Carrier T-326 - Manual (Page 8)

6 T--326
Pressure Switch -- The systems use high and low pressure
switches wired in series to control the power circuit of the
compressor clutch relay. If either pressure switch opens,
interrupting the circuit to the clutch relay, the operation of the
compressor will stop. When conditions return to normal the switch
will automatically reset and the compressor will resume operating.
The switches are non--adjustable.
Freeze--Up Thermostat -- Freeze--up thermostats are used to
prevent ice formation on the evaporator coil, which is an indication
that liquid refrigerat is getting back to the compressor. Carrier
Transport Air Conditioning systems use a freeze thermostat
(freezestat) wired in series with the system pressure switches and
thermostat/thermistor to control the operation of the compressor
clutch.
Refrigerant -- A refrigerant is a material that is used to move heat
from the passenger compartment to the outside air. It is a
substance that gives up heat by condensing at high temperature
and pressures and absorbs heat by evaporating at low
temperatures and pressures. The heat transfer properties
exhibited when refrigerant changes state is the foundation of the
refrigerant cycle.
1.5 MODEL AND SERIAL NUMBER TAGS
In order to identify the air conditioning components you have, you
will need to know the model number and serial number. All Carrier
Transport Air Conditioning evaporators, condensers and
compressors have a model/serial number tag located on the
assembly. See Figure 1-2 for skirt mounted condenser data tag
location, Figure 1-3 for the CM--7/11 rooftop condensers data tag
location, Figure 1-4 for GEN 4 (Excel) evaporator data tag location
and Figure 1-5 for GEN 5 evaporator data tag location. Knowing
these locations and the information on the data tags will aid you in
identifying the correct service procedures.
Figure 1-2 Skirt Mounted Condensers