29
oil and cause eventual motor failure. Conduct annual dry oper-
ation 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. Clean coil with
a stiff brush, vacuum cleaner, or compressed 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 solu-
tion. The acid can stain hands and clothing, damage concrete,
and, without inhibitor, damage steel. Cover surroundings 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. 22.
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. 23.
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-410A refrigerant, find equivalent saturated con-
densing 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. If the measured liquid line temperature does
not agree with the required liquid line temperature, ADD
refrigerant to raise the temperature or REMOVE refriger-
ant (using standard practices) to lower the temperature
(allow a tolerance of ± 3° F).
CAUTION
Follow all safety codes. Wear safety glasses and rubber
gloves when using inhibited hydrochloric acid solution.
Observe and follow acid manufacturer’s instructions.
Fig. 22 — Gravity Flow Method
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
SUCTION
PUMP
SUPPORT
TANK
FINE MESH
SCREEN
RETURN
GAS VENT
PUMP
PRIMING
CONN.
GLOBE
VALVES
SUPPLY
1” PIPE
CONDENSER
REMOVE WATER
REGULATING VALVE
Fig. 23 — Forced Circulation Method