Service; Cleaning Double-Wall Interiors; Coil Cleaning; General - Carrier 39T Installation, Start-Up And Service Instructions Manual

COILS
Chilled Water Coil — Typical coil vents, drains, and lifting
points are shown in Fig. 41. Open the vent plug, partially
turn on the water supply until air is exhausted, and replace
the vent plug. Fully turn on the water supply.
Direct Expansion Coil — Charge with refrigerant. Refer to
Condensing Unit instructions. Refrigerant operating charge
is shown in Table 7, page 19.
Steam Coil
1. Generate steam in the steam main and open the supply
(gate) valve to the coil.
2. Thoroughly preheat the coil with steam before starting
fans, especially when inlet air temperature is below freez-
ing. If water hammer occurs, turn off fans until con-
densate trapped in coils is reduced by heat and steam
pressure.
3. Ensure continuous-vent petcock is open; also check op-
eration of gate valves, control valve, and check valves.
4. After operating coil for 50 hours, check strainer and re-
move any foreign matter. Check traps and drip lines for
correct condensate removal. Where necessary, increase the
pitch of lines to increase condensate drainage. (Recheck
operation after 50 hours and repeat if necessary.)

ELECTRIC HEATERS

1. Check tightness of all electrical connections.
2. Remove heater circuit fuses.
3. Turn on power to activate transformer.
4. Start up base unit fans. Check airflow and switches. Re-
fer to base unit instructions as required.
5. Set thermostats so that heater contactors will operate.
6. Shut off unit power.
7. Reinstall fuses.
8. Turn on unit power and heater power.

SERVICE

Electric shock hazard. Disconnect power before enter-
ing or servicing unit.
More than one disconnect switch may be required to deen-
ergize the equipment.

General

1. Place a suitable walkway to protect floor insulation when-
ever entering the fan section.
2. Review Safety Considerations at beginning of these in-
structions. Good safety habits are important tools when
performing service procedures.
3. To make speed measurements, use a strobe-style tachom-
eter or calculate per Step 7 of Start-Up, Checklist.
Electric Heaters —
erating season or whenever unit is serviced, check field and
factory-made electrical connections for tightness. Also pe-
riodically clean filters, fan, airways, ductwork, grilles, and
registers as required. Differential air pressure switch is fac-
tory set to open at 0.07 in. wg, close at 0.05 in. wg and re-
quires no adjustment.
See Table 24, Electric Heater Troubleshooting Chart. Heater
electrical data is shown in Table 22.

Fan Motor Replacement

1. Shut off motor power.
2. Disconnect and tag power wires at motor terminals.
3. Loosen motor brace-to-mounting-rail attaching bolts. Loosen
belt tensioning bolts to adjust the motor position so V-belts
can be removed without stretching over grooves.
4. Mark belt as to position. Remove and set aside belts.
5. Remove motor to motor bracket holddown bolts.
6. Remove motor pulley and set aside.
7. Remove motor.
NOTE: It may be necessary to remove the end panel to
remove larger motors for some unit sizes.
8. Install new motor. Reassemble by reversing Steps 3-7.
Be sure to reinstall multiple belts in their original posi-
tions. Use a complete new set if required. Do not stretch
belts over sheaves. Review the sections on motor and sheave
installation, sheave alignment, and belt tensioning on
pages 38 and 39.
9. Reconnect motor leads, remove tags, and restore power.
Check fan for proper rotation as described in Start-Up,
Checklist.
Cleaning Double-Wall Unit Interiors —
with solid inner walls, wipe walls with cleaning solution. To
avoid damaging the insulation, do not spray or hose out the
interior.
Coil Cleaning —
dirty over a period of time, especially if air filter mainte-
nance is neglected. Dirty coils can contribute to loss of cool-
ing or heating capacity and efficiency, increased operating
costs, and compressor problems on direct expansion sys-
tems. Dirt, grease, and other oils can also reduce the wet-
tability of the coil surfaces which can result in moisture blow-
off from cooling coils and resulting water leakage problems.
Coils should be inspected regularly and cleaned when nec-
essary. Dust and light dirt should be removed using a vacuum
with a soft-brush tip before using detergents. Apply a mild
non-foaming commercial coil cleaner or dishwasher deter-
gent such as Electrasol using a garden-type sprayer. Rinse
coil gently with warm water, avoiding high-pressure sprays
which can damage coil fins. Ensure that condensate line
is open. Excess water from cleaning may flood unit if con-
densate line is plugged. Depending upon the unit configu-
ration, it may be necessary to remove the coils to thoroughly
clean them.
74
At least once a year at start of op-
Cooling and heating coils can become
For units