Table of Contents Heat Pump Operation Charging Procedure Defrost Board Ohmmeter Capacitor Check (30) Hard Start Kit (31-34) Checking for a Grounded Compressor (35) Unit Orientation (3-4) Cooling Mode (5) Heating Mode (6) Charging Procedure Defrost Board Introduction (36) Determining Proper Charge Req. (37) Using Superheat Chart (38) Using Pressure Curve Chart (39) Using TXV Charging Chart (40-41) Subcooling Charging (42-43) Introduction & Operation (7-11) Test Procedures (12-17) Dual Fuel Kit (15-17) 2 Step Scroll Compressor Refrigeration Cycle Problems Introduction & Bridge Rectifier Circuit (18) Troubleshooting (19-20) Cooling Cycle Problems (44-53) Heating Cycle Problems (54-57) Common Test Procedures Airflow Calculations (21-25) Diagnosing a Seized Compressor (26-28) Single Phase Motor Winding Check (29) Useful Resources Demand Defrost Quick Specs (58-61) R-410A & R-22 Temp./Pressure Chart (62)

Heat Pump Operation Refrigeration Cycle Component Orientation 9 Common Vapor Header Check Valve HPCO Reversing Valve Metering Devices (TEV) Liquid Line Vapor Line Charge Robber Filter Drier 1 8 2 9 2 5 3 4 1 3 5 4 6 6 7 7 8 9

Heat Pump Operation Refrigeration Cycle Component Orientation 1 2 3 4 5 6 Refrigeration Cycle Component Orientation (Later Models) Common Vapor Header Reversing Valve Metering Device (TEV) Liquid Line Vapor Line Filter Drier 1 2 3 4 5 6

Heat Pump Operation Cooling Mode Hot Gas Outdoor Coil Circuits Metering Devices (TEV) Strainer/drier Liquid Line Vapor Line Reversing Valve Common Suction Line Pressure Port Fitting 1 Check Valve 2 5 3 3 4 4 2 3 5 3 6 1 8 7 3 9 6 8 3 7 9 10 10

Heat Pump Operation Heating Mode Reversing Valve Vapor Line Liquid Line Strainer/drier TXV Saturated Low Pressure Common Suction Line Suction Pressure Port Fitting 1 4 Check Valve 2 5 3 4 6 5 6 1 7 8 7 3 8 2 9 9

Reciprocating Compressor Board Scroll Compressor Board Defrost Board Introduction Reciprocating Compressor Models Versus Scroll Compressor Models Reciprocating Compressor Board Scroll Compressor Board vs.

Defrost Board Outdoor Fan Motor Speed Control During Cooling Mode Operation 2 Speed PSC OD Fan Board When the outdoor air temperature is above 78F, the defrost board will run the outdoor fan motor at high speed. When the outdoor air temperature is at 74F plus or minus 5F, the defrost board will operate the outdoor fan at low speed. This feature is used to maintain proper head pressure at cool outdoor air temperatures. Scroll ECM OD Fan Board In heat mode, the outdoor fan is always operated at high speed. The defrost boards used with PSC outdoor fan motors have a relay to switch the fan speeds during cooling mode. ECM outdoor fan motor models have defrost boards that change the Pulse Width Modulation (PWM) voltage to the outdoor fan motor to change the speed from low to high.

Basic Defrost Sequence Defrost Board Basic Defrost Sequence OD Ambient Temp. Sensor Coil Temp. Sensor Board Connections The defrost board has an internal software routine that will compare the outdoor air temperature against the temperature of the outdoor coil. When conditions are reached where the outdoor coil temperature is colder than it should be for the outdoor air temperature, the defrost control will place the system into a defrost mode. The conditions where a defrost cycle is determined to be needed, is a function of the defrost control software routine. These calculated conditions vary with climate conditions.

Defrost Mode Operating Characteristics Initiation Component Operation During Defrost Defrost Cycle Termination The coil termination temperature varies with outdoor air temperatures. When the outdoor air temperature is above 22F, the coil termination temperature is 47F. From 10F-22F, the coil termination temperature is determined by adding 25 degrees to the outdoor air temperature. For example, if the outdoor air temperature is 15F, the defrost coil termination temperature is 25 Plus 15 = 40F.

