Operation > Operating Controls
Question:
Please describe the operating controls?
Answer:
The controls and components used in the 52S cooling only or heat/cool units are as follows: the selector switch, the indoor thermostat, the dual capacitor, the temperature limiter, the vent lever, and the fan cycle switch (Figure 45).
FIGURE 45 - TYPICAL 52S UNIT OPERATING CONTROLS
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The selector switch is used to determine the mode of operation: heat, cool, fan, or off. The indoor thermostat controls the room ambient temperature and cycles the heater or the compressor based on the selector switch setting. The dual capacitor aids in the start-up of the compressor and the fan motor. The temperature limiter is mounted on the thermostat under the escutcheon. It is a mechanical device that restricts the amount of rotation of the thermostat. The temperature limiter device may be adjusted by moving the plastic temperature selector tabs to another temperature location on the device. The vent lever is located in the upper right corner of the control box. It is a slide mechanism that opens and closes the vent door. The control may be accessed by removing the front panel of the unit. The fan cycle switch is used to provide 2 options of fan control. The first option, CON, causes the fan to run continuously. The second option, CYC, causes the fan to cycle on when venting, heating, or cooling is requested and off when the thermostat is satisfied.
The 52S heat pump unit contains all the components of the heat/cool and cooling only unit, and the following additional ones: the outdoor frost thermostat and the reversing valve. The outdoor frost thermostat prevents operation of the unit in the heat pump mode when the outdoor coil temperature drops below 15 F, or at about 30 to 35 F outdoor ambient temperature (about 40 to 45 F outdoor ambient temperature for 1999 models). The unit automatically engages the electric heat strip under these conditions.
The outdoor frost thermostat has a manual override to place the unit in electric heat mode operation only. The override switch is located behind the front panel on the right side of the unit control box. Placing the override switch into electric heat mode operation will disable the compressor for ALL heating or cooling operations.
The reversing valve allows for operation in reverse cycle heat pump mode. The valve is located in the piping system and is controlled by the reversing valve solenoid coil. The coil is energized only during the heating mode.
For 52S remote control (RC) units, all controls are located on the wall mounted thermostat except the vent lever and outdoor thermostat. Remote control is a factory-installed option only. There are 2 styles of thermostats qualified for use with 52S series Remote Control units. See Figures 46 and 47. For all other 52S units, room controls are located on the unit or unit control panel. Remote control units do not have a fan cycle switch.
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FIGURE 46 - MANUAL THERMOSTAT
FIGURE 47 - PROGRAMMABLE THERMOSTAT
FIGURE 48 - SAMPLE CONTROL PANELS
FIGURE 49 - CONTROLS LOCATION
DESCRIPTION OF SWITCH SETTINGS
OFF BUTTON
The OFF button terminates unit operation.
FAN ONLY BUTTON
Push button for air circulation without heating or cooling.
HIGH HEAT OR HIGH COOL
Push button and rotate temperature knob to desired comfort level. This function provides maximum heating or cooling, and is recommended to raise or lower the room temperature quickly.
LOW HEAT OR LOW COOL
Push button and rotate the temperature knob to desired comfort level. This function provides minimum heating or cooling with maximum dehumidification. This setting also allows for very quiet fan operation.
FINDING TEMPERATURE SETTING FOR COMFORT LEVEL
Set temperature knob between number 5 and number 6. Push Hi or Low Heat or Cool button and allow unit to run for 15 to 30 minutes. If room is not comfortable, turn knob one number setting at a time. When room is comfortable, keep control knob at that position.
NON-USER ADJUSTABLE SWITCHES
OUTSIDE OR VENT AIR
Push the FAN ONLY button and slide vent lever to OPEN position.
FAN CYCLE
The fan cycle switch allows the fan to operate in 2 modes:
CON - Fan runs continuously, circulating air even when the temperature setting has been satisfied. This helps to maintain the room temperature closer to the thermostat setting. CYC - Fan cycles on and off with the compressor during heating or cooling. Fan stops when the temperature setting is satisfied. This results in longer unit off-time and slightly larger variations in room temperature and humidity.
