Excavator Heater/Air Conditioner System
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| Illustration 1 | g01077954 |
Illustration 1 shows an illustration of the 300 Series Excavator Heater/Air Conditioner System.
The compressor, the condenser and the accumulator are located in the engine compartment behind the cab. The in-line dryer is located beneath the floor at the front of the cab. The evaporator (not shown) is located inside the heater/air conditioner unit. The heater/air conditioner unit is located in the cab behind the operator's seat.
The heater (not shown) is located inside the heater/air conditioner unit. The water valve and the water valve actuator are attached to the left side of the heater/air conditioner unit.
The electronic control module (ECM) is attached to the front of the heater/air conditioner unit. The inside air sensor is attached to the inside of the cab air inlet on the front of the heater/air conditioner unit. The outside air sensor is attached to the outside air vent at the rear of the cab. The sun light sensor is attached to the front dash panel on the right side of the cab.
Heater/Air Conditioner System
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| Illustration 2 | g01077954 |
Illustration 2 shows a diagram of the Heater/Air Conditioner System.
The air conditioning system is divided into two sides when the system is running: A high pressure side and a low pressure side Pressure equalizes on both sides when the air conditioning system is turned off.
The high pressure side begins at the compressor outlet. The compressor sends high temperature high pressure gas refrigerant to the condenser. In the condenser, air from the fan removes the heat from the high temperature high pressure gas refrigerant and condenses the high pressure gas refrigerant into warm high pressure liquid refrigerant. The warm high pressure liquid refrigerant flows through the in-line dryer to the orifice tube.
The low pressure side begins at the outlet of the orifice tube. The restriction in the orifice tube reduces the high pressure liquid to a low pressure liquid. The low pressure liquid flows into the evaporator where the low pressure liquid begins to boil and change into a low pressure gas.
The boiling refrigerant cools the air that is flowing through the evaporator. The cool low pressure gas that is mixed with a small amount of liquid refrigerant flows to the accumulator. The accumulator separates the liquid refrigerant from the gas refrigerant. The accumulator allows the gas refrigerant to flow to the compressor. The liquid refrigerant continues to boil in the accumulator. The liquid refrigerant changes into a gas. The gas refrigerant flows to the compressor where the cycle is repeated.
The water valve controls the flow of hot engine water into the heater coil. The heater coil reheats the air from the evaporator to the temperature that is requested by the position of the temperature switch (not shown) on the control panel (not shown).
Heater/Air Conditioner Electronic Control System
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| Illustration 3 | g01077958 |
The Heater/Air Conditioner Electronic Control System controls all heating and air conditioning system operations.
Components of the Heater/Air Conditioner Electronic Control System are:
Outside air temperature sensor - Monitors outside air temperature
Cab air temperature sensor - Monitors cab air temperature
Evaporator temperature sensor - Monitors evaporator temperature
Coolant temperature sensor - Monitors engine coolant temperature
Sunlight sensor - Monitors sunload (heat from sun)
Control panel - Input commands to the ECM
Heater/air conditioner ECM - Controls heater/air conditioner system
Under seat air actuator - Opens and closes the under seat air damper
Upper body air actuator - Opens and closes upper body air damper
Outside air actuator - Opens and closes outside air damper
Water valve actuator - Opens and closes water valve
Compressor relay - Start and stop compressor
Blower fan control - Controls blower fan speeds
300B Electronic Controls
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| Illustration 4 | g01077961 |
Illustration 4 shows a Series 300B Excavator air conditioning and heating air box and various electronic components.
The following electronic components are located on the air box:
- (1) Blower fan speed control
- (2) Cab air temperature sensor
- (3) Outside air actuator
- (4) Upper body air actuator
- (5) Water valve
- (6) Water valve actuator
- (7) Electronic control module
- (8) Under seat air actuator
The following electronic components are shown,but the components are not located on the air box:
- (9) Outside (ambient) air temperature sensor
- (10) Sunload sensor
- (11) Control panel
Recently added components:
- (12) Water Temperature Sensor
300B Air Passages
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| Illustration 5 | g01077962 |
Illustration 5 shows the various air passages that are in and out of the air box.
Air enters the air box through the following components: the outside air inlet (2) and the cab air inlet (3) .
Air exits the air box through the following components: upper body air outlet (1), the defrost outlet (4) and the under seat outlet (5) .
300B Heater/Air Conditioner Control Panel
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| Illustration 6 | g01077963 |
When the control panel is in the "ON" mode and the engine start switch is turned to the ON position, the control panel will power the back lighting and turn on all "LED" segments for two seconds.
