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ParkSmart Bunk A/C System Freightliner P3 Cascadia

By Larry Turay, MACS Contributor

Since the introduction of the Cascadia platform in 2007, the ParkSmart auxiliary HVAC system has been offered to replace the standard auxiliary HVAC unit. The ParkSmart is a battery-powered A/C system, a fuel operated heater and auxiliary control unit, which eliminates the need for the engine to operate when the operator is in parked mode. This concept helps to reduce emissions and conserves fuel. The system functions differently from the standard auxiliary HVAC system. ParkSmart works in conjunction with the vehicle’s main HVAC system while the engine is running and independent of the vehicle’s main system when the engine is off. It has a 12-volt electric compressor and condenser fan and a fuel operated coolant heater. When the engine is running, the air conditioning unit is powered by the vehicle electrical system, and the auxiliary heater core is supplied using engine coolant. The ParkSmart AGM batteries are connected to the electrical system so they will be recharged by the alternator.

Photo courtesy of Freightliner

The ParkSmart unit contains a stand-alone refrigerant loop separate from the main HVAC system. It is not affected by the front refrigerant system. In the system design from 2007 until July of 2010, the refrigerant, oil and refrigerant charge could not be adjusted, and any problems with components or charge within the refrigerant loop required unit replacement. From 2010-2016, the system was split, and the refrigerant charge could be removed and recharged, oil level adjusted and the refrigerant lines, drier, pressure switch and condenser changed without replacing the components in the bunk area.

The ParkSmart system is designed to maintain an already cooled sleeper area at a comfortable level for a limited amount of time depending on the selected settings and ambient conditions. It is NOT designed to, nor will it cool down a hot sleeper while operating in parked mode! In parked mode, the auxiliary unit operates on a dedicated set of AGM batteries separated from the vehicle’s starting batteries by a bi-stable solenoid interconnect controller. The vehicle’s charging system recharges the batteries when the engine is running.

The ParkSmart unit controls the temperature in the sleeper area with a sensor mounted in the sleeper control panel. The temperature range is from 60 F (15 C) to 85 F (29 C). After the bunk area preconditioned, with the engine running and the bunk curtain open, the unit is designed to maintain a comfortable bunk temperature for up to 12 hours with the bunk curtain closed.

There are three operating modes for ParkSmart: Engine On, Engine OFF, Parked. When the unit is turned on, regardless of the mode or temperature setting, the condenser fan will run for up to 30 seconds.

If the engine is On, the ParkSmart runs on the power supplied by the alternator. While the engine is running, the ParkSmart runs at maximum output, which lengthens the time needed to recharge the batteries after a night with the unit in Parked mode.

If the engine is Off, and the key OFF, pushing the PARK button with the blower in any mode but 0, activates the parked mode; it draws power from all eight batteries until battery voltage reaches 12.5 Volts. Then the bi-stable solenoid separator will open and the ParkSmart will run on the back batteries’ unit voltage reaches 11.3 Volts, and the unit shuts down.

If the engine is OFF and the key is in the ACC or ON position, the unit operates in ventilation mode, running the blower but not the compressor. The PARK button must be pushed to turn on the compressor.

The system consists of parts and technologies provided to Freightliner by three suppliers; Valeo, Bergstrom and Esper. Due to the differences between normal HVAC systems and the ParkSmart, there is confusion in the field about how the system is designed to work and how it should be serviced. These concerns will be covered next issue!

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