Carrier 48EZ-A Start-Up, Check for Refrigerant Leaks, Unit Sequence of Operation, Burner Assembly

4. Verify the following conditions:

a.Make sure gas line is free of air. Before lighting the unit for the first time, perform the following with the gas valve in the “OFF” position:

NOTE: If the gas supply pipe was not purged before connecting the unit, it will be full of air. It is recommended that the ground joint union be loosened, and the supply line be allowed to purge until the odor of gas is detected. Never purge gas lines into a combustion chamber. Immediately upon detection of gas odor, retighten the union. Allow 5 minutes to elapse, then light unit.

b.Make sure that condenser-fan blade is correctly positioned in fan orifice. Leading edge of condenser-fan blade should be 1/2 in. (12 mm) maximum from fan orifice.

c.Make sure that air filter(s) is in place.

d.Make sure that condensate drain trap is filled with water to ensure proper drainage.

e.Make sure that all tools and miscellaneous loose parts have been removed.

START-UP

Step 1 — Check for Refrigerant Leaks

Proceed as follows to locate and repair a refrigerant leak and to charge the unit:

1.Locate leak and make sure that refrigerant system pressure has been relieved and reclaimed from both high- and low-pressure ports.

2.Repair leak following Refrigerant Service procedures. NOTE: Install a bi-flow filter drier whenever the system has been opened for repair.

3.Add a small charge of R-410A refrigerant vapor to system and leak-test unit.

4.Recover refrigerant from refrigerant system and evacuate to 500 microns if no additional leaks are not found.

5.Charge unit with Puron (R-410A) refrigerant, using an electronic scale. Refer to unit rating plate for required charge.

Step 2 — Unit Sequence of Operation

48EZ-A Sequence of Operation

a. CONTINUOUS FAN

(1.) Thermostat closes circuit R to G energizing the blower motor for continuous fan.

b. COOLING MODE

(1.) If indoor temperature is above temperature set point thermostat closes circuits R to G, R to Y and R to O-The unit delivers cooling airflow.

c.HEAT PUMP HEATING MODE

Outdoor temperature above balance point setpoint of thermostat.

(1.) On a call for heating, terminals “Y” and “G“ of the Hybrid thermostat are energized. The “Y“ signal is sent to the Defrost Board (DB) terminal “Y”. The DB has a built in five minute anti-short cycle timer which will not allow the compressor to restart before the time delay has expired.

(2.) “T2” energizes the compressor contactor via the High Pressure Switch (HPS) and Low Pressure Switch (LPS). The compressor and outdoor fan start. Thermostat “G” energizes the Interface Fan Board terminal “G”. The blower motor is energized through contacts of the IFB.

(3.) When the thermostat removes the “Y” and “G” calls, the compressor contactor and outdoor fan are

de-energized. The evaporator motor is de-ener- gized after a 90 sec. delay.

d.GAS HEATING MODE

Outdoor temperature below balance point setpoint of thermostat.

Heating Sequence of Operation

(See Fig. 15 and 16 and unit wiring label.)
On a call for heating, terminal W of the thermostat is energized,
starting the induced-draft motor. When the pressure switch senses
that the induced-draft motor is moving sufficient combustion air,
the burner sequence begins. This function is performed by the
integrated gas unit controller (IGC). The indoor (evaporator)-fan
motor is energized 45 sec after flame is established. When the
thermostat is satisfied and W is de-energized, the burners stop
firing and the indoor (evaporator) fan motor	shuts off after a
45-sec time-off delay. Please note that the IGC	has the capability
to automatically reduce the indoor fan motor on delay and increase
the indoor fan motor off delay in the event of high duct static
and/or partially-clogged filter.
NOTE: An LED (light-emitting diode) indicator is provided on		A
		--
the control board to monitor operation. The control board is
		48EZ
located by removing the burner access panel (see Fig. 19). During
normal operation, the LED is continuously on.

Step 3 — Start-up Heating and Make Adjust- ments

!CAUTION

UNIT COMPONENT DAMAGE HAZARD

Failure to follow this caution may result in damage to the unit being installed.

Complete the required procedures given in the Pre-Start-Up section before starting the unit. Do not jumper any safety devices when operating the unit.

Complete the required procedures given in the Pre-Start-Up section before starting the unit. Do not jumper any safety devices when operating the unit. Make sure that burner orifices are properly aligned. Unstable operation my occur when the burner orifices in the manifold are misaligned.

Follow the lighting instructions on the heating section operation label (located on the inside of the control access panel) to start the heating section.

NOTE: Make sure that gas supply has been purged, and that all gas piping has been checked for leaks.

Pipe Plug Manifold

A07679

Fig. 11 - Burner Assembly

15