When the fan increase or decrease switch and/or the temperature increase or decrease switch is held for more than one second, the value will scroll at a rate of 2 steps per second.
Pressing the temperature increase switch, the temperature decrease switch, and the "On/Off" switch simultaneously will toggle the control panel between English and Metric readouts.
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| Illustration 7 | g01077963 |
When the operator depresses an air flow switch, the corresponding indicator light is illuminated.
When either the air upper body, the air under seat, the air upper body/under seat, or the air defrost switch is depressed, a signal is sent to the ECM. The ECM sends power to the upper body actuator and to the under seat actuator. The actuators will open or close the corresponding dampers.
Pressing the air upper body switch opens the upper body air damper and closes the under seat air damper. Air flows through the upper body air vent.
Depressing the air under seat switch opens the under seat air damper and closes the upper body air damper. Air flows through the under seat air vent.
Pressing the air upper body/under seat switch open the upper body air damper and the under seat air damper. Air flows through the upper body and under seat air vents.
Pressing the air defrost switch closes the under seat air damper. Air flow through the upper body vent remains about 20% open in order to defrost/demist the side windows. All remaining air flows through the defrost vent.
When the air outside switch or the air recirculate switch is pressed, a signal is sent to the ECM. The ECM sends power to the outside air actuator. The outside air actuator opens and closes the fresh air and recirculate air damper.
Pressing the air outside switch moves the fresh air and recirculate air damper to close the cab air inlet and open the outside air inlet. Outside air flows into the heater and air conditioner unit.
Pressing the air recirculate switch moves the fresh air and recirculate air damper to close the outside air inlet and open the cab air inlet. Cab air flows into the heater and air conditioner unit.
300B Control Panel - Fan Speed Increase or Decrease Switch
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| Illustration 8 | g01077965 |
Pressing the "FAN SPEED INCREASE" switch or the "FAN SPEED DECREASE" switch sends a signal to the ECM to increase or to decrease the fan speed one step. The fan speed steps are shown on the "FAN SPEED BAR GRAPH".
Pressing and holding either switch will cause the ECM to scroll the fan speed. The scrolling fan speeds are shown on the bar graph. When in the "AUTOMATIC MODE" the fan speed switches override the automatic fan setting.
Pressing and releasing the "TEMPERATURE INCREASE" switch or the "TEMPERATURE DECREASE" switch sends a message to the ECM to increase or decrease the cab temperature setting by 1°F or .5°C. The temperature setting changes are shown on the "TEMPERATURE DISPLAY".
Pressing and holding the "TEMPERATURE INCREASE" switch or the "TEMPERATURE DECREASE" switch sends a message to the ECM to scroll the temperature setting until the switch is released. The temperature setting changes are shown on the "TEMPERATURE DISPLAY".
When a selection switch is pressed, the ECM responds by turning ON the corresponding MODE indicator on the control panel.
300B Control Panel - AUTOMATIC Mode
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| Illustration 9 | g01077966 |
When the EMC is in the "AUTOMATIC" mode, the ECM controls the necessary heater and/or air conditioner output to maintain the desired temperature. The ECM also turns ON the "AUT" indicator on the control panel.
Pressing the "A/C OVERRIDE" switch while in the the automatic mode sends a signal to the ECM for manual control of the air conditioning system. The ECM turns the compressor ON continuously. The ECM turns ON the "A/C override indicator" on the control panel. The A/C override application is used for defogging windows or where extreme humidity is present.
Pressing the "A/C OVERRIDE" switch while in the the A/C override mode sends a signal to the ECM for automatic control of the air conditioning system. The "A/C override indicator" is turned OFF.
300B Heater/Air Conditioner Unit Air Flow
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| Illustration 10 | g01077969 |
Illustration 10 shows the heater/air conditioner unit and the heater/air conditioner unit air flow diagram.
The ECM controls the outside air actuator. The outside air actuator controls the fresh air and the recirculate air damper. When the operator presses the "AIR OUTSIDE" switch, the control panel sends a signal to the ECM. The ECM sends a signal to the outside air actuator. The outside air actuator moves the fresh air and the recirculate air damper which opens the outside air inlet. A mixture of outside air and the recirculate air from the cab flows through the heater/air conditioner unit.
When the operator presses the "AIR RECIRCULATE" switch, the control panel sends a signal to the ECM. The ECM sends a signal to the outside air actuator.
The outside actuator moves the fresh air and threcirculate air damper which opens the cab air inlet and closes the outside air inlet. Only air from the inside of the cab flows through the heater/air conditioner unit.
