Carrier 48HJ20---28 Determine Type of Unit Control, To Light Unit Units with Thermostat Control

!WARNING

ELECTRICAL SHOCK HAZARD

Failure to follow this warning could result in personal injury or death.

Before performing recommended maintenance, be sure main power switch to unit is turned off and lockout tag is installed.

Your combination heating/cooling unit is equipped with direct spark ignition and induced draft power combustion blower.

!WARNING

FIRE, EXPLOSION HAZARD

Failure to follow this warning could result in personal injury, death and/or property damage.

Burners will light automatically. Do not attempt to light by hand.

!WARNING

ELECTRICAL OPERATION HAZARD

Failure to follow this warning could result in personal injury, death, or property damage.

Do not use this unit if any part has been under water. A flood-damaged unit is extremely dangerous. Attempts to use the unit can result in fire or explosion. A qualified service agency should be contacted to inspect the unit and to replace all gas controls, control system parts, electrical parts that have been wet or the furnace if deemed necessary.

IMPORTANT: Always keep the unit’s area clear of combustible materials. Do not obstruct the air openings to the unit. Air is required for combustion and ventilation proper operation. Follow the instructions provided in this book for lighting and shutting down the unit. Should the gas supply fail to shut off or if overheating occurs, shut off the gas valve to the unit before shutting off the electrical supply. The following inspections must be completed post unit installation. The detailed routine maintenance inspections are in the Maintaining Your Unit section.

Post Unit Installation Inspection:

1.All flue and vent connections are clear and free of obstruc- tions, are leak-free and not damaged.

2.Duct connections are leak-free and physically sound.

3.The unit base support is free of cracks, gaps, etc.

4.There are no signs of unit deterioration.

5.Burners are aligned correctly.

6.Follow routine maintenance inspection.

DETERMINE TYPE OF UNIT CONTROL

The procedures used to light or shut off the unit depend on the type of unit control. This section will help determine the control type of the unit.

Electro-Mechanical Control

These units may be controlled directly by a thermostat, or indirectly by a third-party control that connects to the thermostat inputs. For direct thermostat control, use the Electro-Mechanical Control procedures in this book. For units with third-party controls connected to the thermostat inputs, refer to the third-party control instructions for procedures to ensure complete unit shut off.

ComfortLinkt Control

These units have a factory-installed Carrier ComfortLink control. A Scrolling Marquee display is located on the front of the unit control box behind the control box and compressor access door. These units may be controlled directly by a thermostat, directly by a space temperature sensor, or indirectly through other Carrier Comfort Networkr (CCN) communication devices. To ensure complete unit shut off, use the ComfortLink Control procedures in this book.

TO LIGHT UNIT

(UNITS WITH THERMOSTAT CONTROL)

!DANGER

FIRE, EXPLOSION HAZARD

Failure to follow this warning could result in personal injury or death.

1.Do not turn off the electrical power to unit without first turning off the gas supply and apply lockout tags.

2.Before attempting to start the gas heating section, familiarize yourself with all the procedures that must be followed.

3.Never attempt to manually light the burners on the unit with a match, lighter, or any other flame. If the electric sparking device fails to light the burners, refer to the shutdown procedures, then call your dealer as soon as possible.

See Fig. 1 for location of gas valve. Refer to Fig. 2 while proceeding with the following steps.

Step 1 — Set room thermostat to the lowest temperature setting and set SYSTEM switch to OFF position.

Step 2 — Close the external gas pipings manual shut off valve located outside the unit.

Step 3 — Turn off the electrical supply to the unit and install lockout tag.

Step 4 — Remove the heat section access panel.

Step 5 — Turn the Off/On selector switch on the gas valve to the OFF position and wait 5 minutes.

Step 6 — Move the Off/On selector switch on the gas valve to the ON position.

Step 7 — Replace the heat section access panel.

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