Webasto Storage Cooler Service Manual

Functional Description

• Low refrigerant pressure 1.03 bar ± 0.24 bar (15 psig ± 3 psig)

• The voltage regulator determines that the batteries or alternator are not operating at acceptable levels when the engine is running OR when shore power is being used, shore power is disconnected

• Inverter AC voltage not present

3.3.1.2

Charging Enable/Disable Control

3.3.1.2.1

A charge enable/disable switch mounted on the vehicle dashboard is used for manually enabling/disabling the charging unit for charging the storage cooler assembly. When the switch is in the ON position, the charging unit is enabled and automatic charging of the storage cooler assembly occurs if the conditions

of Section 3.3.1.1.1 are satisfied. When the switch is in the OFF position, the

charging unit is disabled.

3.3.1.2.2

The switch contains one LED indicator which illuminate green when the charging

unit is charging the storage cooler assembly (see Section 3.3.1.1.1 for charging

conditions). This LED indicator will be illuminated only while the compressor is powered on and running.

3.3.1.2.3

The LED indicator turns off when the charging unit stops charging the storage

cooler assembly (see Section 3.3.1.1.3 for stop charging conditions).

Approximate time to completely charge (freeze) the storage core is approximately 6 hours depending on the ambient temperature.

3.4

Discharge Mode

3.4.1

Discharging (Reference Fresh Air and Recirculation State Diagram, Fig. 16 and Cooling Discharge State

Diagram, Fig. 17.)

3.4.1.1

Discharging Modes & Conditions

3.4.1.1.1

A linear voltage blower control is used for air conditioning and ventilation. The blower control is manually operated. NOTE: This blower control does not operate the heater blower since the heater blower is internal to the diesel-fired air heater.

3.4.1.1.2

The maximum blower power draw is set not to exceed 5 amps.

3.4.1.1.3

Blower speed is controlled with a potentiometer knob (S3). When the knob is in the off position, there is no electrical load (including the blower fan and circulating pump).

3.4.1.1.4

Blower control is available when the storage cooler thermostat (TC1) is in the off position for ventilation purposes.

3.4.1.1.5

The fresh air/recirc mode has two settings: fresh air and recirculating (no blending of the two). The fresh air/recirc mode is manually operated via a twoway switch (S5) on the control panel.

3.4.1.1.6

The temperature control is a closed loop which allows for setting the temperature at a comfortable level.

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Functional Description

3.4.1.1.7

Temperature is controlled by a dual potentiometer. One potentiometer controls air conditioning temperature and the other potentiometer controls heating temperature. The required resistance values for the potentiometers are:

• Air Conditioning

Minimum: +20°C = 1000

Ω

Maximum: +26°C = 460

Ω

• Heating

Minimum: +5°C = 150

Ω

Maximum: +35°C = 2150

Ω

For both air conditioning and heating, resistance versus temperature has a linear relation, i.e., middle of temperature range correlates with middle of resistance range.

3.4.1.1.8

For each change in knob position, the temperature increases or decreases in equal amounts throughout the full range of motion for air conditioning and heating.

3.4.1.1.9

A return air temperature sensor is located in the air handling unit which will control when the storage cooler assembly’s circulating pump turns on and off.

3.4.1.1.10

A green LED light is used on the control panel for indicating when the storage cooler assembly circulating pump is running.

3.4.1.1.11

A green/yellow band shown on the control panel above the blue temperature band indicates that when the temperature control is set in the green region of this band, a temperature of 23.9°C (75°F) can be maintained for 8-10 hours of storage cooler duration under the following conditions:

• Outside ambient temperature = 35°C (95°F)

• Sleeper pre-cooled to 23.9°C (75°F)

• Relative humidity = 50%

• No solar loading – e.g. truck parked in a shaded area or run system during the evening

• Airflow to lower and upper bunks

• Recirculated air mode

3.4.1.1.12

A 3-way switch on the control panel is provided for selecting air conditioning mode (top position), heating mode (bottom position), or off mode (middle position). When the switch is set to the off mode, all loads will be off except for those required for the blower and fresh/recirc actuator.

3.4.1.1.13

The 3-way air conditioning/heating selection switch is backlit with a blue LED for air conditioning mode and a red LED for heating mode. The red heating LED also provides diagnostic blinking codes for the diesel-fired air heater.

3.4.1.1.14

Air conditioning selection and air conditioning temperature control is only functional when the blower control (S3) is in the on position.

3.4.2

The relay assembly (located in left side tool box) contains the K2 and K8 relays. The K2 relay is used for controlling turn on of the compressor. The K8 relay is used for determining if inverter AC voltage is

present and will reset the bypass valve if 120 VAC power is lost. (Reference control schematic in Section

11.1.1)

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Functional Description

3.4.3

Charge State Diagram

Figure 15. Charge State Diagram

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3.4.4

Fresh Air, Recirculated Air State Diagram

Functional Description

Figure 16. Fresh Air / Recirc. State Diagram

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Functional Description

3.4.5

Cooling Discharge State Diagram

Figure 17. Cooling Discharge State Diagram

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