508134-01
Issue 2045
Page 14 of 56
Primary Limit Control (Figure 6)
Primary limit (S10) used on A93DF1E / 92G1DFE units
is located in the heating vestibule panel. When excess
heat is sensed in the heat exchanger, the limit will open.
Once the limit opens, the furnace control energizes the
supply air blower and de-energizes the gas valve. The
limit automatically resets when unit temperature returns to
normal. The switch is factory set and cannot be adjusted.
For limit replacement remove wires from limit terminals,
remove mounting screws, rotate limit switch 90 degrees
and slowly remove from the vestibule panel. Install
replacement limit with same care. See flash code 7 in
Table 4 or Table 5 for troubleshooting if limit switch opens
during operation.
Figure 6. Primary Limit Location and Heat Exchanger
Install limit face down
Gas Valve (Figure 7)
The A93DF1E / 92G1DFE uses an internally redundant
valve to assure safety shut-off. If the gas valve must be
replaced, the same type valve must be used.
24VAC terminals and gas control switch are located on top
of the valve. All terminals on the gas valve are connected to
wires from the ignition control. 24V applied to the terminals
opens the valve.
Inlet and outlet pressure taps are located on the valve. A
manifold adjustment screw is also located on the valve. An
LP/Propane changeover kit is available.
Figure 7. Gas Valve
GAS VALVE SHOWN IN ON POSITION
MANIFOLD
PRESSURE
OUTLET
PORT
INLET
PRESSURE
PORT
MANIFOLD PRESSURE
ADJUSTMENT SCREW
(under barbed fitting)
To Measure Flame Signal - Integrated Control:
Use a digital readout meter capable of reading DC
microamps. See Figure 8 for flame signal check.
1.
Set the meter to the DC amps scale.
2.
Turn off supply voltage to control.
3.
Remove sensor wire from integrated control.
4.
Connect (-) lead to flame sensor wire.
5.
Connect (+) lead to Terminal FS on integrated control.
6.
Turn supply voltage on and close thermostat contacts
to cycle system.
7. When main burners are in operation for two minutes,
take reading.