Defrost Mode Operating Characteristics Diagnostic LED Defrost Control Board Monitors the temperature of the outdoor air and outdoor coil during heating mode and defrost cycle operation. Monitors the time it takes the system to reach defrost termination temperature. If abnormal conditions are detected by the board, A green LED on the defrost board will flash a diagnostic code. Diagnostic codes are generated for heating and defrost cycle faults only. Flash per second: Normal Operation Quick Flashes: The outdoor air temperature and outdoor coil temperature are too close together. Quick Flashes: There are two causes. Cause 1: A defrost cycle terminates on time override instead of termination temperature. Cause 2: The outdoor air temperature and outdoor coil temperature are too far apart. Four Quick Flashes: A multiple of combination faults has occurred. The control will reset if any defrost cycle has terminated with normal temperature conditions or if one of the faults resets on it’s own. Diagnostic LED

DEFROST BOARD - Defrost Mode Operating Characteristics Test Procedures Fig 1 TEST_COMMON PIN FUNCTIONS Jumping the TEST_ Common pin (Fig 1) to the other pins performs the following functions: Speed Up Defrost Cycle Timing (Fig 2) Forcing a Defrost (HEAT PUMP MUST BE RUNNING IN HEAT MODE) (Fig 3) Outdoor Fan Motor Speed Change (Fig 4) Fig 2 Fig 3 Current Models With ECM Outdoor Motor: No Speed Change Function Some heat pump models use an ECM outdoor fan motor that runs at only 1 speed. These motors are energized by 24 volts via the heat pump’s control circuit. The motor is de-energized during the defrost cycle. Fig 4

DEFROST BOARD - Defrost Mode Operating Characteristics Checking for proper voltage to outdoor fan motor (ECM Equipped Models) Voltage Requirements: Single Compressor and 2-Step Compressor Models with ECM Outdoor Fan Motor 2 Stage Duel Compressor High SEER Models (Current production models) 2-Step Unloading Scroll Compressor Models Sensor Checks To determine if the sensors are within calibration range: Step 1: Make sure the outdoor unit is off. Unplug the sensors from the defrost board terminals. Step 2: Measure the air temperature. (Make sure the outdoor coil sensor housing is at the same temperature as the air.) Step 3: Measure the resistance of the thermistors (Fig 1) and compare to the values in the Defrost Board Sensor Table (Fig 2). Fig 1 Fig 2

DEFROST BOARD - Defrost Mode Operating Characteristics Defrost Board Sensor Voltage Check Step 1: Make sure there is 24 volts powering the defrost board. The green LED should be flashing. Step 2: Unplug ambient and coil sensor plugs from the defrost board. Check for 5-6 volts DC at the defrost board sensor pins. (Pins sticking out of the defrost board.) (Across each set of pins.) (Fig 1). If no voltage is read, replace the defrost control board. If voltage is present at the pins, the board is providing power to the temperature sensors. Fig 1 Jumpers J1, J2, and J3 J1: Soft Switchover function may be stopped by cutting the jumper. J2: Is used to set up the board for a Spin fin outdoor coil or plate fin outdoor coil. J3: Is used to set up the board for a reciprocating or scroll compressor. Fig 2

Dual Fuel Kit TAYPLUS103A – Dual Fuel Accessory Used in conjunction with a single or two stage gas furnace, single compressor, dual compressor or two-step heat pump and a multistage mechanical or digital heat pump thermostat. Sequence of Operation - Unrestricted Heating Mode Sequence of Operation - Restricted Heating Mode Sequence of Operation - Cooling Mode

DUAL FUEL KIT - Single Stage Heat Pump/Non-Variable Speed Gas Furnace Un-Restricted Mode

DUAL FUEL KIT - Single Stage Heat Pump/Non-Variable Speed Gas Furnace Restricted Mode

