Dometic Battery-Powered Auxiliary Air Conditioning System - Manual (Page 10)

Insulation
Most truck cabs and sleepers are insulated with a value of
approximately R1 to R1.25. Even the cold-weather packages
offered with some new trucks have an insulation value of only
R2. By comparison, most new homes are insulated to R30. TMC
recommended practices call for R4.2 as a standard insulation package
and greater than R4.6 in a premium package. This standard, once
adopted by the industry, will go a long way toward improving the cooling
efficiency of your engine-off air conditioner.
If you are ordering a new truck, we strongly recommend requesting the upgraded insulation package. There
are also measures you can take to reduce the heat load in your truck. Insulate the floors with foam under
the carpet. Get heavy-duty blackout curtains between the cab and sleeper. Cover the skylights and windows
with reflective shades when stopped. Park in the shade whenever possible, and switch off heat-producing
appliances.
Replacing batteries
Major-brand replacement AGM batteries are available from distributors throughout North America. Do not mix
battery types. Example: One would not have 4 typical wet-cell, lead-acid batteries and 4 agm batteries. Overall
charging will not occur and battery life will be reduced.
Maintenance
Voltage Drop: The voltage drop is measured between the charging point (alternator or battery charger) and the
battery that is the farthest from the charging point and should be no more than 0.2V DC. (Any more will result
in improper charging and run time will be shortened.)
Inspect the batteries frequently. Check for tight electrical connections and also check for corrosion at battery
terminals.
Inspect and clean the air filter regularly to ensure good airflow across the evaporator coil. You will find the air
filter in the return-air path, either directly behind the grill or in front of the evaporator coil on the unit.
Do not block the airflow path between the return-air grill and evaporator coil with pillows, blankets, papers or
other objects.
Check the condensate drain to make sure water is draining properly. If the drain is clogged, clean it.
Periodically inspect for chafe on outside wires, cables and refrigerant lines.
Inspect and clean debris from the condenser unit mounted outside the truck.
Note that you should never need to recharge the refrigerant loop under normal operating conditions. If the
refrigerant level needs to be adjusted, federal law requires that it must be done by an EPA-licensed HVAC
technician with proper tools to avoid accidental discharge of refrigerant gas into the air.
OPERATION AND
MAINTENANCE
10