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Carrier 024-036 Service Manual Download Page 30

: Service Manual

Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.

30

Sequence of Operation

FAN OPERATION
The FAN switch on the thermostat controls indoor fan operation. When

the FAN switch is placed in the ON position, the indoor (evaporator) fan

motor (IFM)  is energized through the G terminal on the thermostat. The

motor’s internal logic then provides power to the indoor (evaporator) fan

motor (IFM). The IFM will run continuously when the FAN switch is set

to ON.
When the FAN switch is set to AUTO, the thermostat deenergizes the

IFM (provided there is not a call for cooling). The contacts open and the

IFM is deenergized. The IFM will be energized only when there is a call

for cooling, in heat pump heating mode or if the unit is equipped with

accessory  electric  heat,  the  indoor-fan  motor  will  also  run  while  the

accessory electric heat is energized.

NOTE: 

Motors  on  this  product  are  programmed  for  60  second  time

delay on tap 1 and 30 second time delay on tap 2. There is no time delay

on tap 3. The indoor fan will remain ON for the set time delay after G or

W2 is de-energized.
COOLING OPERATION
With a call for cooling (Y), the compressor, outdoor fan, and indoor fan

start  immediately.  When  the  cooling  demand  is  met,  Y  de-energizes,

shutting the compressor, indoor fan and the outdoor fan.
HEATING OPERATION
With a call for heating (Y), the compressor, outdoor fan, and indoor fan

start immediately. If Y cannot satisfy the heating demand, the auxiliary

or  backup  heat  (W2)  energizes.  In  case  of  staged  heating,  W3  is

energized if the demand is not met. When heating demand is met, W3,

W2 and Y sequentially de-energize shutting the compressor, indoor fan

and the outdoor fan. 
CONTINUOUS FAN
With the continuous indoor fan option selected on the thermostat, G is

continuously energized. The continuous fan speed will be the same as

the cooling fan speed.
DEFROST
Defrost board (DB) is a time and temperature control, which includes a

field-selectable time period between checks for defrost (30, 60, 90 and

120 minutes). The time period is factory-set at 60 minutes and should

only be adjusted by a trained service person. Electronic timer and defrost

cycle  start  only  when  contactor  is  energized  and  defrost  thermostat

(DFT) is closed.
Defrost mode is identical to Cooling mode. The outdoor fan motor stops

because of “OF1” and “OF2” contacts opening on the defrost board, a

bank  of  optional  electric  heat  turns  on  to  warm  air  supplying  the

conditioned space.
ELECTRIC RESISTANCE HEATING
If accessory electric heaters are installed, on a call for “Emergency Heat”

the thermostat energizes W which energizes the heater relay and in turn

energizes  the  electric  heaters. The  IFM  is  energized    which  starts  the

indoor-fan motor. If the heaters  are staged, W2 is energized when  the

second  stage  of  heating  is  required.  When  the  need  for  heating  is

satisfied, the heater and IFM are de-energized.

ECM Fan Motor Troubleshooting

Caution – Do not disconnect motor plugs under load.

• Check the  high-voltage  supply  to  motor.   The ECM  fan motor will

always have high voltage to the  motor even when the motor is off.

The 24 volt signal cycles the motor on and off.  The motor can accept

more  than  one  24  volt  control  signal  to  the  different  motor  taps

without damaging it.  The motor will default to the highest speed tap

that see a 24 volt signal.

Fan won’t run...

• Cycle power off to the unit. Disconnect the two plugs going into the

motor.  One plug is the high voltage supply and the other is the low

voltage control.

• Cycle  power  back  on  and measure  the  high  voltage supply  plug  to

determine if there is voltage at plug.  If there is no voltage at plug,

determine if there is power to the unit.  The easiest place to measure

the voltage is on the line side of the contactor.  If there is voltage at the

contactor  and no voltage  at the  plug, cycle  the  power back off  and

inspect the wiring harness and plug for loose or broken connections.