2 Step Scroll Compressor INTRODUCTION The two step scroll is a single speed scroll compressor that has two internal unloading ports. This allows the scroll’s motor to run at one speed, which maintains bearing lubrication and compressor reliability at a higher SEER. The scroll’s internal unloading ports are normally open, or unloading, and are closed when DC power is supplied to an internal AC solenoid. This solenoid has been life tested at 60,000 cycles to simulate over 15 years of service and has an operating range of 18 to 28 volts. The two step scroll was designed to fail in the unloaded position for two reasons. First, if the scroll runs 70 to 80% of the time unloaded, there will be less wear on the component. Second, if the unloading mechanism fails to operate, the end user should notice the capacity loss and call for service. Bridge Rectifier Circuit

2 Step Scroll Compressor (Troubleshooting) Step A 1. Adjust the thermostat for outdoor unit operation calling for 2nd stage. 2. Verify 24 VAC on Y1 & Y2 control wires (Y2 = YL/RD wire & BL common wire)(Fig. 1) and at the Y2 and common terminal of the AC/DC Bridge Rectifier. 3. Measure and record the compressor amperage. Carefully remove the Y2 wire from the Bridge Rectifier terminal and measure the compressor current. Cycle Y2 several more times to verify the solenoid control and slide ring mechanism is operating correctly. If current does not change, proceed to step B. Step B Pull the disconnect to shut off the 220VAC power to the unit. Apply 24 VAC directly to the Y2 Bridge Rectifier terminal and listen for a “click” as the solenoid is energized and the slide ring mechanism shifts. 3. Cycle the Y2 several times to verify the energizing of the solenoid If no “click”, go to step C. Fig 1

2 Step Scroll Compressor (Troubleshooting) Step C 1. Shut off all power to the outdoor unit. (Both 220VAC and 24VAC) and remove the black plug from the side of the compressor containing the fusite plugs to the solenoid coil. 2. Measure ohms (across both fusite pins) the resistance of the solenoid coil that is internally in the compressor (Fig 2). A good solenoid coil should measure 32 to 60 ohms dependent on the compressor temperature. Measure each fusite pin to ground, both should read infinite ohms. Step D 1. With the 220VAC & 24VAC disconnected, reattach the plug to the fusite pins of the internal solenoid. 2. Reapply the 24VAC to the Y2 terminals of the Bridge Rectifier. 3. Set multimeter to DC volts and measure the DC voltage output on the two Bridge Rectifier terminals (+ / -) (Fig 3). The DC voltage reading should be 1.5 to 3 volts lower than the input of 24VAC. The normal operation output range of the Bridge Rectifier should be between 15VDC to 26.5VDC. Fig 2 Fig 3

COMMON TEST PROCEDURES (Airflow Calculations) (Gas Heating Temperature Rise Method) Disconnect power to the furnace. Set the furnace to run its’ indoor blower motor on HIGH SPEED in heat mode operation. Restore power to the furnace. Give the system a Call For Heat and confirm the heating section is running. Establish what the heating capacity of the gas furnace in BTUH Output (clock the meter). Record this value. Run the heating system and allow time for the system temperatures to stabilize. The indoor blower should be on. Measure the temperature of the return air at the furnace filter rack (Fig 1). Record this value. Find a position about 36” away from the supply air plenum and measure the temperature of the supply air at this point (Fig 2). Record this value. Continues… Fig 1 Fig 2

COMMON TEST PROCEDURES (Airflow Calculations) FORMULA: BTUH OUTPUT CFM = 1.08 X Temperature Rise (rT) … Continued 8. Disconnect power to the furnace and place the indoor fan blower motor speed back to its’ original setting for heat mode operation. Subtract your measured return air temperature from your supply air temperature. This is your Delta-T(rT) value. Using your calculator, multiply your rT value by 1.08. Record this value on a piece of paper. Divide your BTUH Output by the value you obtained in Step 11. The answer is your actual system airflow. 120 70 BTUH = 100,000

