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Compressor — Conduct annual amperage checks to in-
sure that amp draw is no more than 10% greater than indicated
on the serial plate data.
Fan Motors — All units have lubricated fan motors. Fan
motors should never be lubricated unless obvious, dry opera-
tion is suspected. Periodic maintenance oiling is NOT recom-
mended as it will result in dirt accumulating in the excess oil
and cause eventual motor failure. Conduct annual dry opera-
tion check and amperage check to ensure amp draw is no more
than 10% greater than indicated on serial plate data.
Condensate Drain Cleaning — Clean the drain line
and unit drain pan at the start of each cooling season. Check
flow by pouring water into drain. Be sure trap is filled to main-
tain an air seal.
Air Coil Cleaning — Remove dirt and debris from evap-
orator coil as required by condition of the coil. A 10% solution
of dishwasher detergent and water is recommended for
cleaning both sides of the coil, followed by a thorough water
rinse. Clean coil with a stiff brush, vacuum cleaner, or com-
pressed air. Use a fin comb of the correct tooth spacing when
straightening mashed or bent coil fins.
Condenser Cleaning — Water-cooled condensers may
require cleaning of scale (water deposits) due to improperly
maintained closed-loop water systems. Sludge build-up may
need to be cleaned in an open water tower system due to
induced contaminants.
Local water conditions may cause excessive fouling or
pitting of tubes. Condenser tubes should therefore be cleaned at
least once a year, or more often if the water is contaminated.
Proper water treatment can minimize tube fouling and
pitting. If such conditions are anticipated, water treatment
analysis is recommended. Refer to the Carrier System Design
Manual, Part 5, for general water conditioning information.
Clean condensers with an inhibited hydrochloric acid
solution. The acid can stain hands and clothing, damage
concrete, and, without inhibitor, damage steel. Cover sur-
roundings to guard against splashing. Vapors from vent pipe
are not harmful, but take care to prevent liquid from being
carried over by the gases.
Warm solution acts faster, but cold solution is just as effec-
tive if applied for a longer period.
GRAVITY FLOW METHOD — Do not add solution faster
than vent can exhaust the generated gases.
When condenser is full, allow solution to remain overnight,
then drain condenser and flush with clean water. Follow acid
manufacturer’s instructions. See Fig. 29.
FORCED CIRCULATION METHOD — Fully open vent
pipe when filling condenser. The vent may be closed when
condenser is full and pump is operating. See Fig. 30.
Regulate flow to condenser with a supply line valve. If
pump is a nonoverloading type, the valve may be fully closed
while pump is running.
For average scale deposit, allow solution to remain in con-
denser overnight. For heavy scale deposit, allow 24 hours.
Drain condenser and flush with clean water. Follow acid manu-
facturer’s instructions.
Checking System Charge — Units are shipped with
full operating charge. If recharging is necessary:
1. Insert thermometer bulb in insulating rubber sleeve on
liquid line near filter drier. Use a digital thermometer for
all temperature measurements. DO NOT use a mercury
or dial-type thermometer.
2. Connect pressure gage to discharge line near compressor.
3. After unit conditions have stabilized, read head pressure
on discharge line gage.
NOTE: Operate unit a minimum of 15 minutes before
checking charge.
4. From standard field-supplied Pressure-Temperature
chart for R-22, find equivalent saturated condensing
temperature.
5. Read liquid line temperature on thermometer; then
subtract from saturated condensing temperature. The dif-
ference equals subcooling temperature.
6. Compare the subcooling temperature with the normal
temperature listed in Table 21. If the measured liquid line
temperature does not agree with the required liquid line
temperature, ADD refrigerant to raise the temperature or
REMOVE refrigerant (using standard practices) to lower
the temperature (allow a tolerance of ± 3° F).
Follow all safety codes. Wear safety glasses and rubber
gloves when using inhibited hydrochloric acid solution.
Observe and follow acid manufacturer’s instructions.
FILL CONDENSER WITH
CLEANING SOLUTION. DO
NOT ADD SOLUTION
MORE RAPIDLY THAN
VENT CAN EXHAUST
GASES CAUSED BY
CHEMICAL ACTION.
PAIL
FUNNEL
CONDENSER
PAIL
3’ TO 4’
VENT
PIPE
5’ APPROX
1”
PIPE
Fig. 29 — Gravity Flow Method
SUCTION
PUMP
SUPPORT
TANK
FINE MESH
SCREEN
RETURN
GAS VENT
PUMP
PRIMING
CONN.
GLOBE
VALVES
SUPPLY
1” PIPE
CONDENSER
REMOVE WATER
REGULATING VALVE
Fig. 30 — Forced Circulation Method