Units built after the start of 1996 incorporate singlepole, double-throw fan cycle switches that have only 3 terminals. Units built prior to 1996 incorporate a doublepole, double-throw fan cycle switch with 6 terminals and a thermostat bulb heater. The additional terminals control the thermostat bulb heater.
OUTDOOR THERMOSTAT (52SQ Units Only)
The outdoor thermostat has 2 operating modes. The heat pump mode (selector screw set fully clockwise), allows the unit to operate normally in the reverse cycle mode. The electric heat mode (selector screw set fully counterclockwise), disables all compressor operating modes, both heating and cooling.
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SEQUENCE OF OPERATION
HEAT/COOL UNITS (Figure 50)
Fan Mode - With the selector switch set to FAN and the fan switch set to fan cycle, contacts L1 to LO and FCS1 to LS are made.
Cooling (Low) - With the selector switch set to low speed cooling and the fan switch set to fan cycle, contacts FCS2 to LO, COMP to FCS1, and COMP to IT3 are made.
NOTE: The contact in low cooling sequence of operation for FCS2 is MED on units built prior to 1996.
Cooling (High) - With the selector switch set to high speed cool and the fan switch set to fan cycle, contacts FCS2 to HI, COMP to FCS1,and COMP to IT3 are made.
Heating Low - With the selector switch set to low sped the fan switch set to fan cycle, contacts FCS2 to LO, IT1 to LS, L2 to HTR, and FCS1 to LS are made.
NOTE: The contact in low heating sequence of operation for FCS2 is MED on units built prior to 1996.
Heating High - With the selector switch set to high speed heat and the fan switch set to fan cycle, contacts FCS2 to HI, IT1 to LS, L2 to HTR, and FCS1 to LS are made.
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SELECTOR SWITCH CONTACTS, ALL 52SE AA AND CP MODELS
COOLING ONLY UNITS (See table below)
Fan Mode - With the selector switch set to FAN and the fan switch set to fan cycle, contact L1 to LO is made.
Cooling (Low) - With the selector switch set to low speed cooling and the fan switch set to fan cycle, contacts FCS to LO 'and L1 to IT3 are made.
NOTE: The contact in low cooling sequence of operation for FCS2 is MED on units built prior to 1996.
Cooling (High) - With the selector switch set to high speed cool and the fan switch set to fan cycle, contacts FCS to HI, L1 to IT3 are made.
SELECTOR SWITCH CONTACTS, ALL 52SC AA AND CP MODELS
HEAT PUMP UNITS
Fan Mode - With the selector switch set to fan cycle, contacts L1 to LO are made.
Cooling (Low) - With the selector switch set to low cool arid the fan switch set to fan cycle, contacts L1 to IT3 and FCS to LO are made.
NOTE: The contact in low cooling sequence of operation for FCS2 is MED on units built prior to 1996.
Cooling (High) - With the selector switch set to high cool and the fan switch set to fan cycle, contacts L1 to IT3 and FCS to HI are made.
Heating (Low) - With the selector switch set to low heat and the fan switch set to fan cycle, contacts L1 to IT1, FCS to LO and L2 to HTR are made.
Heating (High) - With the selector switch set to high heat and the fan switch set to fan cycle, contacts L1 to IT1, FCS to HI, and L2 to HTR are made.
Defrost Cycle - When heat pump unit is operating in reverse cycle, the outdoor coil may begin to frost. As frost accumulates on the outdoor coil the unit may switch into defrost mode. The defrost mode is activated when the outdoor frost thermostat sensor detects a temperature below 15 F on the coil. At this point, the thermostat de-energizes the compressor and activates the electric heat. The unit will remain in electric heat mode until the outdoor thermostat senses 35 F. The defrost mode is a passive operation and may take some time before the coil defrosts.