100,000 BTUH: 100,000 Supply Air Temp: 120F Return Air Temp: 70F FORMULA: 70 BTUH OUTPUT CFM = 1.08 X Temperature Rise (rT) BTUH = 100,000 100,000 BTUH: 100,000 Supply Air Temp: 120F Return Air Temp: 70F j 120F - 70F = 50F (rT) k 1.08 x 50 100,000 l = 1852 CFM 54

COMMON TEST PROCEDURES (Airflow Calculations) PROCEDURE (Single Phase Electric Heat System Temp. Rise Method) With power to the air handler heater section on, Call for Heat. Make sure all heater stages are energized. Measure the supply voltage to the air handler (Fig 1) and record the value. Measure the total amperage being drawn by the air handler. (Fig 2) Record the value. Multiply the measured supply voltage by the measured supply amperage. Now multiply your answer by 3.414. This is your total BTUH Output. Record this value. Once the temperature of the supply air has stabilized, measure the temperature of the supply air 36” from the supply air plenum. Record this value. Measure the temperature of the return air at the air handler filter rack. Record this value. Subtract your return air temperature from your supply air temperature to obtain your Delta-T value. Record this value. Multiply the Delta-T value by 1.08. Record this value. Divide your BTUH Output by the value obtained in step 8. The answer is your actual CFM. Fig 1 Fig 2

60171 j 235Volts x 75Amps x 3.414 = 60171 BTUH Output Air Handler Supply Voltage: 235 Volts Air Handler Section Amperage: 75 Amps Supply Air Temp: 110F Return Air Temp: 74F 110 74 FORMULA: Fig 1 Voltage x Amperage x 3.414 CFM = 1.08 X Temperature Rise (rT) Voltage = 235 Volts Amperage draw = 75 Amps 60171 j 235Volts x 75Amps x 3.414 = 60171 BTUH Output k 110F - 74F = 36F (rT) l 1.08 x 36 60171 m = 1548 CFM 38.88

COMMON TEST PROCEDURES (Diagnosing a Seized Compressor Single-Phase) Determining if a compressor is seized requires that you eliminate all other possible causes before condemning the compressor as seized. Symptoms Electrical problems that could cause a compressor to fail to start will make a compressor act as if it is seized. Low line voltage A pitted set of contactor points A broken wire between the compressor and run capacitor or contactor A failed run capacitor Un-equalized system pressures when the compressor tries to start Before beginning the electrical test sequence, make sure the compressor is not trying to start against Un-equalized system pressures. If it in fact the compressor is trying to start against Un-equalized pressures, check for refrigeration circuit restrictions or short cycling conditions.

COMMON TEST PROCEDURES (Diagnosing a Seized Compressor Single-Phase) Remove power to the outdoor condensing unit. Place an ammeter onto the common motor winding lead of the compressor. (Fig. 2) (Typically the BLACK WIRE coming from the compressor motor terminal cover). Restore power to the condensing unit and call for cooling. Check the ammeter to be sure you are drawing LRA. If the compressor is trying to start, it should hum and then shut off on its’ internal overload. If the compressor does not try to start, the Internal overload may be open. Allow time for it to reset. Once you have confirmed that the compressor is trying to start, proceed to Step 2. Measure the voltage at the compressor contactor while it is under a load. Make sure you have the correct line voltage level at the LOAD SIDE TERMINALS (Fig. 3) of the compressor contactor. Typically this level must not be below or above 10% of the unit nameplate voltage rating. If the line voltage is too low at the LOAD TERMINALS, check the voltage to the LINE TERMINALS (Fig. 4) of the contactor. If the voltage is low at these terminals, there is a problem with the electrical supply to the condensing unit. If the line voltage is normal, but is low at the LOAD TERMINALS, check voltage across the contactor points (Fig. 5.) with the contactor energized. You should measure 0 volts. If you measure voltage across the electrical points of the contactor, there is either pitting or an obstruction at the contactor. Continues… Fig 2 Fig 3 Fig 4

