Pressure Switches; Muffler, Accumulator, Reversing Valve (Rvs); Thermistors; Control Box - Bryant Base Series Application Manual And Service Manual

Residential Air Conditioners and Heat Pumps Using R-22 and Puron® Refrigerant: Application Guideline and Service Manual

Pressure Switches

The Puron two-stage air conditioner contains two pressure switches to
prevent system operation if the pressures get excessively high or low.
The air conditioner low pressure switch in the suction line opens at 50
PSI and closes at 95 PSI. The high pressure switch opens at 670 PSI and
closes at 470 PSI. Both pressure switch settings are considerably higher
than on comparably sized R-22 units. The high and low pressure
switches can be identified by their pink stripe on the switch's electrical
wires.
The Puron two-stage heat pump contains a loss of charge switch in the
suction line on 286B and 289B, and liquid line on 226A, 226C, and
CH17 which opens at 23 PSI and closes at 55 PSI. See troubleshooting
section for sequence when a pressure switch trip occurs.

Muffler, Accumulator, Reversing Valve (RVS)

The Puron two-stage air conditioners and heat pumps have a compressor
discharge line muffler, to dampen sound pressure pulsations.
The Puron two-stage heat pumps have a specifically designed reversing
valve, for Puron application and an accumulator for storing excess liquid
refrigerant during the heating mode to prevent damaging flood-back.

Thermistors

Outdoor Ambient Thermistor
The Puron two-speed air conditioner and heat pump units have an
outdoor ambient air thermistor (see
know the outdoor air temperature so it can activate various functions.
These functions include:
• Activating the compressor crankcase heater when ever the outdoor
unit is in the off cycle.
• The fan motor speed changes for both air conditioner and heat
pump on the ECM equipped units.
Outdoor Coil Thermistor (OCT)
The coil or defrost thermistor (see
monitor outdoor air temperature but used in a different configuration.
The control board must know the coil temperature so it can activate
various functions. These functions include:
• Frost sensing on heat pumps
• Coil-vs-Ambient temperature relationship
• Low ambient cooling operation
Thermistor Curve
The resistance vs. temperature chart enables the service technicians to
check thermistor resistance, regardless of the temperature.
For example, at a 60_F / 15.6_C temperature, thermistor resistance
should be around 16,000 Ohms. (See
We will talk about the thermistor in more detail when we review the
control board fault codes.
Fig. 42 – Resistance Values Versus Temperature
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
Fig. 45. The control board must
Fig. 46) is the same thermistor used to
Fig. 42.)

Control Box

Contactor And Capacitor
Removal of the control box cover exposes the control components. Both
air conditioner and heat pump control boxes will appear to be nearly
identical. There are two contactors, two capacitors, a control board and a
compressor start assist. The contactors are identical to those used in the
standard single speed units. One controls low capacity operation and the
second controls high speed. The capacitors also are similar to those used
in standard single speed units. You have a fan capacitor for the outdoor
fan motor, and a run capacitor for the compressor motor. The control
board, start capacitor, and start relay control the starting of the
compressor.
Always replace these devices with the Factory Approved Components.
NOTE: ECM motors are not connected to a capacitor.
Incoming Power
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury or death.
Incoming power is attached to the two power wire stripped leads. A
ground lug is also provided. Outdoor unit should always be grounded
through the ground lug to the unit disconnect and from the disconnect
to the electrical fuse box.
Incoming power is attached to the two power wire stripped leads. A
ground lug is also provided. Outdoor unit should always be grounded
through the ground lug to the unit disconnect and from the disconnect to
the electrical fuse box. Failure to do so can cause serious injury or death.
• First check that the model plug is correct for the unit model and
size, and that it is installed properly
Fig. 43 – Start Relay and Capacitor Mounting Locations
A08054
57
WARNING
!
in Cube Cabinet
A10157