Carrier 48FK User Manual

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Summary of Contents:

[Page 1] Carrier 48FK

Controls Operation, and Troubleshooting CONTENTS Page SAFETY CONSIDERATIONS .....................2 GENERAL ...................................2-13 Rooftop Information ............................2 VAV Control System ...........................2 Proce...

[Page 2] Carrier 48FK

CONTENTS (cont) Page • CODES 59 AND 60: LOW-PRESSURE SWITCH • CODES 63 AND 64: OIL PRESSURE SWITCH • CODE 70: ILLEGAL UNIT CONFIGURATION • CODES 71 TO 76: THERMISTOR/RESISTOR FAILURE • CODE 81: RESET THERMISTOR OR POTENTIOMETER FAILURE • ...

[Page 3] Carrier 48FK

Several temperature inputs are connected to the proces- sor. There are either 4 or 5 thermistors (depending on the field-installed accessories) which input temperature data into the processor through pin terminal connector J1. See Table 1 and Fig. 2...

[Page 4] Carrier 48FK

Table 2 — Pin Terminal Connector J2 Status Switch Inputs CONNECTOR J2 TERMINAL NO. STATUS SWITCH UNIT SIZE 034-104 1,2 Oil Pressure, Circuit 2 Jumpered 3,4 Oil Pressure, Circuit 1 Jumpered 7,8 Loss Of Charge, Circuit 2 LPS2 9,10 Loss of Charge, Cir...

[Page 5] Carrier 48FK

The potentiometer locations and functions are as follows: P1 — SUPPLY-AIR SET POINT — This potentiometer is located on the display board. The supply-air set point is the cooling mode control temperature which the VAV control system will attempt t...

[Page 6] Carrier 48FK

Table 3 — Output Pin and Terminal Assignments OUTPUT PIN- TERMINAL NAME RATING DEVICE J6-1 Stage 1 Compressor Relay (K1)* 24 vac CR1 J6-2 Stage 2 Compressor Relay (K2)* U2** J6-3 Stage 3 Compressor Relay (K3)* U1 J6-4 Stage 4 Compressor Relay (K4)�...

[Page 7] Carrier 48FK

Compressor Operation CONTROL RELAY (CR) — This relay provides informa- tion to the processor about compressor operation (one con- trol relay per compressor). The relay controls and protects the compressor and also controls the crankcase heater. A c...

[Page 8] Carrier 48FK

GAS SECTION HORIZONTAL SUPPLY SECTION (48FK,JK ONLY) (50FY,JY ONLY) AND EXTENDED PLENUM SECTION (50FKX,FKY,JKX,JKY) Fig. 7 — Thermistor T1 Location, 48FK,JK, 50FY,JY and 50FKX,FKY,JKX,JKY 034-048 Units FAN DISCHARGE/ELECTRIC HEAT SECTION Fig. 8 —...

[Page 9] Carrier 48FK

GAS SECTION HORIZONTAL DISCHARGE SECTION (50FY,JY) (48FK,JK) AND EXTENDED PLENUM SECTION (50FKX,FKY,JKX,JKY) Fig. 9 — Thermistor T1 Location, 48FK,JK, 50JY and 50JKX,JKY 054-074 Units and 50FKX,FKY and 50FY054-104 Units FAN DISCHARGE/ELECTRIC HEAT ...

[Page 10] Carrier 48FK

Economizer — Economizer control is used to control the outside and return air dampers of the unit, to satisfy space cooling demand using all outside air (when permitted), and to satisfy cooling in conjunction with compressor operation (when conditi...

[Page 11] Carrier 48FK

054 UNITS 064, 074, 078 UNITS 088, 104 UNITS Fig. 14 — Thermistor T3 and T4 Locations, Size 054-104 Units 11 ...

[Page 12] Carrier 48FK

Variable Frequency Drive (VFD) — The optional VFD is used to modulate supply fan airflow to maintain duct static pressure on VAV applications. The VFD is located in the supply fan section (see Fig. 18 and 19), and can be ac- cessed by opening the ...

[Page 13] Carrier 48FK

capacity stages to maintain user-established supply-air set point temperature. When VAV units are also equipped with optional supply duct pressure controls (either inlet guide vanes [IGV] or variable frequency drive package), the unit also senses an ...

[Page 14] Carrier 48FK

Fig. 20 — Unit Control Box Arrangement, Sizes 034-048 14 ...

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Fig. 21 — Unit Control Box Arrangement, Sizes 054-078 15 ...