COMMON TEST PROCEDURES (Diagnosing a Seized Compressor Single-Phase) … Continued Correct the problem and then retry starting the compressor. If the voltage level at the contactor is within proper tolerance, continue on to Step 3 Disconnect power to the condensing unit and discharge all capacitors. Remove the wires from the run capacitor (Fig. 6). Using either an ohmmeter or a capacitor tester, check to ensure that the run capacitor is operating properly (see “Testing a Capacitor). If it is not, replace it with one of equal value. If the capacitor is OK, continue on to Step 4. With power to the unit still off, disconnect the wires from the compressor common, run, and start terminals. Perform a motor winding test to check for an open run or start winding. (See “Motor Winding Test”) If either winding is open, replace the compressor. If the windings are OK, proceed to Step 5. Check for a grounded compressor motor. (See “Checking for a Grounded Compressor.”) If any terminal is shorted to ground, replace the compressor. If the motor is not shorted, proceed to Step 6. If everything checks out good electrically, and the compressor is not trying to start against Un-equalized pressures, add a hard start kit (Fig. 7). If the compressor fails to start, replace the compressor. Fig 5 Fig 6 Fig 7

COMMON TEST PROCEDURES (Performing a Single-Phase Motor Winding Test) This test procedure will determine if a PSC compressor motor has failed due to an open motor winding. This test will also detect a possible open Internal Overload. (IOL) Symptoms A compressor with an open winding will fail to start. The compressor may not do anything, or may in fact hum as it tries to start and then trip off on its internal overload. If the IOL is open, the compressor will not try to start. Fig 2 Procedure Remove power to the outdoor condensing unit and discharge all capacitors. Remove the cover from the terminal cover on the compressor and disconnect the wires from the compressor motor Start, Run, and Common terminals. Set your ohmmeter to read very low ohms. Place one ohmmeter lead to the Start Terminal and the other ohmmeter lead to the Common terminal (Fig. 2). Next measure the resistance between the Run terminal and the Common terminal (Fig. 3) To determine if the problem is an open winding or an open IOL, check the resistance between the Run terminal and the Start terminal (Fig. 4). Allow up to four hours for the IOL to re-close. If the IOL does not re-close, replace the compressor. Fig 3 Fig 4

COMMON TEST PROCEDURES (Testing a Run Capacitor With an Ohmmeter) This test procedure will determine if a run capacitor is working properly. Symptoms A compressor with an open run capacitor will fail to start. The motor will attempt to start, hum, and then shut off on its internal overload. (IOL) Fig 1 Procedure Remove power to the condensing unit and discharge all of the capacitors. Check the capacitor for any bulging, open rupture disc, or case damage. Replace the capacitor if these conditions are detected. Remove the wires from the capacitor terminals. Place one ohmmeter lead to each capacitor terminal (Fig. 1). The meter should charge and discharge the capacitor. Your meter will move its needle in response to the capacitor, or if it is a digital meter, the scale will ramp up and down with the charging and discharging state of the capacitor. If the meter does not respond, reverse the meter leads and test again. If the meter still does not respond, replace the capacitor with one of equal value. If the meter does respond, the capacitor is working.

COMMON TEST PROCEDURES (Hard Start Kit) When there is a problem with the hard start circuit, the problem will be either a failed potential relay or a bad start capacitor. Either component failure will result in compressor starting problems. Symptoms Potential Relay Sticks in an open position, Start Capacitor won’t be in the circuit during initial start up. This causes the compressor to have a hard time starting or a failure to start. Sticks in a closed position, Start Capacitor will remain in the circuit during run operation. This causes failure of the start capacitor. Start Capacitor If the start capacitor were defective, the compressor would experience starting problems or in some cases failure to start at all. Tripping of the compressor IOL is possible.

