Bryant 548F User Manual download pdf (Page 39)

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the first stage of cooling is satisfied, there is a 30-second delay

before the evaporator fan shuts off. The damper then moves to

the fully closed position. When using a continuous fan, the

damper moves to the minimum position.

E. Heating, Units With Economizer

Upon a call for heat through W1, the IFC energizes to start

the evaporator fan and the economizer damper blade opens

to the minimum position. If the accessory two-position

damper is used, the outdoor-air damper opens to the mini-

mum position whenever the evaporator fan runs. If unit is

equipped with 2 stages of heat, when additional heat is

needed a call is made through W2.

As space temperature approaches the heating temperature

set point, heating stages cycle off. Economizer or two-posi-

tion damper returns to fully closed position.

F. D e f rost

As frost builds up on the outdoor coil, the coil temperature

drops below 28 F. When this outdoor-coil temperature drop is

sensed by the defrost thermostat (DFT) and the defrost timer

is at the end of a timed period (adjustable at 30, 50, or 90

minutes), the unit operates in a defrost cycle controlled by the

defrost timer and thermostat. During this cycle, the reversing

valve solenoid (RVS) is energized and the outdoor fan shuts

off. The electric heaters (if installed) will be energized.

The unit continues to defrost until the coil temperature as

measured by DFT reaches 65 F, or the duration of defrost

cycle completes a 10-minute period.

At the end of the defrost cycle, the electric heaters (if

installed) and the reversing valve will be deenergized, and

the outdoor-fan motor will be energized. The unit will now

operate in the Heating mode.

If the thermostat is satisfied during a defrost cycle, the unit

will continue in the Defrost mode until the time or tempera-

ture constraints are satisfied.

SERVICE

I. CLEANING

Inspect unit interior at the beginning of each heating and

cooling season and as operating conditions require.

A. Indoor Coil

1. Turn unit power off and tag disconnect. Remove filter

access panel and indoor coil access panel.

2. If accessory economizer is installed, remove econo-

mizer by disconnecting Molex plug and removing

economizer mounting screws.

3. Slide filters out of unit.

4. Clean coil using a commercial coil cleaner or dish-

washer detergent in a pressurized spray canister.

Wash both sides of coil and flush with clean water.

For best results, back-flush toward return-air section

to remove foreign material. Flush condensate pan

after completion.

5. Reinstall economizer and filters.

6. Reconnect wiring.

7. Replace access panels.

B. Outdoor Coil

Inspect coil monthly. Clean outdoor coil annually, and as

required by location or outdoor-air conditions.

One-Row Coils

— Wash coil with commercial coil cleaner. It

is not necessary to remove top panel.

2-Row Coils — Clean coil as follows:

1. Turn off unit power and tag disconnect.

2. Remove top panel screws on outdoor end of unit.

3. Remove outdoor coil corner post. See Fig. 35. To hold

top panel open, place coil corner post between top

panel and center post. See Fig. 36.

4. Remove device holding coil sections together at

return end of outdoor coil. Carefully separate the

outer coil section 3 to 4 in. from the inner coil section.

See Fig. 37.

5. Use a water hose or other suitable equipment to flush

down between the 2 coil sections to remove dirt and

debris. Clean the outer surfaces with a stiff brush in

the normal manner.

6. Secure the sections together. Reposition the outer coil

section, and remove the coil corner post from between

the top panel and center post. Install the coil corner

and center posts, and replace all screws.

C. Condensate Drain

Check and clean each year at start of cooling season. In win-

ter, keep drain dry or protect against freeze-up.

D. Filters

Clean or replace at start of each heating and cooling season,

or more often if operating conditions require it. Replacement

filters must be same dimensions as original filters.

E. Outdoor-Air Inlet Screens

Clean screens with steam or hot water and a mild detergent.

Do not use disposable filters in place of screens.

II. LUBRICATION

A. Compressor

The compressor is charged with the correct amount of oil at

the factory.

B. Fan Motor Bearings

Fan motor bearings are permanently lubricated. No further

lubrication of outdoor- or indoor-fan motors is required.

III. OUTDOOR-FAN ADJUSTMENT (FIG. 38)

1. Shut off unit power supply and tag disconnect.

2. Remove outdoor-fan assembly (grille, motor, motor

cover, and fan) by removing screws and flipping

assembly onto unit top cover.

3. Loosen fan hub setscrews.

4. Adjust fan height as shown in Fig. 38.

5. Tighten setscrews.

6. Replace outdoor-fan assembly.

IV. BLOWER BELT ADJUSTMENT

Inspect blower belt for wear, proper belt tension, and pulley

alignment as conditions require or at the beginning of each

heating and air conditioning season. Refer to Step 7 —

Adjust Evaporator Fan Speed on page 20 for adjustment and

alignment procedure.

V. ECONOMIZER ADJUSTMENT

Refer to Optional Economizer sections on pages 13 and 16.

VI. HIGH-PRESSURE SWITCH

Located on the compressor hot gas line is a high-pressure

switch containing a Schrader core depressor. This switch

opens at 428 psig and closes at 320 psig. No adjustment is

necessary. Refer to Table 1.

CAUTION:

1 2 ... 34 35 36 37 38 39 40 41 42 43 44 ... 47 48

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Bryant 548F User Manual Page 39

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