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Fig. 22 — Unit Control Box Arrangement, Sizes 088 and 104 16 ...

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EXAMPLE: T10 desired set point is 70 F. T10 R from Table 4 for 70 F is 5929 ohms. P7 R = 13,084 – 5929 P7 R = 7155 ohms Using an ohmmeter, set the P7 potentiometer to 7155 ohms to achieve a reset initiation set point of 70 F. Potentiometer P3 — R...

[Page 18] Carrier 48FK

Demand Limit — The demand limit function provides a means to limit the cooling capacity of the VAV unit using an external discrete switch function. When enabled by the closure of the external switch, the control will limit the avail- able compresso...

[Page 19] Carrier 48FK

Connect the potentiometer end terminals to terminals 8 and 9 on control terminal block TB3 (sizes 034-048) or TB4 (sizes 054-104) (see Fig 27). Connect the switch terminals to the potentiometer wiper arm terminal and to terminal 10 on TB3 or TB4. To ...

[Page 20] Carrier 48FK

OCCUPIED/UNOCCUPIED — The unit control system will initiate normal occupied mode functions (including Morn- ing Warm-up, Economizer Minimum Position, and Cooling Cycle) whenever a contact closure is made that emulates the normal timeclock contacts....

[Page 21] Carrier 48FK

EXTERNAL ALARM SIGNAL — The unit controls pro- vide an external alarm status signal via a 115-vac output sig- nal at the relay board J5, available at TB2-4 and TB2-5 (common). This signal can be forwarded to the BMS by add- ing a signal relay at th...

[Page 22] Carrier 48FK

INSTALLATION — To enable one or more of the possible smoke control modes available with these units, determine the switches required for the desired mode(s) from Table 6, field-supply and install the appropriate switches and field wire per Fig. 3...

[Page 23] Carrier 48FK

Table 7 — Switch Functions SWITCH NUMBER CONFIGURATION VOLTAGE FUNCTION SW-1 N.C. 115 Deenergize 115-v (OFC, Comp, IFC, Electric Heaters) SW-2 N.C. 115 Deenergize TRAN7 (Process Board) SW-3 N.O. 24 Energize EOR (Open Economizer Outside Air Dampers)...

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VIO NC NO C WHT REMOVED FROM C-DPS SW-8 SW-7 ALL UNITS DPS GRA REMOVE JUMPER 034-048 UNITS 5 6 TB2TB2 SW-1 1 2 TB2TB2 SW-2 REMOVE JUMPER 8 9 TB2TB2 SW-5 REMOVE JUMPER TB3 SW-3 TB3 1 5 TB2 TB2 5 9 SW-4 TB2 SW-6 TB2 5 8 TB3 TB3 SW-9A 3 4 TB4 TB4 SW-9A ...

[Page 25] Carrier 48FK

MODULATING POWER EXHAUST — The tubing for the building pressure control (achieved via the Modulating Power Exhaust option) should sample building pressure in the area near the entrance lobby (or other appropriate and sensitive location) so that loc...

[Page 26] Carrier 48FK

Table 9 — Potentiometer Inputs and Ranges POTENTIOMETER DESCRIPTION LOCATION CONTROL VALID RANGE DEFAULT VALUE P1 Supply Air Set Point Display Board 45 to 70 F 45Fif-22F<P1<45F 70FifP1>70FORIFP1<-22F P2* Economizer Position Economizer M...

[Page 27] Carrier 48FK

DIP SWITCH NO. 1 — Supply Air Set Point (SASP) Reset Type. Factory setting is OFF. Do not change. DIP SWITCH NO. 2 — SASP Reset Enabled. Factory set- ting is OFF (no SASP reset enabled). If SASP reset has been installed, enable it by changing swi...

[Page 28] Carrier 48FK

Supply Fan Control with IGV Option — The inlet guide vane option will modulate the supply fan airflow in order to maintain the static pressure in the supply duct. The set point for duct static pressure is established at the differ- ential pressure...

[Page 29] Carrier 48FK

DETERMINE VFD SET POINT — The unit of measure for the Duct Pressure set point at the VFD is output frequency (Hz), representing the desired DP set point (DPSP) in inches of water gage (in. wg). To convert desired DPSP into the VFD set point, refer ...