• Replace the wiring harness and plug, if it is found to be defective.

• If  there  is  power  at  the  high  voltage  plug,  check  the  low  voltage

control signal.

• With the power on to the unit, verify that there is 24volts between R

and C in the low voltage control box. If there is not 24 volts at R and C

check the inline 3 amp fuse.  If the fuse is blown, check for shorted,

bare or chaffed wires before installing another fuse in the holder.  If

the fuse is good make sure there is line voltage on the primary side of

the transformer.  Then check the secondary side of the transformer.  If

there is line voltage on the transformer primary and no voltage on the

secondary; replace the transformer.

• If there is 24volts between R and C, jump R and G together in the low

voltage control box.  Check to see if there is a 24 volt signal at pins 1,

2 or 3 referenced to common (ground) at the motor’s low voltage plug.

If there is no voltage between common and one of the pins, trace the

wires back to the low voltage control box.

• If there is power at the high voltage plug, voltage at pins 1, 2 or 3 on

the low voltage plug, the connections are good between the plugs and

motor and the motor is not running: replace the motor.

Two 24 volt signal wires will be connected from the thermostat to the

low  voltage  control  plug.  One  wire  (signal)  will  be  for  constant  fan

(cooling) speed and the other will be for electric heat.
If  there  is  an  intermittent  motor  operation  issue,  check  the  1000  ohm

resistor between the green “G” wire and the brown “C” wire in the unit’s

wiring harness. (See unit’s wiring diagram.) The resistor could be blown

(open). This resistor is in line with the fan motor to provide a load for the

thermostat’s triacs, or relay.

Time Delays

The unit/system time delays include:

• The air conditioning or heat pump units do not have any built in time

delays  to  start  the  cooling  or  heating  cycle.  Most  residential

thermostats  have  an  electronic  safety  start  feature  built  into  the

software to prevent compressor short cycling.

• The indoor fan motor (ECM) has a built in fan off delays on the first

two taps of the motor. The third motor tap will shut off immediately

after the 24v signal is gone. See the following for details:

Tap 1 - 60 second off delay

Tap 2 - 30 second off delay

Tap 3 - 0 second off delay

• The only other timing feature in the heat pump units are built into the

defrost board. See defrost board sequence for more details on defrost

time delays and setups.

Pressure Switches

The  R-410A  air  conditioner  contains  one  pressure  switch  to  prevent

system  operation  of  the  pressures  get  excessively  high.  The  high

pressure switch opens at 650 psig and closes at 420 psig. The pressure

switch  setting  is  considerably  higher  than  on  comparably  sized  R-22

units. The high pressure switch can be identified by their pink stripe on

the switch’s electrical wires.
The R-410A heat pump contains a loss of charge switch in the liquid line

which opens at 20 psig and closes at 45 psig. See troubleshooting section

for sequence when a pressure switch trip occurs.

Summary of Contents for 024-036

Page 1: ...ns Rotating fan blades can cause personal injury Appropriate safety considerations are posted throughout this manual where potentially dangerous techniques are addressed Follow all safety codes Wear safety glasses protective clothing and work gloves Have a fire extinguisher available Read these instructions thoroughly and follow all warnings or cautions included in literature and attached to the u...

Page 2: ... low ambient cooling applications Suggested in all commercial applications 2 Evaporator Freeze Thermostat An SPST temperature actuated switch that stops unit operation when evaporator reaches freeze up conditions Usage Guideline Required when low ambient kit has been added 3 Isolation Relay An SPDT relay which switches the low ambient controller out of the outdoor fan motor circuit when the heat p...

Page 3: ...ls must meet the original equipment specifications Insulation must meet NFPA 90A requirements for flame spread and smoke generation Foam gaskets that are in the conditioned air stream must meet the requirements of UL 94 5VA for flammability Instructions for insulation installation 1 Apply adhesive on non foil side of the insulation 2 Align insulation to the panel 3 Care must be taken while applyin...

