Carrier 48LC Series Service And Maintenance Instructions page 24

Table 6 – Liquid Propane Supply Line Pressure Ranges
UNIT MODEL UNIT SIZE
48LCD/E/S/R* 04, 05, 06
48LCF/T*
05, 06
(High Heat units only)
Manifold pressure for LP fuel use must be adjusted to
specified range. Follow instructions in the accessory kit to
make initial readjustment.
Table 7 – Liquid Propane Manifold Pressure Ranges
UNIT MODEL UNIT SIZE
48LCD/E/S/R* 04, 05, 06
48LCF/T*
05, 06
(High Heat units only)
Supply Pressure Switch — The LP conversion kit includes
a supply low pressure switch. The switch contacts (from
terminal C to terminal NO) will open the gas valve power
whenever the supply line pressure drops below the
setpoint. See Fig. 32 and Fig. 33. If the low pressure
remains open for 15 minutes during a call for heat, the
IGC circuit will initiate a Ignition Fault (5 flashes)
lockout. Reset of the low pressure switch is automatic on
rise in supply line pressure. Reset of the IGC requires a
recycle of unit power after the low pressure switch has
closed.
Fig. 32 - - LP Low Pressure Switch (Installed)
LP LPS
IGC
BRN
C
J2-11
IGC
J2-12
TSTAT
W2
PNK
Fig. 33 - - LP Supply Line Low Pressure Switch Wiring
MIN MAX
11.0 in. wg 13.0 in. wg
(2740 Pa) (3240 Pa)
11.0 in. wg 13.0 in. wg
(2740 Pa) (3240 Pa)
HIGH FIRE LOW FIRE
10.0 in. wg 5.0in. Wg
(2490 Pa) (1245 Pa)
10.0 in. wg 5.0in. Wg
(2490 Pa) (1245 Pa)
C08238
BRN
NO
C
MGV
GRA
C08285
This switch also prevents operation when the propane tank
level is low which can result in gas with a high
concentration of impurities, additives, and residues that
have settled to the bottom of the tank. Operation under
these conditions can cause harm to the heat exchanger
system. Contact your fuel supplier if this condition is
suspected.
Flue Gas Passageways
To inspect the flue collector box and upper areas of the
heat exchanger:
1. Remove the combustion blower wheel and motor as-
sembly according to directions in Combustion- - Air
Blower section. See Fig. 34.
2. Remove the flue cover to inspect the heat exchanger.
3. Clean all surfaces as required using a wire brush.
Combustion- - Air Blower
Clean periodically to assure proper airflow and heating
efficiency. Inspect blower
periodically during heating season. For the first heating
season, inspect blower wheel bi- - monthly to determine
proper cleaning frequency.
To access burner section, slide the sliding burner partition
out of the unit.
To inspect blower wheel, shine a flashlight into draft hood
opening. If cleaning is required, remove motor and wheel
as follows:
1. Slide burner access panel out.
2. Remove the 7 screws that attach induced- - draft motor
housing to vestibule plate. (See Fig. 34.)
3. The blower wheel can be cleaned at this point. If ad-
ditional cleaning is required, continue with Steps 4
and 5.
4. To remove blower from the motor shaft, remove 2
setscrews.
5. To remove motor, remove the 4 screws that hold the
motor to mounting plate. Remove the motor cooling
fan by removing one setscrew. Then remove nuts that
hold motor to mounting plate.
6. To reinstall, reverse the procedure outlined above.
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wheel every fall and