3.8 - Rheem 871018 Service Instructions Manual

Fault Finding Chart 3.8

3.8
Fan current detecting
circuit failure
Error code
79 displayed.
Fault Finding Tests 29 – 31
TM031 Integrity 18, 20, 24, 26L Service Instructions REV: B
D.O.I: February 2008
This document is stored and maintained electronically by
Was
Error code 79
displayed prior to
opening the hot
tap?
Test 29 - Diagnostic Point 3
Test 30 and 31 - Diagnostic Point 19
47
Service. All printed copies not bearing this statement in RED are deemed "uncontrolled"
YES
Replace the PCB assembly.
Note: only replace the PCB
NO
assembly if error code 79 is
displayed during combustion.
Components
"Live" when conducting
tests, exercise caution
Conduct test with water flowing
Measure the voltage between 9
Brown and 10 Black on connector
B.
Voltage should be between DC2 –
5V
Test 30
Isolate
conducting resistance
test.
Unplug connector L from the PCB
and measure
between 6 Orange and 12 Orange.
Resistance should be between
0.6kilo-ohms and 2.8kilo-ohms
Test 31
Components
"Live" when conducting
tests, exercise caution
Conduct test with water flowing
Measure the voltage between 6
Orange and
connector L.
Voltage should be between DC70 –
110V
2
will be
power when
the resistance
.
will be
12 Orange on