Carrier 48HC D17 Series Service And Maintenance Instructions page 47

8. Adjust high- - stage pressure to specified setting by
turning the plastic adjustment screw clockwise to
increase pressure, counter- - clockwise to decrease
pressure.
9. Set room thermostat to call for low- - stage heat. Adjust
low- - stage pressure to specified setting.
10. Replace regulator cover screw(s) when finished.
11. With burner access panel removed, observe unit
heating operation in both high stage and low stage
operation. Observe burner flames to see if they are
blue in appearance, and that the flames are
approximately the same for each burner.
12. Turn off unit, close manual gas shut off valve, remove
pressure manometer and replace the 1/8 in. pipe
fitting on the gas manifold. See Fig. 56.
Burner Ignition
Unit is equipped with a direct spark ignition 100% lockout
system. Integrated Gas Unit Controller (IGC) is located in
the control box. See Fig. 57. The IGC contains a
self- - diagnostic LED (light- - emitting diode). A single LED
(see Fig. 61) on the IGC provides a visual display of
operational or sequential problems 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 11 for an explanation of LED error code
descriptions.
IMPORTANT: Refer to Troubleshooting Tables 16 and
17 for additional information.
LEGEND
LED --- Light Emitting Diode
* A 3 – second pause exists between LED error code flashes. If
If lockout occurs, unit can 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 the Carrier
Replacement Components Division (RCD). See Table 12
for available orifice sizes. See Table 14 for orifice sizes
for Natural Gas and LP fuel usage at various elevations
above sea level. Never drill or plug orifices for operation.
Check that each replacement orifice is tight at its threads
into the manifold pipe and that orifice projection does not
exceed maximum value. See Fig. 54.
IGNITER AND SENSOR LOCATIONS
(BRACKET HEAT COVER NOT SHOWN FOR CLARIY
9 CELL
50HE400026
0.18" (4.60 mm)
NOTE: SPARK GAP MUST BE AT
THE BOTTOM OF THE BURNER.
Fig. 59 - - Typical MRT Spark Adjustment
47
Table 11 – LED Error Code Description*
LED INDICATION
ON
OFF
2 Flashes
3 Flashes
4 Flashes 4 Consecutive Limit Switch Faults
5 Flashes Ignition Lockout Fault
6 Flashes Induced --- Draft Motor Fault
7 Flashes
8 Flashes Internal Control Fault
9 Flashes
more than one error code exists, all applicable codes will be
displayed in numerical sequence.
0.12 - 0.14"
(3.05 - 3.56 mm)
SPARK GAP
ERROR CODE
DESCRIPTION
Normal Operation
Hardware Failure
Limit Switch Fault
Flame Sense Fault
Rollout Switch Fault
Software Lockout
C12546