COMMON TEST PROCEDURES (Hard Start Kit) Procedure Checking The Potential Relay SOLEMOID COIL Disconnect power to the unit (Fig. 1) and make sure the Start Capacitor is discharged. Remove the wires from the Potential Relay terminals. Using your OHMMETER check for continuity between the potential relay TERMINALS #2 and #5 (Fig. 2). Do this by placing one meter lead to the #2 TERMINAL and the other meter lead to the #5 TERMINAL. If you read an open circuit, replace the relay. If you measure resistance, the relay coil is OK. (8.5K-15KOHM Typical) FAILURE TO FOLLOW THIS STEP MAY CAUSE INJURY OR DEATH. Fig 1 Fig 2

COMMON TEST PROCEDURES (Hard Start Kit) Procedure Checking The Potential Relay CONTACTS Remove power to the unit (Fig. 3) and make sure the Start Capacitor is discharged. Remove the wires from the Potential Relay terminals. Using your OHMMETER check for continuity between relay TERMINALS #1 and #2 (Fig. 4). You should read 0 OHMS. If you read infinite OHMS, replace the relay. FAILURE TO FOLLOW THIS STEP MAY CAUSE INJURY OR DEATH. Fig 3 Fig 4

COMMON TEST PROCEDURES (Hard Start Kit) Procedure Checking The Start Capacitor With an OHMMETER Remove power to the unit (Fig. 1) and make sure the Start Capacitor is discharged. Visually check the capacitor for a cracked casing, loose terminals, or broken rupture disc in the capacitor top. Replace the capacitor without further tests if these symptoms exist. Set your OHMMETER to the R X 1000 scale. (Zero adjust the meter if necessary) Place one ohmmeter lead to each capacitor terminal (Fig. 2). The meter should charge and discharge the capacitor. Your OHMMETER will either move in response to the capacitor, or if it is a digital meter, the scale will ramp up and down with the charging and discharging of the capacitor. If your meter does not react to the capacitor, reverse the meter leads and try again. If the meter still does not show charging and discharging, replace the capacitor. If the Start Capacitor needs replacing, always replace it with one of equal microfarad rating. The replacement capacitor working voltage should be equal to or greater than the original capacitor. Fig 1 Use a 20,000 OHM resister to discharge the capacitor. DO NOT TOUCH THE CAPACITOR LEADS WITH YOUR HANDS. Fig 2

COMMON TEST PROCEDURES (Checking for a Grounded Compressor) This procedure will determine if a compressor motor is shorted to ground. When the breaker has tripped, NEVER RESET THE BREAKER OR REPLACE THE FUSE WITHOUT CHECKING FOR A GROUNDED COMPRESSOR FIRST. FAILURE TO DO SO MAY RESULT IN INJURY OR DEATH. Fig 1 Fig 3 Ohmmeter Test Procedure Disconnect power to the unit (Fig. 1) and discharge all capacitors. Remove the compressor motor terminal cover and disconnect the wires from the compressor motor terminals. Set your ohmmeter to read the highest resistance scale. Place one meter lead to the common motor terminal and the other lead to the discharge line at the compressor (Fig. 3). You should read either infinite ohms or resistance over 1 million ohms. If you do, that terminal is not grounded. 3. Repeat the procedure for the run and start terminals (Fig. 4). They too should read either infinite ohms or ohms over 1 million. If a lower resistance is read, replace the compressor. Fig 4

CHARGING PROCEDURES (Introduction) Determining Proper Charge Requirements Using the Superheat Chart Measure the outdoor air temperature and the dry bulb and wet bulb temperature of the air inside of the conditioned space. After establishing the indoor and outdoor air temperatures, plot these two measurements on the Superheat Chart.

CHARGING PROCEDURES – Superheat Chart Indoor Air Relative Humidity = 50% Dry bulb Temperature = 85 F Outdoor Air Temperature = 95 F

CHARGING PROCEDURES – FCCV Pressure Curve Chart A- LIQUID PRESSURE B- SUCTION PRESSURE

CHARGING PROCEDURES – Pressure Curve Chart Fig 2 Outdoor Air Temp. = 90F Indoor Wet bulb Temp. = 71F HOW TO USE… Measure the indoor air wet bulb and the outdoor air temperature. Draw a line vertically from 90 degrees vertically onto the liquid pressure curve chart (Fig. 2, A, j). Find where the vertical line intersects 71 degree wet bulb and make a mark (Fig. 2, A, k). From that mark, draw a horizontal line to the left of the chart until it intersects the pressure requirement column (Fig. 2, A, l). Move down to the suction pressure curve (Fig. 2, B) and repeat the process. Adjust your pressure to the chart requirements plus or minus 10PSIG for liquid pressure and plus or minus 3 PSIG for suction pressure.