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SELECTOR SWITCH CONTACTS, ALL 52SQ AA AND CP MODELS
COMPONENT OPERATION AND TROUBLESHOOTING
Tools needed
VOLT-OHM METER
FLAT AND PHILLIPS SCREW DRIVERS
5/16-IN. NUT DRIVER
SIDE CUTTING PLIERS
WARNING
Before cleaning, servicing, performing maintenance or removing the chassis from the wall sleeve, disconnect all power to the unit to avoid the possibility of electrical shock and personal injury. Only trained and qualified service personnel should perform installation and service procedures on these units. Untrained personnel may perform basic maintenance tasks such as cleaning and replacing filters. Refer to GENERAL DISASSEMBLY section of this manual for proper procedures to disconnect power to 52S units.
The Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Consider the following safety issues:
Prior to performing any service or maintenance on electrical equipment you must Disconnect All Power.
New and unfamiliar tasks should be performed under the supervision of an experienced service technician.
Personal protective equipment, such as safety glasses and work gloves, should be worn.
The floor around the work area should be clean and free of debris.
Make sure tools are the correct tools for job, and that they are working properly and in good condition.
The 52S unit may weigh up to 150 pounds. Use a lifting device or ask for assistance if the unit must be moved.
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INDOOR THERMOSTAT (Heat/Cool and Cool Only Units) (Figure 53)
The thermostat maintains the selected temperature by cycling the compressor on and off during cooling operation and the electric heater during heating operation. The thermostat DOES NOT switch from heating to cooling, or cooling to heating. If the switch is in the CYCLE position, then the fan will be cycled off when the thermostat satisfies. A bulb heater was incorporated on models built prior to 1996 to help provide closer temperature control. This heater does not affect the mechanical operation of the switch.
To verify the operation of the thermostat switch, a continuity test may be performed as follows:
1. Turn off unit power as described in GENERAL DISASSEMBLY section.
2. Remove wire leads from thermostat. Note their locations to ease re-assembly.
3. Place one of the leads of the continuity tester on the terminal marked 2, and the other lead on either the terminal marked 1 or the terminal marked 3.
4. Adjust the thermostat up or down to verify the contacts of the switch open and close. When verifying continuity of a closed switch, the ohm reading should be 0 ohms. An open switch will show OL on the meter.
5. When testing is complete, reconnect the leads.
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FIGURE 53 - INDOOR THERMOSTAT (IT) CONTACTS, ALL 52SE AA AND CP MODELS
FIGURE 54 - INDOOR THERMOSTAT (IT) CONTACTS, ALL 52SQ AA AND CP MODELS
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The heat pump indoor thermostat uses a two-stage switch for the heating mode. The first stage engages the compressor and reversing valve, and the unit operates in normal heat pump mode. The indoor thermostat maintains the selected temperature by cycling the compressor on and off in cooling mode. In the heating mode, the indoor thermostat will cycle the compressor or the heater, depending on the difference between the actual room temperature and the thermostat temperature setting.
When the room temperature is more than 4 F cooler than the indoor thermostat setting, the second heating stage of the indoor thermostat engages the electric heat strip. This design feature allows the user to rapidly warm the room with the electric heat strip by turning the thermostat to its highest setting. When room temperatures approach the desired temperature, the user may adjust the thermostat to a personal comfort setting, which allows for normal heat pump operation.
NOTE: For outdoor temperatures below approximately 35 F (45 F for 1999 models), the outdoor frost thermostat prevents heat pump mode operation and immediately engages the electric heat strip upon a call for heating. The electric heat strip is NEVER energized at the same time as the compressor.
To verify operation of the heat pump indoor thermostat switch, a continuity test may be performed as follows:
1. Turn off unit power as described in GENERAL DISASSEMBLY section.
2. Remove wire leads from thermostat. Note their locations to ease re-assembly.
3. To test stage A, place one lead of the continuity tester on the terminal marked 2, and the other lead on either the terminal marked 1 or the terminal marked 3.
