5-4
5-4
PROBLEM
PROBABLE CAUSE
CORRECTION
9. Evaporator frosting
up.
9a. Low outside air temperature (below
65
°
F).
9a. Instruct customer that opera-
tion at ambient temperatures
below 65
°
F is not considered a
normal requirement of the unit.
Adjust the controls to a warmer
setting.
9b. Check thermistor by placing it
in ice water and check resis-
tance (see chart on page 4-1).
9c. Clean or replace air filter.
Check for obstructed or re-
stricted air passage, dirty
evaporator and blower wheel
loose, or missing seals.
9d. Check for binding of fan blade,
blower wheel, or motor bear-
ings. Use low fan speed and
instruct the customer.
9b. Thermistor failed.
9c. Improper airflow.
9d. Fan motor slow.
10. Remote control does
not operate unit.
10a. Batteries dead.
10a. Check that unit operates
manually at control panel. If it
does, replace batteries in
remote.
10b. Replace remote control.
10b. Remote failed.
11. Moisture dripping into
room.
11a. Extreme humidity.
11a. Advise customer of possible
sweating formations under
abnormal conditions. Check
and improve all possible
seals.
11b. Check and improve all sealed
areas.
11c. Check for proper side-to-side
level of unit. Check for 1/2
″
rear slope (or 1 full bubble)
on spirit level.
11d. Replace styrofoam shield.
11b. Inadequate seal.
11c. Improper level.
12. Excess condensation
running outside.
12a. Extreme humidity.
12a. This condition is normal in
areas of extreme humidity.
NOTE:
90% frosting of
evaporator is normal un-
der low ambient, high
humidity conditions, and
70% ice blockage is to be
considered normal.
NOTE:
Initial startup on
rotary compressor-
equipped units may
cause frosting on the first
2 or 3 evaporator passes
(for approximately 20
minutes) until refrigerant
is driven out of the oil by
heating.
11d. Styrofoam shield under evaporator coil
broken or missing (see photo, on page
3-14).
Diagnostics and Troubleshooting (continued)
FOR SERVICE TECHNICIANS ONLY
