Carrier 50ZH Instruction Manual download pdf (Page 11)

TO USE THE COOLING CHARGING CHART

This method is to be used in cooling mode only. Take the outdoor

ambient temperature and read the suction pressure gauge. Refer to

charts to determine what the suction temperature should be. If

suction temperature is high, add refrigerant. If suction temperature

is low, carefully recover some of the charge. Recheck the suction

pressure as charge is adjusted.

Example: (See Fig. 18)

Outdoor Temperature —85°F

Suction Pressure—74 psig

Suction Temperature should be—60°F

Note—Suction Temperature may vary +/- 5°F.

HEATING MODE CHARGE

Do not attempt to adjust charge by cooling methods while in heat

pump heating mode. Recover refrigerant and weigh in according to

unit data plate refrigerant data.

Step 4—Indoor Airflow and Airflow Adjustments

NOTE: For cooling operation, the recommended airflow is 350 to

450 cfm per each 12,000 Btuh of rated cooling capacity.

Table 4 shows dry coil air delivery for horizontal discharge units.

Tables 5-7 show pressure drops.

NOTE: Be sure that all supply- and return-air grilles are open,

free from obstructions, and adjusted properly.

Disconnect electrical power to the unit and install lockout tag

before changing blower speed. Electrical shock can cause

serious injury or death.

Airflow can be changed by changing the lead connections of the

blower motor.

Units 50ZH 036, 048, and 060 blower motors are factory wired for

low speed operation. Units 50ZH030 and 042 are factory wired for

medium speed operation.

FOR 208/230-V

The motor leads are color-coded as follows:

To change the speed of the indoor fan motor (IFM), remove the fan

motor speed leg lead from the indoor fan relay (IFR) with units

030, 042, 048 & 060 or the time delay relay (TDR) on 036 size and

replace with lead for desired blower motor speed. Insulate the

removed lead to avoid contact with chassis parts.

FOR 460-V MOTORS

The motor leads are color coded as follows:

To change the speed of the indoor fan motor (IFM) from low speed

to high speed, remove the red lead from the indoor-fan relay (IFR).

ON 2–Speed Motors: Insulate the red lead to avoid contact with

any chassis parts. Separate the black lead from the purple lead.

Connect the black lead to the IFR. Insulate the purple lead to avoid

contact with any chassis parts. ON 3–Speed Motors: remove the

fan motor speed leg lead from the indoor (indoor) fan relay (IFR)

and replace with lead for desired blower motor speed.

Step 5—Unit Controls

All compressors have the following internal-protection controls.

HIGH-PRESSURE RELIEF VALVE

This valve opens when the pressure differential between the low

and high side becomes excessive.

LOSS OF CHARGE SWITCH

Located on the outdoor liquid line is a low-pressure switch which

functions as a loss-of-charge switch. This switch contains a

Schrader core depressor. This switch opens at 7 psig and closes at

22 psig. No adjustment is necessary.

COMPRESSOR OVERLOAD

This overload interrupts power to the compressor when either the

current or internal temperature become excessive, and automati-

cally resets when the internal temperature drops to a safe level.

This overload may require up to 60 minutes (or longer) to reset;

therefore, if the internal overload is suspected of being open,

disconnect the electrical power to the unit and check the circuit

through the overload with an ohmmeter or continuity tester.

3-PHASE

CONNECTIONS

TO DISCONNECT

PER NEC

SINGLE-PHASE

CONNECTIONS

TO DISCONNECT

PER NEC

GROUND

LEAD

UNIT GROUND

BLK

YEL

BLU

C00012

Fig. 13—Line Power Connections

THERMOSTAT

AND SUBBASE

UNIT CONTROL POWER

SPLICE BOX

BRN

WHT

YEL

GRN

RED

ORN

C99056

Fig. 14—Control Connections

3-SPEED 2-SPEED

black = high speed black = high speed

blue = medium speed -

red = low speed red = low speed

3-SPEED (060 ONLY) 2-SPEED

black = high speed black = to purple

- yellow = line

orange = medium speed purple = to black

blue = low speed red = line

1 ... 10 11 12 ... 24

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Carrier 50ZH Instruction Manual Page 11

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