4. Adjust the thermostat up or down to verify the contacts of the switch open and close. When verifying continuity of the closed switch, the reading on the meter should be 0 ohms. An open switch will show OL on the meter.
5. To test stage B contacts, place one lead of the continuity tester on contact 5 and the other lead on either contact 4 or contact 6.
6. Adjust the thermostat up or down to verify the contacts of the switch open and close as in Step 4.
7. When testing is complete, reconnect the leads.
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OUTDOOR FROST THERMOSTAT (Heat Pump Units) (Figure 55)
The Outdoor Frost Thermostat (OFT) is a thermostat that uses a single-pole switch with a manual override selector. The thermostat switches between electric heat and compressor operation when the temperature of the outdoor coil falls below 15 F or rises above 35 F. Switching the override selector to electric heat disables the reverse cycle operation of the thermostat is manually switched to electric heat operation, the compressor is disabled for heating and cooling operations.
To verify the OFT is operational, a continuity test may be performed as follows:
1. Turn off unit power as described in GENERAL DISASSEMBLY section.
2. Remove the leads from the OFT. Note their locations to ease re-assembly.
3. Connect the continuity tester to the switch terminals marked 1 and 2.
4. Rotate the override switch to the electric heat setting and verify that there is continuity between terminals 1 and 2.
5. To check the other contacts, move the lead on terminal 1 to terminal 3. Rotate the override switch to the heat pump setting. There should now be continuity between terminals 2 and 3.
6. Once the test is complete, reconnect the leads.
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FIGURE 55 - OUTDOOR FROST THERMOSTAT (OFT) CONTACTS, ALL 52SQ AA AND CP MODELS
CAPACITOR
The 52S units use a dual capacitor. One part of the capacitor is used with the fan motor. The other part of the capacitor is used by the compressor.
Run circuits on single-phase compressor motors use capacitors which dramatically affect the motor operation. Run capacitors are connected to the motor circuit at all times.
To evaluate the capacitor, perform a visual check first. A shorted capacitor may give a visual indication of its failure. For example, the pop-out hole at the top of a start capacitor may bulge or blow out. A run capacitor may bulge or leak. In these instances, the capacitor must be replaced with one recommended by the manufacturer. If there are no visual signs of capacitor failure, testing of the capacitor resistance may be done with a voltohmmeter as detailed below:
1. Turn off unit power as described in GENERAL DISASSEMBLY section but do not unplug the service cord; it will supply ground connection for the unit chassis. Check to ensure power is off and LOCKED OUT.
2. Connect one lead of a 20,000 ohm, 2-watt resistor to the center group of terminals on the dual capacitor. Attach the other lead from the resistor to an unpainted metal section of the unit chassis. This allows that section of the dual capacitor to discharge. Repeat this process between the other group of terminals.
CAUTION
Capacitors are capable of holding charge similar to a battery and may cause an electrical shock.
1. Locate and disconnect the wires from the start and/or run capacitor to isolate them from the remainder of the circuit. Refer to the unit wiring diagram if you need assistance locating wires.
2. Set up the volt-ohmmeter to measure resistance by connecting the meter across the capacitor terminals. See Figure 56.
3. The reading on the meter should first indicate zero, or a low resistance, then slowly rise toward infinity or some high value or measurable resistance. This indicates the capacitor is most likely good. If the reading goes to zero or a low resistance and stays there, the capacitor is likely shorted and needs replacement. If the reading immediately indicates infinity, the capacitor is likely open and must be replaced.
4. Replace the capacitor if failed and rewire according to the WIRING SCHEMATICS located in the control box of the unit.
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FIGURE 56 - CAPACITOR TEST
FAN CYCLE SWITCH
The fan cycle switch has 2 operating modes, continuous (CON) and cycle (CYC). To verify the fan cycle switch is operational, a continuity test may be performed as follows:
1. Turn off unit power as described in GENERAL DISASSEMBLY section.
2. Label and remove the leads connected to fan cycle switch. See Figure 57.
3. Connect the volt-ohmmeter for 1X ohms and check for continuity from terminal 2 to 1 then change the switch position and check for continuity from terminal 2 to 3. For a 6-terminal switch this test should be done on terminals 5 to 4 and 5 to 6 as well.