CHARGING PROCEDURES – TXV Charging Curve Line length = 50’ Lift = 20’

CHARGING PROCEDURES – TXV Charging Curve SERVICE FACTS PRESSURE CURVE Line length = 50’ Lift = 20’ HOW TO USE… Determine which curve to use when determining the required liquid line temperature vs. pressure, a charging curve selection chart is used (Fig. 3). After determining our plot line, refer to the Heat Pump Charging Curve Chart (Figure 4). Measure the liquid pressure and the temperature of the liquid line at the outlet of the condenser coil. Plot a horizontal line then Vertical In All Cases, Maintain liquid pressure or if a heat pump, discharge pressure at the value determined from the SERVICE FACTS PRESSURE CURVE Fig 3 Fig 4

CHARGING PROCEDURES – Subcooling Charging in Cooling Above 55F OD Ambient These charging methods apply to systems with indoor TXVs. Subcooling (in the cooling mode) is the only recommended method of charging above 55F ambient temperatures. For best results - the indoor temperature should be kept between 70F and 80F. Add system heat if needed. At startup, or whenever charge is removed or added, the system must be operated for a minimum 20 minutes to stabilize before accurate measurements can be made. Measure liquid line temperature and refrigerant pressure at service valves. Determine total refrigerant line length, and height (lift) if indoor section is above the condenser. Determine the design subcool temperature from the unit nameplate. Locate this value in the appropriate column of the Subcooling Charging Table. Locate your liquid line temperature in the left column of the table, and the intersecting liquid line pressure under your nameplate subcool value column. Add refrigerant to raise the pressure to match the table, or remove refrigerant to lower the pressure. Again, wait 20 minutes for the system conditions to stabilize before adjusting charge again. 8. When the system is correctly charged, you can refer to System Pressure Curves to verify typical performance.

CHARGING PROCEDURES – Subcooling Charging in Heating Below 55F OD Ambient The subcool charging method in cooling is not recommended below 55F outdoor ambient. The only recommended method of charging at outdoor ambients below 55F, is to weigh in the charge in the heating mode. Use nameplate charge plus standard charge adders for line length. Check liquid line temperature and pressure (at the OD valves) to obtain a minimum of 10F subcooling. Add charge if a minimum of 10F subcooling is not obtained with the nameplate charge plus line length correction. 6. It is important to return in the spring or summer to accurately charge the system in the cooling mode at outdoor ambients above 55F.

COOLING CYCLE PROBLEMS PROBLEM… Reversing valve bypassing hot gas to suction side. Low High Normal L Suction Pressure Liquid Pressure Superheat Subcooling Discharge Pressure X X X X 1 X 2 L H Notes: Point 2 is at least 13F higher than Point 1.

COOLING CYCLE PROBLEMS PROBLEM… Outdoor check valve restricts liquid flow to indoor coil. Low High Normal L Suction Pressure Liquid Pressure Superheat Subcooling Discharge Pressure * X 1 2 X ODTEV X warm X X * warm L L Notes: Significant temperature drop between points 1 and 2. Liquid line pressure lower than discharge gas pressure. Suction vapor superheat high, Liquid line cold. Frosting may occur on the check valve. *Note 1: HP may contain separate check valve allowing refrigerant flow to the indoor coil in cooling mode. *Note2: OD unit may contain an internally checked TEV

COOLING CYCLE PROBLEMS PROBLEM… Indoor metering device restricted Low High Normal L Suction Pressure Liquid Pressure Superheat Subcooling Discharge Pressure X 1 2 X X warm X X warm L L Notes: Restricted metering device will cause low system pressures. Addition of charge will cause high side pressure rise without significant increase in suction pressure. When high side pressure rises, subcooling will also rise.

COOLING CYCLE PROBLEMS PROBLEM… Low indoor air volume Low High Normal L Suction Pressure Liquid Pressure Superheat Subcooling Discharge Pressure X X X cold X X cold L L Notes: All pressures low. Superheat low and subcooling low. TXV models may have hunting TXV. (Fluctuating suction pressure.)