The blower motor drives the blower which sends air flow through the evaporator and the heater. The evaporator and the heater work together in order to maintain the desired air temperature.
300B and C Upper Body and Under Seat Mode
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| Illustration 11 | g01077973 |
When the operator presses the "AIR UPPER BODY" switch, the control panel sends a signal to the ECM. The ECM sends a signal to the upper body actuator and the under seat actuator. The upper body actuator moves the upper body damper to the OPEN position. The under seat actuator moves the under seat damper to the CLOSE position. Approximately 90 per cent of the air flows through the upper body outlet and 10 per cent flows through the defrost outlet.
When the operator presses the "AIR UNDER SEAT" switch, the control panel sends a signal to the ECM. The ECM sends a signal to the upper body actuator and to the under seat actuator. The upper body actuator moves the upper body damper to the CLOSE position. The under seat actuator moves the under seat damper to the OPEN position. Approximately 90 per cent of the air flows through the under seat outlet and 10 per cent of the air flows through the defrost outlet.
300B and C Upper Body, Under Seat, and Defrost Mode
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| Illustration 12 | g01077975 |
When the operator presses the "AIR UPPER BODY/UNDER SEAT" switch, the control panel sends a signal to the ECM. The ECM sends a signal to the upper body actuator and to the under seat actuator. The upper body actuator moves the upper body damper to the OPEN position. The under seat actuator moves the under seat damper to the OPEN position. Air flows through the upper body, under seat and defrost outlets.
When the operator presses the "AIR DEFROST" switch, the control panel sends a signal to the ECM. The ECM sends a signal to the upper body actuator and to the under seat actuator. The upper body actuator slightly opens the upper body damper and the under seat actuator moves the under seat damper to the CLOSE position. The air flow is approximately 80 percent through the defrost outlet and 20 per cent through the upper body outlet.
300B and C Recirculate Mode
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| Illustration 13 | g01077977 |
When the operator presses the "AIR RECIRCULATE" switch, the control panel sends a signal to the ECM. The ECM sends a signal to the outside air actuator. The outside air actuator moves the fresh air damper and closes the outside air inlet. Only cab air flows through the heater/air conditioner unit. The operator may select the upper body, the under seat, or the defrost to deliver the air into the cab.
DIAGNOSTICS
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| Illustration 14 | g01077978 |
When a problem occurs in the heating and air conditioning system, the control panel will first display a flashing "ERR". Then the control panel will display the number that correspond to the error. For example, the control panel displays a flashing "ERR" followed by a flashing number "032". Checking the Service Manual, you find that this is the service code for an EEPROM Failure of Parameter Memory.
Service codes are found in the Testing and Adjusting Section of the Specifications, Systems Operation, Testing and Adjusting Module for your machine.
300B Sensor Parameters
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| Illustration 15 | g01077979 |
When the ECM is in the "AUTOMATIC" mode, the automatic temperature control unit (ATC) continuously monitors the various sensor inputs. The parameter value of the various sensor inputs may be increased or decreased. However, the ECM must be in the DIAGNOSTIC mode to view or to change the sensors parameter values.
To enter the DIAGNOSTIC mode, simultaneously press the "AUTOMATIC TEMPERATURE CONTROL" switch, the "TEMPERATURE INCREASE" selection switch and the "TEMPERATURE DECREASE" selection switch. The ATC will continue to function normally, however the sensor reading may be read and changed at the control panel.
When in the diagnostic mode, parameters are selected by using the "FAN SPEED INCREASE" switch and the "FAN SPEED DECREASE "switch.
The parameter number "P02" for example, will be briefly displayed. The parameter number will be followed by the current parameter valve "008". In this example, the "P02" is the heater water valve. The "008" indicates the position of the heater water valve (with 0 being fully closed and 15 being fully open).
To return to the "NORMAL" mode, press the ON/OFF switch one time.
300B Control Panel - Self Diagnostics
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| Illustration 16 | g01077980 |
In the self-diagnostics mode, the control panel will direct the mechanic through the diagnostic test.
To enter the self-diagnostic mode, the harness must be unplugged from the control panel. Using jumper wires, follow the procedure as shown in the "Specifications, Systems Operation, Testing and Adjusting Module" for your machine. The control will perform self-diagnostics. After self-diagnostics, the display will show the air upper body selection switch icon. The mechanic must then press the air upper body switch. The control panel will then show another display icon. The mechanic must press the switch for the icon displayed. If the mechanic fails to press the switches in the order that the icons are displayed, the ECM will return the display to the beginning of the test.