Carrier 48HJD005-007 specifications Heating, Operating Sequence, Altitude Compensation

NOTE: When the compressor is rotating in the wrong direc- tion, the unit will make an elevated level of noise and will not provide cooling.

Cooling — Set space thermostat to OFF position. To start unit, turn on main power supply. Set system selector switch at COOL position and fan switch at AUTO. position. Adjust ther- mostat to a setting below room temperature. Compressor starts on closure of contactor.

Check unit charge. Refer to Refrigerant Charge section on page 34.

Reset thermostat at a position above room temperature. Compressor will shut off. Evaporator fan will shut off after a 30-second delay.

TO SHUT OFF UNIT — Set system selector switch at OFF position. Resetting thermostat at a position above room tem- perature shuts unit off temporarily until space temperature ex- ceeds thermostat setting. Units are equipped with Cycle- LOC™ protection device. Unit shuts down on any safety trip, and indicator light on thermostat comes on. Check reason for all safety trips.

Compressor restart is accomplished by manual reset at the thermostat by turning the selector switch to OFF and then to ON position.

Main Burners — Main burners are factory set and should require no adjustment.

TO CHECK ignition of main burners and heating controls, move thermostat set point above room temperature and verify that the burners light and evaporator fan is energized. Check heating effect, then lower the thermostat setting below the room temperature and verify that the burners and evaporator fan turn off.

Refer to Table 28 for the correct orifice to use at high altitudes.

Table 28 — Altitude Compensation*

	72,000 AND 115,000		150,000 BTUH
	BTUH NOMINAL
			NOMINAL INPUT
ELEVATION	INPUT
(ft)	Natural	Liquid	Natural	Liquid
	Gas	Propane	Gas	Propane
	Orifice	Orifice	Orifice	Orifice
	Size†	Size†	Size†	Size†
0-2,000	33	43	30	38
2,000	34	43	30	39
3,000	35	44	31	40
4,000	36	44	32	41
5,000	36	44	33	42
6,000	37	45	34	43
7,000	37	45	35	43
8,000	38	46	36	44
9,000	39	47	37	44
10,000	41	48	38	45
11,000	43	48	39	45
12,000	44	49	40	46
13,000	44	49	41	47
14,000	45	50	42	47

*As the height above sea level increases, there is less oxygen per cubic foot of air. Therefore, heat input rate should be reduced at higher altitudes.

†Orifices available through your local Carrier distributor.

Heating

1.Purge gas supply line of air by opening union ahead of the gas valve. If gas odor is detected, tighten union and wait 5 minutes before proceeding.

2.Turn on electrical supply and manual gas valve.

3.Set system switch selector at HEAT position and fan switch at AUTO. or ON position. Set heating temperature lever above room temperature.

4.The induced-draft motor will start.

5.After a call for heating, the main burners should light within 5 seconds. If the burner does not light, then there is a 22-second delay before another 5-second try. If the burner still does not light, the time delay is repeated. If the burner does not light within 15 minutes, there is a lock- out. To reset the control, break the 24 v power to W1.

6.The evaporator-fan motor will turn on 45 seconds after burner ignition.

7.The evaporator-fan motor will turn off in 45 seconds after the thermostat temperature is satisfied.

8.Adjust airflow to obtain a temperature rise within the range specified on the unit nameplate.

NOTE: The default value for the evaporator-fan motor on/off delay is 45 seconds. The Integrated Gas Unit Controller (IGC) modifies this value when abnormal limit switch cycles occur. Based upon unit operating conditions, the on delay can be reduced to 0 seconds and the off delay can be extended to 180 seconds. When one flash of the LED (light-emitting diode) is observed, the evaporator-fan on/off delay has been modified.

If the limit switch trips at the start of the heating cycle dur- ing the evaporator on delay, the time period of the on delay for the next cycle will be 5 seconds less than the time at which the switch tripped. (Example: If the limit switch trips at 30 sec- onds, the evaporator-fan on delay for the next cycle will occur at 25 seconds.) To prevent short-cycling, a 5-second reduction will only occur if a minimum of 10 minutes has elapsed since the last call for heating.

The evaporator-fan off delay can also be modified. Once the call for heating has ended, there is a 10-minute period during which the modification can occur. If the limit switch trips dur- ing this period, the evaporator-fan off delay will increase by 15 seconds. A maximum of 9 trips can occur, extending the evaporator-fan off delay to 180 seconds.

To restore the original default value, reset the power to the unit.

TO SHUT OFF UNIT — Set system selector switch at off po- sition. Resetting heating selector lever below room temperature will temporarily shut unit off until space temperature falls be- low thermostat setting.

Safety Relief — A soft-solder joint at the suction service Schrader port provides pressure relief under abnormal tempera- ture and pressure conditions.

Ventilation (Continuous Fan) — Set fan and system selector switches at ON and OFF positions, respectively. Evaporator fan operates continuously to provide constant air circulation. When the evaporator-fan selector switch is turned to the OFF position, there is a 30-second delay before the fan turns off.

Operating Sequence

COOLING, UNITS WITHOUT ECONOMIZER — When thermostat calls for cooling, terminals G and Y1 and the com- pressor contactor (C) are energized. The indoor (evaporator) fan motor (IFM), compressor, and outdoor (condenser) fan motor (OFM) start. The OFM runs continuously while the unit is in cooling. When the thermostat is satisfied, C is deenergized and the compressor and OFM shut off. After a 30-second delay, the (IFM) shuts off. If the thermostat fan selector switch is in the ON position, the evaporator motor will run continuously.

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