Carrier 69NT40-541-300, Операция и обслуживание, Страница: 99 / 152

6 − 11 T − 318
d. Remove motor mounting hardware and replace the
motor. It is recommended that new locknuts be used
when replacing motor. Connect wiring per wiring dia-
gram.
e. Install fan loosely on motor shaft (hub side in). DO
NOT USE FORCE. If necessary, tap the hub only, not
the hub nuts or bolts. Install venturi. Apply “Loctite H”
to fan set screws. Adjust fan within venturi so that the
outer edge of the fan projects 3.2 to 6.4mm (3/16”
1/16”) back from edge of the venturi. Spin fan by
hand to check clearance.
f. Close and secure condenser fan screen guard.
g. Apply power to unit and check fan rotation. If fan motor
rotates backward, reverse wire numbers 5 and 8.
6.12 WATER − COOLED CONDENSER CLEANING
The water-cooled condenser is of the shell and coil type
with water circulating through the cupro-nickel coil. The
refrigerant vapor is admitted to the shell side and is
condensed on the outer surface of the coil.
Rust, scale, and slime on the water-cooling surfaces
inside of the coil interfere with the transfer of heat,
reduce system capacity, cause higher head pressures
and increase the load on the system.
By checking the leaving water temperature and the
actual condensing temperature, it can be determined if
the condenser coil is becoming dirty. A larger than
normal difference between leaving condensing water
temperature and actual condensing temperature,
coupled with a small difference in temperature of
entering and leaving condensing water, is an indication
of a dirty condensing coil.
To find the approximate condensing temperature, with
the unit running in the cooling mode, install a gauge 0 to
36.2 kg/cm (0 to 500psig) on the compressor discharge
service valve.
Example: Discharge pressure is 10.3kg/cm
2
(146.4psig). Referring to Table 6 − 8 (R-134a pressure/
temperature chart), the 10.3kg/cm
2
(146.4psig) value
converts to 43 ° C (110 ° F).
If the water-cooled condenser is dirty, it may be cleaned
and de-scaled by the following procedure:
a. Turn unit off and disconnect main power.
b. Disconnect water pressure switch tubing by loosen-
ing the two flare nuts. Install one-quarter inch flare
cap on water-cooled condenser inlet tube (replaces
tubing flare nut). De-scale tubing if necessary.
What You Will Need:
1. Oakite Aluminum Cleaner ® 164, available as a pow-
der in 20kg (44lb) pails and 205kg (450lb) drums.
2. Oakite composition No. 32, available as a liquid in
cases, each containing 3.785 liters (4 U.S. gallon)
bottles and also in carboys of 52.6kg (116lbs) net.
3. Fresh clean water.
4. Acid proof pump and containers or bottles with rub-
ber hose.
NOTE
When Oakite compound No. 32 is being used
for the first time, the local Oakite Technical Ser-
vice representative should be called in for as-
sistance in planning the procedure. They will
advise the reader on how to do the work with a
minimum dismantling of equipment, estimate
the time and amount of compound required,
preparation, how to control and conclude the
de-scaling operation by rinsing and neutralizing
equipment before putting it back into service.
Summary of Procedure:
1 Drain water from condenser tubing circuit.
2. Clean water tubes with Aluminum Cleaner ® 164 to
remove mud and slime.
3 Flush.
4 De-scale water tubes with Oakite No. 32.
5 Flush.
6 Neutralize.
7 Flush.
8 Put unit back in service under normal load and check
head (discharge) pressure.
Detailed Procedure:
1. Drain and flush the water circuit of the condenser
coil. If scale on the tube inner surfaces is accompa-
nied by slime, a thorough cleaning is necessary
before de-scaling process can be accomplished.
2. To remove slime or mud, use Oakite Aluminum
Cleaner ® 164. Mix 170 grams (6 ounces) per 3.785
liters (1 U.S. gallon) of water. Mix cleaner in one half
the volume of water, while stirring, and then add re-
maining water. Warm this solution and circulate
through the tubes until all slime and mud has been
removed.
3. After cleaning, flush tubes thoroughly with fresh
clean water.
4. Prepare a 15% by volume solution for de-scaling by
diluting Oakite compound No. 32 with water. This is
accomplished by slowly adding 0.47 liter (1 U.S. pint)
of the acid (Oakite No. 32) to 2.8 liters (3 U.S. quarts)
of water.