Haier GE APPLIANCES NF96US Service Manual page 12

Primary Limit Control (Figure 6)
Primary limit (S10) used on NF96US 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 for troubleshooting
if limit switch opens during operation.
Install limit face down
Figure 6. Primary Limit Location and Heat Exchanger
Gas Valve (Figure 7)
The NF96US 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.
MANIFOLD PRESSURE
ADJUSTMENT SCREW
(under barbed fitting)
INLET
PRESSURE
PORT
GAS VALVE SHOWN IN ON POSITION
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.
Page 12
Figure 7. Gas Valve
MANIFOLD
PRESSURE
OUTLET
PORT
31-5000728 Rev. 0