[Page 30] Carrier 48FK

Table 13 — VFD Set Point (Frequency Command) for Duct Pressure PRESSURE (in. wg) VFD SET POINT (Hz) CONTROL SIGNAL (mA) PRESSURE (in. wg) VFD SET POINT (Hz) CONTROL SIGNAL (mA) 0.00 0 4.0 2.00 24 10.4 0.25 3 4.8 2.25 27 11.2 0.50 6 5.6 2.50 30 12.0...

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START UNIT To start unit: 1. Close the unit-mounted ON/OFF switch (located in the main control box). 2. Close the field-supplied and -installed timeclock (or con- trol) switch (contacts located at Terminals 1 and 2 (TB3 for 034-048, TB4 for 054-104)...

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Table 15 — Quick Test, Unit Configuration and Switch Check QUICK TEST STEP NO. NORMAL DISPLAY DESCRIPTION CONTROL SWITCH 1. 01 Type Unit — Air-Cooled VAV Configuration Header 2. 2 No. of Compressors Configuration Header 3. 2 1 No. of Unloaders...

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Table 16 — Quick Test, Thermistor and Potentiometer Check QUICK TEST STEP NO. NORMAL DISPLAY DESCRIPTION THERMISTOR OR POTENTIOMETER* 1.4. 1 1 — Thermistor OK 0 — Thermistor Faulty Supply Air Thermistor (T1) 1.5. 1 1 — Thermistor OK 0 — The...

[Page 34] Carrier 48FK

Table 18 — Sensor Resistance Values TEMP (F) RESISTANCE (Ohms) TEMP (F) RESISTANCE (Ohms) TEMP (F) RESISTANCE (Ohms) −60 362,640 45 11,396 150 1,020 −55 297,140 50 9,950 155 929 −50 245,245 55 8,709 160 844 −45 202,841 60 7,642 165 768 −4...

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Operating Sequence — The sequence presented be- low assumes that the unit is equipped with heat for morning warm-up and an economizer. If these items are not enabled with the appropriate DIP switches, the processor bypasses these subroutines. This ...

[Page 36] Carrier 48FK

SIZE 044 UNITS — These units have 2 compressors and 1 unloader on compressor no. 1. See Fig. 42 for compressor and condenser fan motor locations. The unit operating se- quence is as follows: Stage 1 Relays K1 and K3 are energized. Compressor no. 1 ...

[Page 37] Carrier 48FK

074, 078 UNITS 054, 064 UNITS 088, 104 UNITS 054-088 UNITS 104 UNITS Fig. 43 — Component Arrangement, 054-104 Units 37 ...

[Page 38] Carrier 48FK

Supply Fan Control with IGV — In most VAV units, the supply fan static pressure is controlled by inlet guide vanes. The inlet guide vanes operate independently from the micro- processor. The supply static pressure is controlled by a dif- ferential ...

[Page 39] Carrier 48FK

Fig. 44 — Modulating Power Exhaust Component Locations; Sizes 034-048 39 ...

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Fig. 45 — Modulating Power Exhaust Component Locations; Sizes 054-104 40 ...

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Fig. 46 — Modulating Power Exhaust Return End Sheet Metal Skin Detail; Sizes 034-048 Fig. 47 — Modulating Power Exhaust Return End Sheet Metal Skin Detail; Sizes 054-104 41 ...

[Page 42] Carrier 48FK

Table 19 — Compressor Loading and Unloading Sequences COOLING STAGE SIZE 034 UNITS Lead Circuit Lag Circuit Active Cylinders Percent Capacity Comp 1 Unloader U1 Unloader U2 Comp 2 0 OFF OFF OFF OFF 0 0 1 ON ON ON OFF 2 17 2 ON ON OFF OFF 4 33 3 ON ...

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Table 19 — Compressor Loading and Unloading Sequences (cont) COOLING STAGE SIZE 054 UNITS Lead Circuit Lag Circuit Active Cylinders Percent Capacity Comp 1 Unloader U1 Unloader U2 Comp 2 0 OFF OFF OFF OFF 0 0 1 ON ON ON OFF 2 20 2 ON ON OFF OFF 4 4...

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TROUBLESHOOTING By using the display module, actual operating conditions of the unit are displayed while it is running. The Quick Test function allows proper operation of compressors, compres- sor unloaders, fans, and other components to be checked w...

[Page 45] Carrier 48FK

Diagnostic Codes — Diagnostic codes are warnings of abnormal or fault conditions, and may cause either one circuit or the whole unit to shut down. They are assigned code numbers as described below. Table 22 contains a description of each diagnostic...

