Carrier 48JC04-06, Service And Maintenance Instructions

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GAS VALVE
All models (except Low NOx) are equipped with 2-stage gas
valves. All Low NOx models are equipped with single-stage gas
valves. See Fig. 51 for locations of adjustment screws and features
on the gas valves.
To adjust gas valve pressure settings:
CHECK UNIT OPERATION AND MAKE NECESSARY
ADJUSTMENTS
NOTE: Gas supply pressure at gas valve inlet must be within
specified ranges for fuel type and unit size. See Tables 9 and 10.
1. Slide out burner partition panel.
2. Remove manifold pressure tap plug from manifold and
connect pressure gage or manometer. (See Fig. 48.)
3. Turn on electrical supply.
4. Turn on unit main gas valve.
5. Set room thermostat to call for heat. If unit has two-stage
gas valve, verify high-stage heat operation before attempt -
ing to adjust manifold pressure.
6. When main burners ignite, check all fittings, manifold,
and orifices for leaks.
7. Adjust high-stage pressure to specified setting by turning
the plastic adjustment screw clockwise to increase pres -
sure, counter-clockwise to decrease pressure.
8. For two-stage gas valves, set room thermostat to call for low-
stage heat. Adjust low-stage pressure to specified setting.
9. Replace regulator cover screw(s) when finished.
10. Observe unit heating operation in both high stage and low
stage operation if so equipped. Observe burner flames to
see if they are blue in appearance, and that the flames are
approximately the same for each burner.
11. Turn off unit, remove pressure manometer and replace the
manifold pressure tap plug. (See Fig. 48.)
LIMIT SWITCH
Remove blower access panel. Limit switch is located on the
fan deck. See Fig. 42.
Burner Ignition
Unit is equipped with a direct spark ignition 100% lockout sys -
tem. The Integrated Gas Unit Controller (IGC) is located in the
control box (see Fig. 49). The IGC contains a self-diagnostic
LED (light-emitting diode). A single LED (see Fig. 52) on the
IGC provides a visual display of operational or sequential prob -
lems when the power supply is uninterrupted. When a break in
power occurs, the IGC will be reset (resulting in a loss of fault
history) and the indoor (evaporator) fan ON/OFF times will be
reset. The LED error code can be observed through the viewport.
During servicing, refer to the label on the control box cover or
Table 9 for an explanation of LED error code descriptions.
If lockout occurs, unit may be reset by interrupting power supply
to unit for at least 5 seconds.
Orifice Replacement
This unit uses orifice type LH32RFnnn (where “nnn” indicates
orifice reference size). When replacing unit orifices, order the
necessary parts through RCD. See the High Altitude Gas Con -
version Kit Gas Heating/Electric Cooling 3 to 15 Ton Small
Rooftop Units Accessory LP (Liquid Propane) Installation In -
structions for details.
Ensure each replacement orifice is tight as its threads into the
manifold pipe and the orifice projection does not exceed maxi -
mum value. See Fig. 46.
Fig. 51 — Typical Gas Valves
IMPORTANT: Leak check all gas connections including
the main service connection, gas valve, gas spuds, and
manifold pipe plug. All leaks must be repaired before
firing unit.
Table 9 — LED Error Code Descriptions*
LED INDICATION ERROR CODE DESCRIPTION
ON Normal Operation
OFF Hardware Failure
1 Flash† Evaporator Fan On/Off Delay Modified
2 Flashes Limit Switch Fault
3 Flashes Flame Sense Fault
4 Flashes 4 Consecutive Limit Switch Faults
5 Flashes Ignition Lockout Fault
6 Flashes Induced-Draft Motor Fault
7 Flashes Rollout Switch Fault
8 Flashes Internal Control Fault
9 Flashes Software Lockout
LEGEND
LED —
Light Emitting Diode
* A 3-second pause exists between LED error code flashes. If more
than one error code exists, all applicable codes will be displayed in
numerical sequence.
† Indicates a code that is not an error. The unit will continue to operate
when this code is displayed.
IMPORTANT: Refer to Tables 10 and 11 for additional
troubleshooting information.
PLA S TIC ADJU S T
S CREW
PLA S TIC ADJU S T
S CREW (2)
REGULATOR S PRING
(PROPANE - WHITE
NATURAL -
S ILVER)
REGULATOR S PRING (2)
(PROPANE - WHITE
NATURAL -
S ILVER)
GA S PRE SS URE
REGULATOR
ADJU
S TMENT
LOW S TAGE
GA S PRE SS URE
REGULATOR
ADJU
S TMENT
MANIFOLD
PRE
SS URE TAP
MANIFOLD
PRE
SS URE TAP
NPT OUTLET
NPT OUTLET
INLET
PRE SS URE TAP
INLET
PRE SS URE TAP
ON/OFF
S WITCH
ON/OFF
S WITCH
REGULATOR
COVER
S CREW
REGULATOR
COVER
S CREW (2)
NPT INLET
NPT INLET
2 S TAGE S INGLE S TAGE