4. Once test is complete, reconnect the leads.
FIGURE 57 - FAN CYCLE SWITCH (3 TERMINAL)
ELECTRICAL COMPONENTS REMOVAL AND REPLACEMENT
INDOOR THERMOSTAT
To remove the indoor thermostat, perform the following steps:
1. Turn off unit power as described in GENERAL DISASSEMBLY section.
2. Remove the thermostat knob.
3. Remove control box escutcheon (Figure 58) to expose 2 Phillips head mounting screws. Remove the temperature limiter by gently lifting it off the thermostat knob shaft (Figure 59).
4. Open the control box as described in the GENERAL DISASSEMBLY section of this manual.
5. Remove the thermostat bulb from the clip by gently pressing it down and out of the clip. See Figure 27.
6. Remove the 2 screws mounting the thermostat to the control box.
7. Remove the leads from the indoor thermostat and remove it. Route the capillary out of the control box. Note the wire locations to ease re-assembly.
8. Reverse Steps 1 - 7 to reinstall.
FIGURE 58 - ESCUTCHEON REMOVAL
FIGURE 59 - TEMPERATURE LIMITER
FIGURE 27 - FAN SECTION SCREW LOCATIONS
OUTDOOR FROST THERMOSTAT (Heat Pump Units)
To remove the outdoor frost thermostat (OFT), perform the following steps:
1. Turn off unit power as described in GENERAL DISASSEMBLY section.
2. Remove the 2 screws mounting the thermostat to the right side of the control box.
3. Remove the thermostat capillary from the outdoor coil and clip any wire ties holding the capillary in place.
4. Disconnect the wires and carefully remove the thermostat and capillary from the unit.
5. Reverse Steps 1 - 4 to reinstall.
FIGURE 60 - OUTDOOR FROST THERMOSTAT SCREWS
CAPACITOR
To remove the capacitor, perform the following steps:
1. Turn off unit power as described in GENERAL DISASSEMBLY section.
2. Open the control box (Figure 61) as detailed in the GENERAL DISASSEMBLY section of this manual.
3. Properly discharge the capacitor as described in the Capacitor section under Component Operation and Troubleshooting.
4. Remove the leads to the capacitor. Note the wire locations to ease re-assembly.
5. Close the control box door and remove the screw holding the capacitor.
6. Open the control box door and remove capacitor.
7. Reverse Steps 1 - 6 to reinstall.
FIGURE 61 - COMPONENT LOCATIONS IN OPEN CONTROL BOX
FAN CYCLE SWITCH
The fan cycle switch is located on the right side of the control box. To remove the fan cycle switch, perform the following steps:
1. Turn off unit power as described in GENERAL DISASSEMBLY section.
2. Open the control box as described in GENERAL DISASSEMBLY section of this manual.
3. Remove the 3 wires from the fan cycle switch. See Figure 61 for location.
4. Push the snaps of the switch housing toward the switch with a pair of pliers or small screwdriver. Gently push the switch out of the housing.
5. Reverse Steps 1 - 4 to reinstall.
SELECTOR SWITCH
To remove the selector switch from the unit, perform the following steps:
1. Turn off unit power as described in GENERAL DISASSEMBLY section.
2. Remove thermostat knob and unit escutcheon. See Figure 58.
3. Open control box as described in the GENERAL DISASSEMBLY section of this manual.
4. Remove all the wires to the selector switch. Label wires to simplify re-assembly.
5. Remove the 2 screws mounting the switch and remove switch. See Figure 61.
6. Reverse Steps 1 - 5 to reinstall
FIGURE 58 - ESCUTCHEON REMOVAL
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