Bryant LEGACY 213R Service Manual download pdf (Page 13)

Crankcase Heater

Crankcase heater is a device for keeping compressor oil warm. By

keeping oil warm, refrigerant does not migrate to and condense in

compressor shell when the compressor is off. This prevents flooded

starts which can damage compressor.

On units that have a single--pole contactor, the crankcase heater is

wired in parallel with contactor contacts and in series with

compressor. (See Fig. 7.) When contacts open, a circuit is

completed from line side of contactor, through crankcase heater,

through run windings of compressor, and to other side of line.

When contacts are closed, there is no circuit through crankcase

heater because both leads are connected to same side of line. This

allows heater to operate when system is not calling for cooling.

The heater does not operate when system is calling for cooling.

TEMP SWITCH

BLK

2111

BLKBLKBLK

CRANKCASE HTR

A97586

Fig. 7 – Wiring for Single--Pole Contactor

The crankcase heater is powered by high-- voltage power of unit.

Use extreme caution troubleshooting this device with power on.

The easiest method of troubleshooting is to apply voltmeter across

crankcase heater leads to see if heater has power. Do not touch

heater. Carefully feel area around crankcase heater. If warm,

crankcase heater is probably functioning. Do not rely on this

method as absolute evidence heater is functioning. If compressor

has been running, the area will still be warm.

With power off and heater leads disconnected, check across leads

with ohmmeter. Do not look for a specific resistance reading.

Check for resistance or an open circuit. Change heater if an open

circuit is detected.

Time--Delay Relay

The TDR is a solid--state control, recycle delay timer which keeps

indoor blower operating for 90 sec after thermostat is satisfied.

This delay enables blower to remove residual cooling in coil after

compression shutdown, thereby improving efficiency of system.

The sequence of operation is that on closure of wall thermostat and

at end of a fixed on delay of 1 sec, fan relay is energized. When

thermostat is satisfied, an of f delay is initiated. When fixed delay of

90 ± 20 sec is completed, fan relay is de--energized and fan motor

stops. If wall thermostat closes during this delay, TDR is reset and

fan relay remains energized. TDR is a 24v device that operates

within a range of 15v to 30v and draws about 0.5 amps. If the

blower runs continuously instead of cycling off when the fan

switch is set to AUTO, the TDR is probably defective and must be

replaced.

Pressure Switches

Pressure switches are protective devices wired into control circuit

(low voltage). They shut off compressor if abnormally high or low

pressures are present in the refrigeration circuit. Puron pressure

switches are specifically designed to operate with Puronr systems.

R--22 pressure switches must not be used as replacements for the

Puronr air conditioner or heat pump. Puronr pressure switches are

identified by a pink stripe down each wire.

Low--Pressure Switch (A/C

Only)

The low--pressure switch is located on suction line and protects

against low suction pressures caused by such events as loss of

charge, low airflow across indoor coil, dirty filters, etc. It opens on

a pressure drop at about 50 psig for Puron and about 27 for R22. If

system pressure is above this, switch should be closed. To check

switch:

1. Turn off all power to unit.

2. Disconnect leads on switch.

3. Apply ohmmeter leads across switch. You should have

continuity on a good switch.

NOTE: Because these switches are attached to refrigeration system

under pressure, it is not advisable to remove this device for

troubleshooting unless you are reasonably certain that a problem

exists. If switch must be removed, remove and recover all system

charge so that pressure gauges read 0 psi. Never open system

without breaking vacuum with dry nitrogen.

PERSONAL INJURY HAZARD

Failure to follow this caution may result in personal injury .

Wear safety glasses, protective clothing, and gloves when

handling refrigerant.

CAUTION

To replace switch:

1. Apply heat with torch to solder joint and remove switch.

PERSONAL INJURY HAZARD

Failure to follow this caution may result in personal injury .

Wear safety glasses when using torch. Have quenching

cloth available. Oil vapor in line may ignite when switch is

removed.

CAUTION

2. Braze in 1/4--in. flare fitting and screw on replacement

pressure switch.

1 2 ... 8 9 10 11 12 13 14 15 16 17 18 ... 65 66

Comments to this Manuals

No comments

Bryant LEGACY 213R Service Manual Page 13

Comments to this Manuals

Related products and manuals for Heat pumps Bryant LEGACY 213R