Page 4: ... reserves the right to change at any time specifications and designs without notice and without obligations 4 A220851 Fig 3 Unit Base Dimensions Small Medium Cabinet with Full Louver 13 4 SEER2 HEAT PUMP 13 4 SEER2 AIR CONDITIONER ...

Page 5: ... the right to change at any time specifications and designs without notice and without obligations 5 A220853 Fig 4 Unit Base Dimensions Heat Pump Air Conditioner Large Cabinet with Full Slots 13 4 SEER2 HEAT PUMP 13 4 SEER2 AIR CONDITIONER ...

Page 6: ...acturer reserves the right to change at any time specifications and designs without notice and without obligations 6 A220854 Fig 5 13 4 SEER2 Air Conditioner Medium and Large Cabinet with Louvers 13 4 SEER2 Air Conditioner ...

Page 7: ... panel to access components above See Fig 7 3 Access or removal of the condenser coil a Removal of the top the control compressor panel the front left side louver panel b Screws from the compressor compartment and either the side of the unit or below the condenser fan depending on the shape of coil will need to be removed to remove condenser coil See Fig 8 4 Access or removal of the evaporator coi...

Page 8: ...ons 8 Labeling The wiring schematic sub cooling charging tables with instructions and warning labels Refer to Fig 10 for label location A10163 Fig 10 Label Location FIELD CONNECTIONS BLOWER PANEL WIRING DIAGRAM ON BACKSIDE OF CONTROL FRONT OF CONTROL COMPRESSOR PANEL WARNING ADVERTISSMENT WARNING ADVERTISSMENT WARNING ADVERTISSMENT ...

Page 9: ...0k scale Using an analog ohmmeter check each terminal to ground use capacitor case Discard any capacitor which measures 1 2 scale deflection or less Place ohmmeter leads across capacitor and place on R X 10k scale Meter should jump to a low resistance value and slowly climb to higher value Failure of meter to do this indicates an open capacitor If resistance stays at 0 or a low value capacitor is ...

Page 10: ...s or heat pumps R 410A pressure switches are identified by a pink stripe down each wire Low Pressure Switch Neither of the air conditioner or heat pump units have a low pressure switch The heat pump models have a loss of charge switch located downstream of the liquid line filter drier See loss of charge for more details High Pressure Switch AC HP The high pressure switch is located in the discharg...

Page 11: ...at or Off the valve is de energized There is no compressor delay built into this control A05332 Fig 14 Defrost Control Heating Sequence of Operation On a call for heating thermostat makes R Y and R G Circuit R Y sends low voltage through the safeties and energizes the contactor which starts the compressor and energizes the T1 terminal on the circuit board The T1 terminal energizes the defrost logi...

Page 12: ...gations 12 A220832 Fig 15 DFT Sensor Location 024 048 SEE DETAIL B DETAIL SEE DETAIL D DETAIL D SEE DETAIL F DETAIL SEE DETAIL H DETAIL H HIURVW WKHUPRVWDW FDQ HLWKHU EH ORFDWHG RQ WKH ERWWRP RI WXEH DV VKRZQ RU RQ WKH WRS DQG PXVW QRW LQWHUIHUH ZLWK DQ RWKHU WXELQJ 030 036 13 4 SEER2 042 13 4 SEER2 048 13 4 SEER2 024 13 4 SEER2 ...

Page 13: ...Whether the unit is in heating or cooling mode it will run a defrost cycle for 10 minutes each time the compressor has been energized for the selected time interval The board will terminate automatically after 10 minutes of defrost time regardless of defrost thermostat position If defrost thermostat is stuck open The unit will not defrost If unit will not defrost 1 Perform the speedup function as ...

