28 G6RA, G6RK Service Manual
High Limit Controls
The G6 (RA/RK) series incorporates 3 different types of limit
controls: (See Figure 34) a main limit control which is located
in the heat exchanger front panel, a vent limit control located
on the inducer housing, and 1 roll out switch on top of the
burner box on G6RK. G6RA will have one on the left side, one
on the right side, and one on top of the burner box.
All limits are in series with each other and are between #3 and
#8 pins on the nine pin connector that plugs into the control
board. Limit controls are normally closed switches, that open
thermostatically to prevent furnace operation in unsafe
temperature conditions.
Table 6. Status Light Conditions
Figure 34.
Auto
Reset
Manual
Reset
Fault No. Status of Fault
Condition of Flashes Furnace Clearing
No Fault
Limit Circuit open
Pressure Switch
stuck open
Pressure Switch
stuck closed
Ignition Failure
(Unit will try 5 times
for ignition)
Polarity or Ground
False flame or
Gas Valve Relay
Shorted
Power Off
LED on
1
2
3
4
5
Continuous
Flash
LED off
Normal
Main Blower & Induced Draft
Motor running
Induced Draft
Motor running
Unit does not operate
Unit does not operate
Unit does not operate
Both fans operate
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Limit Circuit closes
Pressure Switch closes
Pressure Switch opens
Auto-reset after one hour
Reverse Polarity,
Reestablish Ground
Main Power or Thermostat
resets
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