COOLING CYCLE PROBLEMS PROBLEM… Suction line restriction Low High Normal L Suction Pressure Liquid Pressure Superheat Subcooling Discharge Pressure X X X X X 1 X 2 L L Notes: Temperature drop from evaporator suction line (1) connection to the inlet of the reversing valve (2) should not exceed 3F. Check for kink or undersized lineset. Note: R-22 - Each 1 lb drop = 1% capacity loss.

COOLING CYCLE PROBLEMS PROBLEM… Oversized metering device (fixed piston) Low High Normal L Suction Pressure Liquid Pressure Superheat Subcooling Discharge Pressure X X X X X L H Notes: Internal indoor check valve may bypass refrigerant around the metering device. The evaporator will flood and the condenser will starve. Oversized piston will exhibit these symptoms

COOLING CYCLE PROBLEMS PROBLEM… Overcharged (TXV) Low High Normal H Suction Pressure Liquid Pressure Superheat Subcooling Discharge Pressure X X X X X H N Notes: TXV will throttle back refrigerant flow and store the excess charge in the outdoor coil. the suction pressure and suction superheat may appear normal.

COOLING CYCLE PROBLEMS PROBLEM… Overcharged (Fixed Piston) Low High Normal H Suction Pressure Liquid Pressure Superheat Subcooling Discharge Pressure X X X X X H H Notes: The overcharge will flood the evaporator and the condenser. Pressure will be higher than charging chart values. Superheat will be low, subcooling high.

COOLING CYCLE PROBLEMS PROBLEM… Undercharged (TXV) Low High Normal L/N Suction Pressure Liquid Pressure Superheat Subcooling Discharge Pressure X X X X X X X X L L/N Notes: A TXV system with a small undercharge may show normal low side conditions. The outdoor coil will lack refrigerant. Liquid subcooling will be low. Flash gas formation will occur when liquid line pressure drop exceeds available subcooling. A TXV with a significant undercharge will exhibit low suction pressure and high superheat, low head pressure and low subcooling

COOLING CYCLE PROBLEMS PROBLEM… Undercharged (Fixed) Low High Normal L Suction Pressure Liquid Pressure Superheat Subcooling Discharge Pressure X X X X X L L Notes: Both coils will be starved. Superheat will be high and liquid subcooling low. The compressor will be hot.

HEATING CYCLE PROBLEMS PROBLEM… Outdoor check valve stuck open Low High Normal L Suction Pressure Liquid Pressure Superheat Subcooling Discharge Pressure X X X X X L H Notes: Flooded outdoor coil will have high pressure and low superheat. Indoor coil will starve. On models equipped with check valve (see circuits) use a magnet to check for free movement of the check valve internal ball.

HEATING CYCLE PROBLEMS PROBLEM… Reversing valve leaking hot gas into suction line Low High Normal L Suction Pressure Liquid Pressure Superheat Subcooling Discharge Pressure X X X X X 1 2 L H Notes: Reversing valve will have a temperature rise above 13F from suction vapor in (1) to suction vapor out (2).

HEATING CYCLE PROBLEMS PROBLEM… Indoor check valve stuck closed Low High Normal cold L Suction Pressure Liquid Pressure Superheat Subcooling Discharge Pressure X X X X X 1 2 L L Notes: Liquid line will be cold at outlet of indoor coil. Discharge gas pressure may be high if excess charge is in the system.

HEATING CYCLE PROBLEMS PROBLEM… Low indoor airflow Low High Normal hot H Suction Pressure Liquid Pressure Superheat Subcooling Discharge Pressure X X hot X X hot X note note L H Notes: Vapor and liquid lines are hot. If flash gas is present, suction pressure may be low & superheat high.

DEMAND DEFROST QUICK SPECS

DEMAND DEFROST QUICK SPECS

DEMAND DEFROST QUICK SPECS

DEMAND DEFROST QUICK SPECS

R-410A & R-22 T/P CHART