Page 14: ...0 F 10ºC to 70 F 21 1ºC Resistance goes from zero to when contacts are open 8 If either opening or closing temperature does not fall within above ranges or thermostat sticks in 1 position replace thermostat to ensure proper defrost operation NOTE With timing cycle set at 90 minutes unit initiates defrost within approximately 21 sec When you hear the reversing valve changing position remove screwdr...

Page 15: ... manufacturer s performance data 4 A whistling or squealing noise during operation may indicate a partial blockage of the refrigerant charge 5 A whistle on shut down could indicate a partial leak path as refrigerant is equalizing from high to low side On occasion an in line discharge check valve has prevented this sound 6 If a compressor hums but won t start it could indicate either a voltage or a...

Page 16: ... sources of problems have been eliminated compressor must be replaced Because compressor is a sealed unit it is impossible to determine exact mechanical failure However complete system should be checked for abnormalities such as incorrect refrigerant charge restrictions insufficient airflow across indoor or outdoor coil etc which could be contributing to the failure Runs Does Not Pump In this type...

Page 17: ...not run although external electrical and mechanical systems appear normal Compressor must be checked electrically for abnormalities Before troubleshooting compressor motor review this description of compressor motor terminal identification Single Phase Motors To identify terminals C S and R 1 Turn off all unit power 2 Short the run and start capacitors to prevent shock 3 Remove all wires from moto...

Page 18: ...mpressor Removal and Replacement Once it is determined that compressor has failed and the reason established compressor must be replaced 1 Shut off all power to unit 2 Remove and recover all refrigerant from system until pressure gages read zero psig Use all service ports 3 Disconnect electrical plug from compressor Disconnect or remove crankcase heater if equipped and remove compressor holddown n...

Page 19: ...ing or first stage heating for heat pumps O Energizes reversing valve on heat pumps C Common side of transformer G Indoor Fan Ground Circuit To determine if a wire has broken or come in direct contact with shell causing a direct short to ground follow these steps 1 Recover all refrigerant charge 2 Using an ohmmeter on R X 10 000 ohm scale or megohmmeter follow manufacturer s instructions 3 Be sure...

Page 20: ...checked such as frost or condensate water on refrigerant tubes The sound made by a reversing valve as it begins or ends defrost is a whooshing sound as the valve reverses and pressures in system equalize An experienced service technician detects this sound and uses it as a valuable troubleshooting tool Using a remote measuring device check inlet and outlet line temperatures DO NOT touch lines If r...

Page 21: ...tor with liquid refrigerant The bleed hole allows a small amount of oil and refrigerant to enter the return line where velocity of refrigerant returns it to compressor If bleed hole plugs oil is trapped in accumulator and compressor will eventually fail from lack of Table 3 Compressor Information 13 4 SEER2 AC Unit Size 24 30 36 42 48 60 Type Emerson Scroll Emerson Scroll Emerson Scroll LG Scroll ...

Page 22: ...tdown TXVs are specifically designed to operate with R 410A refrigerant use only factory authorized TXV s Do not interchange R 410A and R 22 TXVs TXV Operation The TXV is a metering device that is used in air conditioning and heat pump systems to adjust to changing load conditions by maintaining a preset superheat temperature at the outlet of the evaporator coil The volume of refrigerant metered t...

Page 23: ...ston TXV Number Outdoor Heating Piston Number 13 4 SEER2 24 57 30 63 36 67 42 76 48 80 60 TXV Heat Pump Unit Size ton Indoor Cooling Piston TXV Number Outdoor Heating Piston Number 13 4 SEER2 24 57 30 63 55 36 67 57 42 76 59 48 TXV 60 TXV 70 WARNING PERSONAL INJURYAND ENVIRONMENTAL HAZARD Failure to relieve system pressure could result in personal injury and or death 1 Relieve pressure and recover...

Page 24: ...power to unit 2 Recover refrigerant from system through high flow service valves 3 Break vacuum with nitrogen 4 Remove top cover See Access Compressor or other internal cabinet component Fig 6 Fig 8 5 Remove screws in coil panels 6 Use midget tubing cutter to cut liquid and vapor lines at both sides of coil Cut in convenient location for easy reassembly with copper slip couplings 7 Lift coil verti...

