Onan NHC Series Operator's/Service Manual And Parts Catalog page 103

Choke Adjustment: If adjustment of the bimetal is
needed, it must be made at ambient temperature. Do
not attempt adjustments until engine has been shut
down for at least one hour. Loosen the screw which
secures the choke body assembly. Refer to Figure 15.
Rotating the choke body clockwise richens and counter-
clockwise leans the choking effect. For ambient
temperatures above 85 0 F , the choke should be fully
opened. For ambient temperatures below 25 0 F , the
choke should be opened 1/4 inch with the solenoid not
engaged. Tighten the screw that secures the choke
body.
r \\
A e 3 5
0
G 2
\ ^ L O O S E N T H I S
SCREW A N D
' ROTATE T H E
ENTIRE COVER
ASSEMBLY
\ ^ L O O S E N T H I S
SCREW A N D
' ROTATE T H E
ENTIRE COVER
ASSEMBLY
F I G U R E 15. T H E R M O - M A G N E T I C C H O K E
If the choke will not close, check for binding, incorrect
adjustment, or incorrect assembly of the bimetal and
heater assembly. If the choke will not open after the
engine starts, check for . heating. The choke bimetal
should be warm to the touch within a minute or two
after starting.
To disassemble the choke, refer to Figure 16.
If the heater assembly will not heat properly, check
for broken heater wire, high resistance cpnnections
or broken lead wires to the bimetal and heater assem-
bly. With the element at room temperature, check the
heater resistance with an ohmmeter. The resistance
should be about 37.8 to 46.2 ohms for a 12 volt system.
If the heater is defective, replace. There must be
slack in the lead wires between the choke body and
the bimetal and heater assembly. When the start button
is engaged, the solenoid should cause the spring
loaded lever to contact the solenoid core. If this does
not occur, check for broken lead wires or a defective
solenoid core.
The solenoid coil should have a resistance of 2.09 to
2.31 ohms in a 12 volt system.
Assembly: Refer to Figure 16. When assembling the
thermomagnetic choke, connect the bimetal and heater
assembly as follows:
1. Lead tagged G to ground terminal in coil solenoid.
2. Lead tagged H to either of the H I terminals on
the solenoid core..
S P R I N G , C H O K E —i
L E V E R , L I M I T -,
W A S H E R
( 1 7 / 6 4 I . D . X 5 / 8 O . D . X I / i e " )
W A S H E R , I N S U L A T O R
R I N G , R E T A I N I N G
P L A T E , C H O K E
M O U N T I N G
3 0 D Y , C H O K E
A R M A T U R E A S S Y .
P L A T E ,
C H O K E C O V E R
C O I L . S O L E N O I D
F R A M E , S O L E N O I D
/ g v ^ W A S H E R , S H A K E P R O O F
W A S H E R ( 2 4 / 6 4 I . D . X 9 / 1 6 O . D . x l / i e " )
L E A D , G R O U N D
F I G U R E 16. C H O K E A S S E M B L Y
18