Service and Parts Manual (2016, 2017, 2018, 2014, 2015, 2013, 2012)
Table Of Contents
- INTRODUCTION
- IMPORTANT SAFETY INFORMATION
- PERSONAL INJURY OR DEATH HAZARDS
- Operation of Equipment in During Construction
- Equipment Identification
- Model and Serial Number Location
- Model and Serial Number information is found on the Manufacturer’s DATA TAG, located on the front or top.
- Model Number Reference Guide
- SERIAL NUMBER REFERENCE GUIDE
- Chassis Specifications
- Small Chassis Dimensions
- Large Chassis Dimensions
- Electrical Data
- Electrical Requirements
- Electrical Ratings Table
- Supply Air Flow and Data
- ELECTRONIC CONTROL BOARD FEATURES
- Electronic Sequence of Operation
- Interface Connector Definitions
- Remote Wall Thermostat
- Remote Wall Thermostat Location
- Desk Control
- Auxiliary Fan Control
- Unit Heat Control Operation - Heat Pump With Electric Heat
- Refrigeration Sequence Of Operation
- Remove The Chassis
- Servicing / Chassis Quick Changeouts
- To Remove the Chassis from the Closet:
- Refrigerant Charging
- Undercharged Refrigerant Systems
- Overcharged Refrigerant Systems
- Restricted Refrigerant System
- Sealed System Method of Charging/ Repairs
- Checking External Static Pressure
- Explanation of charts
- Indoor Airflow Data
- Ductwork Preparation
- Fresh Air Door
- Checking Approximate Airflow
- Electric Heat Strips
- COMPONENT TESTING
- Hermetic Components Check
- Reversing Valve Description And Operation
- Testing The Reversing Valve Solenoid Coil
- Checking The Reversing Valve
- Touch Test Chart : To Service Reversing Valves
- Compressor Checks
- Compressor Replacement -Special Procedure in Case of Compressor Burnout
- Fan Motor
- Capacitors
- Heating Element and Limit Switch
- Drain Pan Valve
- Thermistor Resistence Values (This Table Applies to All Thermistors)
- Testing the Diagnostic Service Module
- Testing the Electronic Control Board
- ELECTRONIC CONTROL BOARD COMPONENTS IDENTIFICATION AND TESTING
- Error Codes and Alarm Status
- Electrical Troubleshooting Chart - Cooling
- 9K Btu, 12K Btu, & 18K Btu
- 24K Btu
- Electrical Troubleshooting Chart - Heat Pump
- Troubleshooting Chart - Cooling
- 9-18K VEA 208/230V
- 9-18K VHA 208/230V
- 9-18K VHA 265V
- 24K VEA 208/230V 2.5/3.4/5.0
- 24K VEA 208/230V 7.5/10.0
- 24K VHA 208/230V 2.5/3.4/5.0
- 24K VHA 208/230V 7.5/10
- 24K VHA 265V 2.5/3.4/5.0
- 24K VHA 265V 7.5/10.0
- VEA9K, VHA9K, VEA12K, VHA12K, VEA18K Figure 901
- AVAILABLE ACCESSORIES
- Thermostat - Rt6
- Thermostat - Rt6p
- Thermostat - WRT1
- Drain Pan
25 PB
OPERATION
Refrigeration Sequence Of Operation
A good understanding of the basic operation of the refrigeration system is essential for the service technician. Without this
understanding, accurate troubleshooting of refrigeration system problems will be more difcult and time consuming, if not (in
some cases) entirely impossible. The refrigeration system uses four basic principles in its operation which are as follows:
1. “Heat always ows from a warmer body to a cooler body.”
2. “Heat must be added to or removed from a substance before a change in state can occur”
3. “Flow is always from a higher pressure area to a lower pressure area.”
4. “The temperature at which a liquid or gas changes state is dependent upon the pressure.”
The refrigeration cycle begins at the compressor when a demand is received from the thermostat. Starting the compressor
creates a low pressure in the suction line which draws refrigerant gas (vapor) into the compressor. The compressor then
“compresses” this refrigerant vapor, raising its pressure and its (heat intensity) temperature.
The refrigerant leaves the compressor through the discharge line as a hot high pressure gas (vapor). The refrigerant enters the
condenser coil where it gives up some of its heat. The condenser fan moving air across the coil’s nned surface facilitates the
transfer of heat from the refrigerant to the relatively cooler outdoor air.
When a sufcient quantity of heat has been removed from the refrigerant gas (vapor), the refrigerant will “condense” (i.e.
change to a liquid). Once the refrigerant has been condensed (changed) to a liquid it is cooled even further by the air that
continues to ow across the condenser coil.
The design determines at exactly what point (in the condenser) the change of state (i.e. gas to a liquid) takes place. In all cases,
however, the refrigerant must be totally condensed (changed) to a liquid before leaving the condenser coil.
The refrigerant leaves the condenser coil through the liquid line as a warm high pressure liquid. It next will pass through the
refrigerant drier (if equipped). It is the function of the drier to trap any moisture present in the system, contaminants, and large
particulate matter.
The liquid refrigerant next enters the metering device. The metering device is called a capillary tube. The purpose of the
metering device is to “meter” (i.e. control or measure) the quantity of refrigerant entering the evaporator coil.
In the case of the capillary tube this is accomplished (by design) through size (and length) of device, and the pressure difference
present across the device. Since the evaporator coil is under a lower pressure (due to the suction created by the compressor)
than the liquid line, the liquid refrigerant leaves the metering device entering the evaporator coil. As it enters the evaporator
coil, the larger area and lower pressure allows the refrigerant to expand and lower its temperature (heat intensity). This
expansion is often referred to as “boiling” or atomizing. Since the unit’s blower is moving indoor air across the nned surface
of the evaporator coil, the expanding refrigerant absorbs some of that heat. This results in a lowering of the indoor air
temperature, or cooling.
The expansion and absorbing of heat cause the liquid refrigerant to evaporate (i.e. change to a gas). Once the refrigerant has
been evaporated (changed to a gas), it is heated even further by the air that continues to ow across the evaporator coil.
The particular system design determines at exactly what point (in the
evaporator) the change of state (i.e. liquid to a gas) takes place. In all
cases, however, the refrigerant must be totally evaporated (changed)
to a gas before leaving the evaporator coil.
The low pressure (suction) created by the compressor causes the
refrigerant to leave the evaporator through the suction line as a cool
low pressure vapor. The refrigerant then returns to the compressor,
where the cycle is repeated.
Suction
Line
Evaporator
Coil
Metering
Device
Refrigerant
Strainer
Discharge
Line
Condenser
Coil
Compressor
Refrigerant Drier
Liquid
Line