Page 25: ...and assure a tight dry system before charging The 2 methods used to evacuate a system are the deep vacuum method and the triple evacuation method Deep Vacuum Method The deep vacuum method requires a vacuum pump capable of pulling a vacuum of 500 microns and a vacuum gauge capable of accurately measuring this vacuum depth The deep vacuum method is the most positive way of assuring a system is free ...

Page 26: ...ely not controlling properly i e stuck open REPLACE VALVE If superheat is higher than 15 F proceed to Step 3 3 Perform TXV function check With system running place sensing bulb in ice bath for 1 minute superheat should increase If no response Replace Valve If OK proceed to Step 4 4 Check for even temperature distribution at outlet of each circuit of evaporator If greater than 15 F between circuits...

Page 27: ...air return air wet bulb temperature with a sling psychrometer or electronic equivalent 6 Using Superheat Charging Table Table 6 find outdoor temperature and indoor air wet bulb temperature At this intersection note superheat Where a dash appears on table do not attempt to charge unit under these conditions or refrigerant slugging may occur In this situation refrigerant must be evacuated and weighe...

Page 28: ... for Safe Electric Heater Operation Air Conditioner AC Unit Size Minimum Airflow CFM 5 kW 7 5 kW 10 kW 15 kW 20 kW 24 600 750 750 X X 30 600 750 750 X X 36 600 750 750 1050 X 42 600 750 750 1050 X 48 600 750 750 1050 1400 60 600 750 750 1050 1400 Heat Pump HP Unit Size Minimum Airflow CFM 5 kW 7 5 kW 10 kW 15 kW 20 kW 24 750 800 800 X X 30 750 800 800 X X 36 750 800 800 1200 X 42 750 800 800 1200 ...

Page 29: ...12 107 102 97 92 2785 45 42 39 36 33 414 114 109 104 99 94 2854 46 43 40 37 34 424 116 111 106 101 96 2923 47 44 41 38 35 434 118 113 108 103 98 2992 48 45 42 39 36 444 119 114 109 104 99 3061 48 46 43 40 37 454 121 116 111 106 101 3130 49 47 44 41 38 464 123 118 113 108 103 3199 50 48 45 42 39 474 124 119 114 109 104 3268 51 48 46 43 40 484 126 121 116 111 106 3337 52 49 47 44 41 494 127 122 117 ...

Page 30: ...ower off to the unit Disconnect the two plugs going into the motor One plug is the high voltage supply and the other is the low voltage control Cycle power back on and measure the high voltage supply plug to determine if there is voltage at plug If there is no voltage at plug determine if there is power to the unit The easiest place to measure the voltage is on the line side of the contactor If th...

Page 31: ...ntrol panel will expose most of the unit s components Both the air conditioner and heat pump control boxes will be in the upper right corner of the unit There will be a contactor that cycles components off and on The capacitor will assist the outdoor fan and compressor to operate The heat pump models will have a circuit board to control the defrost cycle Always replace these devices with the Facto...

Page 32: ...lectric Heat wiring interconnection electric heater controls removed for clarity Electric Heat Control Box shown uninstalled Electric Heat wiring interconnection electric heater controls removed for clarity Electric Heat Control Box shown uninstalled Air Conditioning Control Box Wiring Heat Pump Control Box Wiring A10030 A10031 HIGH VOLTAGE POWER WIRING ENTRY HOLE LOW VOLTAGE WIRING ENTRY HOLE gro...

Page 33: ...ual Manufacturer reserves the right to change at any time specifications and designs without notice and without obligations 33 A210120 Fig 33 Typical Air Conditioning Single Phase Unit Connection Electrical Diagram ...

Page 34: ...anual Manufacturer reserves the right to change at any time specifications and designs without notice and without obligations 34 A210121 Fig 34 Typical Air Conditioning Single Phase Unit Ladder Electrical Diagram ...

