Mitsubishi Electric PAA-A18AA1 Service Manual page 17

IMPORTANT
The furnace fan should be configured such that the airflow is greater than or equal to
350 CFM per ton and less than or equal to 400 CFM per ton of nominal PAA unit cooling
capacity.
In downflow orientation, the furnace fan should be configured to maintain an airflow face
velocity below 350 ft/min to prevent water blow-off.
CAUTION
• Do not use the PAA unit in special environments.
– Oil, steam, sulfuric smoke, etc. can significantly reduce the performance of the PAA
unit or damage its parts.
• Always lock the furnace disconnect switch, if present, in the open position prior to
servicing the PAA unit.
• When servicing the unit in a hospital, communication station, or similar place, provide
sufficient protection against electromagnetic noise.
– The INVERTER equipment, private power generator, high-frequency medical
equipment, or radio communication equipment may cause the PAA unit to operate
erroneously, or fail to operate. On the other hand, the PAA unit may affect such
equipment by creating electromagnetic noise that disturbs medical treatment of image
broadcasting.
• Make sure an auxiliary drain pan is installed to prevent occasional condensation from
damaging the building.
• When the room humidity exceeds 80% or when the drain pipe is clogged, condensation
may drip from the indoor unit. Perform collective drainage work together with the outdoor
unit, as required.
• When the ambient dew point temperature exceeds 73° F (23° C), dew condensation
may occur on the unit surface. Perform appropriate treatment, such as duct wrap
insulation, to avoid dew condensation.
NOTE
Keep this service manual with the unit. Carefully read all instructions for the installation
prior to servicing product. Make sure each step or procedure is understood and any
special considerations are taken into account before starting service.
Gather all tools, hardware and supplies needed to complete the service. Refer to these
sections in the PAA unit Installation Manual, "System introduction" and "Indoor unit
accessories", for items that are not included with the PAA unit. Make sure everything
needed to service the product is on hand before starting. If the power source capacity is
inadequate or electric work is performed improperly, electric shock and fire may result.
Specifications are subject to change without notice.
PAA-A18, 24, 30, 36, 42AA1/BA1/CA1 and all-
17 © 2022 Mitsubishi Electric US, Inc.