Carrier 48HJ015-025 installation instructions Protective Devices

Main Burners Ð For most applications, main burners are factory set and should require no adjustment. However, if burner adjustment is necessary:

1.Perform pilot adjustment.

2.Turn gas valve to ON position. Allow unit to operate at least 15 minutes with burner access panel in place.

3.Remove access panel.

4.Loosen primary air shutter (Fig. 37) and adjust to a mini- mum opening of 5¤8 inch.

5.Retighten primary air shutter and reinstall access panel.

To check ignition of main burners and fan switch opera- tion, move thermostat dial above and below room tempera- ture several times, pausing at least one minute between cycles.

MAIN BURNER REMOVAL

1.Shut off (®eld-supplied) manual main gas valve.

2.Shut off power to unit.

3.Remove unit control box/gas valve access panel, burner section access panel, and center post (Fig. 4 and 5).

4.Disconnect pilot ignitor and pilot proving sensor leads at ICP, rollout switch leads at switch, and pilot tube gas con- nection(s) at the pilot ori®ce.

5.Disconnect gas connection(s) from between gas valve(s) and main burners.

6.Remove 2 screws securing burner assembly to base unit.

7.Slide burner assembly out of unit.

Filter Drier Ð Replace whenever refrigerant system is exposed to atmosphere.

Protective Devices

COMPRESSOR PROTECTION

Overcurrent Ð Each compressor has one manual reset, cali- brated trip, magnetic circuit breaker. Do not bypass connec- tions or increase the size of the circuit breaker to correct trouble. Determine the cause and correct it before resetting the breaker.

Overtemperature Ð Each compressor has an internal pro- tector to protect it against excessively high discharge gas temperatures.

Crankcase HeaterÐ Each compressor has a 125-watt crank- case heater to prevent absorption of liquid refrigerant by oil

in the crankcase when the compressor is idle. Since power for the crankcase heaters is drawn from the unit incoming power, main unit power must be on for the heaters to be energized.

IMPORTANT: After a prolonged shutdown or serv- ice job, energize the crankcase heaters for 24 hours before starting the compressors.

Compressor Lockout Ð If any of the safeties (high-, low- pressure, freeze protection thermostat, compressor internal thermostat) trip, or if there is loss of power to the compres- sors, the cooling lockout (CLO) will lock the compressors off. To reset, manually move the thermostat setting.

EVAPORATOR-FAN MOTOR PROTECTION Ð A manual reset, calibrated trip, magnetic circuit breaker protects against overcurrent. Do not bypass connections or increase the size of the breaker to correct trouble. Determine the cause and correct it before resetting the breaker.

CONDENSER-FAN MOTOR PROTECTION Ð Each condenser-fan motor is internally protected against overtemperature.

HIGH- AND LOW-PRESSURE SWITCHES Ð If either switch trips, or if the compressor overtemperature switch ac- tivates, that refrigerant circuit will be automatically locked out by the CLO. To reset, manually move the thermostat setting.

FREEZE PROTECTION THERMOSTAT (FPT) Ð An FPT is located on the evaporator coil. It detects frost build-up and turns off the compressor, allowing the coil to clear. Once the frost has melted, the compressor can be reenergized by resetting the CLO from the thermostat.

Relief Devices Ð All units have relief devices to pro- tect against damage from excessive pressures (i.e., ®re). These devices protect the high and low side.

Control Circuit, 24-V Ð This control circuit is pro- tected against overcurrent by a 3.2-amp circuit breaker. Breaker can be reset. If it trips, determine cause of trouble before resetting.

Replacement Parts Ð A complete list of replacement parts may be obtained from any Carrier distributor upon request.

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