Bryant R-22 Thermistor Curve, Header-PinHousing, EnergizingWindings, Vi. Troubleshooting

		1			C - TRANSFORMER COMMON
		2			R - TRANSFORMER LINE
		3
		4
		5			W2 - FIRST STAGE AUXILIARY HEAT
		6			O - REVERSING VALVE
		7			Y2 - SECOND STAGE COOLING/HEAT PUMP
		8			Y1 - FIRST STAGE COOLING/HEAT PUMP
		9			W3 - SECOND STAGE AUXILIARY HEAT
		10			L - MALFUNCTION LIGHT
		11			4 - TON		IF NO JUMPER IS
		12
							INSTALLED, DEFAULT
		13
					5 - TON		IS 3 - TON
		14
		15
		16
		17			JUMPER FOR
		18			HEAT PUMP ONLY			A93576
			Fig. 37—Header-Pin Housing
T3	T8			T7		T2		T1

EXTERNAL MAIN

MAIN WINDING

4 POLE START

	2 POLE START
HIGH SPEED	LOW SPEED
(L1) T1 + T7	(L1) T1
(L2) T2 + T3	(L2) T7 + T8

A92015

Fig. 38—Energizing Windings

TABLE 18—TWO-SPEED COMPRESSOR (WINDING RESISTANCE AT 70°F ± 2 °)

WINDING	3 TON	4 TON	5 TON
T1-T2	0.80	0.70	0.60
T1-T3	3.20	2.20	1.80
T1-T7	1.30	1.00	1.00
T1-T8	3.10	2.20	2.00

—34—

pressures exceeds 500 psi. The compressor is also protected by 3 PTC devices attached to the motor windings. The PTC’s resistance is sensed by the 2-speed control board. See Table 16 for resistance ranges.

MECHANICALLY INTERLOCKED CONTACTORS

The 2-speed products are equipped with mechanically interlocked contactors. Each contactor has interconnecting linkage, providing independent interlocks.

The 2-speed control provides the electrical interlock. The contac- tors are supplied with 240v coils, which reduce the va require- ments of the low-voltage (24vac) control system.

TEMPERATURE THERMISTORS

Thermistors are electronic devices which sense temperature. As the temperature increases, the resistance decreases. Two ther- mistors are used to sense temperature: one senses outdoor ambient, and the other senses coil temperature (heat pump only). Refer to Fig. 39 for resistance values versus temperature.

If the outdoor ambient thermistor should fail, a malfunction signal appears on the indoor thermostat and 2-speed control. The control does not initiate second-stage latching, crankcase heater is turned on during all off-cycles, heating defaults to high speed, and defrost initiates on demand from coil thermistor. (See Table 17.)

THERMISTOR CURVE

	90
(KOHMS)	80
	70
	60
RESISTANCE	50
	20
	40
	30

10

0

0 20 40 60 80 100 120

TEMPERATURE (DEG. F)

A91431

Fig. 39—Resistance Values Versus Temperature

If the outdoor coil thermistor should fail, a malfunction signal appears on the indoor thermostat and 2-speed control. The control defrosts every 90 minutes of heating operation and terminates in 5 minutes. (See Table 17.)

V. LED FUNCTION/MALFUNCTION LIGHTS

The 2-speed control is equipped with an LED function/ malfunc- tion light.

NOTE: Only malfunction signal appears at thermostat. Both function and malfunction signals appear at control board. (See Fig. 33 for LED location.) Table 15 provides the function/malfunction code, location, and definition.

VI. TROUBLESHOOTING

NOTE: Troubleshooting charts for air conditioning and heat pump units are provided in the back of this manual — see Fig. 52, 53, and 54.

COMPRESSOR WINDING CHECK

The 2-speed compressor is nothing more than 2 single-phase motors within 1 compressor shell. When the compressor fails to start or run, there are 3 tests that can be made: open, ground, or short. This compressor has no internal line-break overload; how- ever, it does have PTC motor protectors. See Compressor PTC- Overload Protection section for PTC overload information.