Page 35: ...ervice Manual Manufacturer reserves the right to change at any time specifications and designs without notice and without obligations 35 A210797 Fig 35 Typical Heat Pump Unit Connection Electrical Diagram ...

Page 36: ... Service Manual Manufacturer reserves the right to change at any time specifications and designs without notice and without obligations 36 A210799 Fig 36 Typical Heat Pump Unit Ladder Electrical Diagram ...

Page 37: ...d basepan 5 Reinstall side panel 6 Reconnect electrical power and check for proper operation Cleaning Outdoor Fan Motor and Blade 1 Remove grille fan motor and blade Be careful not to bend or dent fan blade 2 Clean motor and blade with soft brush or cloth Be careful not to disturb balance weights on fan blade 3 Check fan blade setscrew for tightness 4 Reinstall fan motor and blade to grille and ch...

Page 38: ...3 53 5 592 147 9 64 4 58 7 3 13 7 160 56 2 13 4 262 86 9 30 5 364 110 0 43 3 466 128 7 53 7 596 148 4 64 7 60 8 6 13 0 162 57 0 13 9 264 87 4 30 8 366 110 4 43 6 468 129 0 53 9 600 149 0 65 0 62 10 0 12 2 164 57 7 14 3 266 87 9 31 1 368 110 8 43 8 470 129 3 54 1 604 149 5 65 3 64 11 3 11 5 166 58 4 14 7 268 88 4 31 3 370 111 2 44 0 472 129 7 53 2 608 150 1 65 6 66 12 6 10 8 168 59 0 15 0 270 88 9 ...

Page 39: ...TIVE RUN CAPACITOR OUTDOOR FAN STOPPED OR CYCLING ON OVERLOAD OUTDOOR AIR RESTRICTED OR RECIRCULATING RESTRICTED DISCHARGE TUBE OVERCHARGE OR NON CONDENSABLES IN SYSTEM LOW REFRIGERANT CHARGE LINE VOLTAGE TOO HIGH OR LOW DEFECTIVE RUN CAPACITOR COMPRESSOR BEARINGS HIGH SUPERHEAT LOOSE LEAD AT FAN MOTOR MOTOR DEFECTIVE LOW SUCTION PRESSURE DIRTY AIR FILTERS DUCT RESTRICTED DAMPERS PARTLY CLOSED COM...

Page 40: ...OAD CONDITION REVERSING VALVE JAMMED IN MIDPOSITION HIGH SUPERHEAT DEFECTIVE FAN MOTOR CAPACITOR LOOSE LEADS AT FAN MOTOR FAN MOTOR BURNED OUT LOW SUCTION LOW HEAD OUTDOOR FAN STOPPED LOOSE LEADS AT OUTDOOR FAN MOTOR INTERNAL FAN MOTOR KLIXON OPEN FAN MOTOR BURNED OUT DEFROST RELAY N C CONTACTS OPEN ON CIRCUIT BOARD REVERSING VALVE DID NOT SHIFT UNIT NOT PROPERLY CHARGED OUTDOOR FAN RUNNING REVERS...

Page 41: ...R OUTDOOR FAN STOPPED OR CYCLING ON OVERLOAD OUTDOOR AIR RESTRICTED OR RECIRCULATING DAMAGED OR STUCK REVERSING VALVE RESTRICTED DISCHARGE TUBE OVERCHARGE OR NON CONDENSABLES IN SYSTEM LOW REFRIGERANT CHARGE LINE VOLTAGE TOO HIGH OR LOW DEFECTIVE RUN CAPACITOR COMPRESSOR BEARINGS HIGH SUPERHEAT LOOSE LEAD AT FAN MOTOR DEFROST RELAY N C CONTACTS OPEN MOTOR DEFECTIVE LOW SUCTION PRESSURE DIRTY AIR F...

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