[Page 46] Carrier 48FK

CODES 59 AND 60: LOW-PRESSURE SWITCH — These codes are used to indicate a low-pressure switch failure. The processor monitors the low-pressure switch. If the switch opens, either by low refrigerant charge, circuit failure, or wir- ing error, the ci...

[Page 47] Carrier 48FK

Incorrect Potentiometer Setting — A potentiometer turned fully clockwise or counterclockwise is outside the valid range and will result in a failure. Faulty Wiring — If the wiring between the potentiometer and the processor board is incorrect, a ...

[Page 48] Carrier 48FK

These 2 steps will help determine if a component other than a board is at fault or if the problem is external to control circuit. A volt-ohmmeter will be needed to troubleshoot boards.A digital meter is preferred but a Simpson 260 or equivalent will ...

[Page 49] Carrier 48FK

Step 5 — Check Relay Board Outputs from the Processor Board — This step involves checking the output signals from relays K1-K3 on the relay board. 1. Turn power to OFF position. 2. Connect negative test probe to TP19 (meter still set to dc). 3. T...

[Page 50] Carrier 48FK

Table 24 — Pin Terminal Connector J1 Voltages PIN TERMINAL VOLTAGE (vdc ± 0.25 v) 1 2 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 0 5 Step 9 − Thermistor Input Connector Checkout 1. Turn power to OFF position. 2. ...

[Page 51] Carrier 48FK

Table 27 — Terminal Strip J5 Connector Resistance Reading QUICK TEST STEP NO. J5 PIN NUMBERS 12345 1. to 2.5. ````0 2.6 00``0 2.7. 0 ` 0 ` 0 2.8. 0 `` 00 2.9. to 3.3. 0 ```0 LEGEND ` — Infinity Step 2 — Check the Display LEDs 1. Enter Quick Te...

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Economizer Motor — All control of the motor (i.e., enthalpy changeover, minimum position control and mixed air control) is accomplished from the main unit microproces- sor through a relay board. Service and installation instruc- tions for the unit ...

[Page 53] Carrier 48FK

Table 29 — Carrier Default Program Parameter Values PARAMETER GROUP PARAMETER DEFAULT VALUE SEtP (Setup) ACC1 60.0 Sec DEC1 60.0 Sec UL 60.0 Hz LL 10.0 Hz* Luln 1 P3 20% F-P3 0.0 Hz P4 100% F-P4 60 Hz tHr1 See Table 31 StC1 0 StL1 110% OLN 1 tYP 5*...

[Page 54] Carrier 48FK

VFD Operation — When troubleshooting the VFD, check first that all required conditions for VFD operation are satisfied. For the VFD to run, the following conditions must be met at the VFD: 1. Drive enable jumper is installed from terminals CC-ST ...

[Page 55] Carrier 48FK

LEGEND AND NOTES FOR FIG. 55 ALM — Alarm C—Contactor CB — Circuit Breaker CCB — Control Circuit Breaker COMP — Compressor CH — Crankcase Heater CR — Control Relay DPS — Differential Pressure Switch DPT — Discharge Pressure Transduce...

[Page 56] Carrier 48FK

Fig. 55 — Typical Wiring Schematic; 48FK,JK and 50FK,FY,JK,JY Units (054-074 Shown) 56 ...

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Fig. 55 — Typical Wiring Schematic; 48FK,JK and 50FK,FY,JK,JY Units (054-074 Shown) (cont) 57 ...

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SERVICE TRAINING Packaged Service Training programs are an excellent way to increase your knowledge of the equip- ment discussed in this manual, including: • Unit Familiarization • Installation Overview • Maintenance • Operating Sequence A la...

[Page 59] Carrier 48FK

START-UP CHECKLIST MODEL NO.: DATE: SERIAL NO.: TECHNICIAN: I. PRE-START-UP: M VERIFY THAT UNIT IS LEVEL M VERIFY THAT ALL PACKING MATERIALS HAVE BEEN REMOVED FROM UNIT M LOOSEN ALL SHIPPING HOLDDOWN BOLTS AND REMOVE SHIPPING BRACKETS PER INSTRUCTION...

[Page 60] Carrier 48FK

III. START-UP CHECK EVAPORATOR FAN SPEED AND RECORD. CHECK CONDENSER FAN SPEED AND RECORD. AFTER AT LEAST 10 MINUTES RUNNING TIME, RECORD THE FOLLOWING MEASUREMENTS: COMP A1 COMP A2 COMP B1 COMP B2 OIL PRESSURE SUCTION PRESSURE SUCTION LINE TEMP DISC...