(g) The high temperature cutout HTCO and all high and low pressure, safety, and overload controls for the
of any of these safety controls de-energizes K4. Contacts K4X1, K4-X2, and K4X3 open. Relay K5 remains energized
holding K5-X1 open. Thus all electrical components are kept deenergized until the tripped safety or overload resets, and
control switch S1 has been rotated momentarily to the OFF-RESET position.
(h) With the exception of the compressor motor overloads, all safety controls, etc.. as described in step (g)
are in series with evaporator fan thermal cutout TCO to control relay K4. Internal wiring of the compressor has been designed
to incorporate the thermal cutouts within the compressor.
(4) AUTOMATIC MODE HEATING. Operation in the heating mode with S2 in the second and third stages
(a) When the thermostat low-temperature air setting is satisfied, S2 stage 1 (COOL) switches off.
(b) At a temperature nominally 15F below stage 1 turnoff, stage 2 (HEAT 1) switches on.
(c) K7 is energized, supplying 3-phase ac to HR4, HR5, and HR6.
(d) S2 stage 2 cycles with a temperature differential of 3 between on and off.
(e) At a temperature nominally 2-1/2 F lower the stage 2 turn on, stage 3 (HEAT 2) switches on.
(f) K8 is energized, supplying 3-phase ac to HR1, HR2, and HR3.
(g) S2 stage 3 cycles with a temperature differential of 3 between on and off.
With 21/2 F separating stage 2 switch on and stage 3 switch on, each
(5) TEMPERATURE OVERLAP.
having a 3 differential, the low end of stage 2 overlaps the high end of stage 3 by 1/2, avoiding a "dead space" in the
controlled temperature range.
j. AIR CONDITIONER SAFETY CONTROLS.
Table 11 lists
conditioner safety controls,
location in the air conditioner and references applicable maintenance procedures. As illustrated in figure 1-5, all safety
controls are series connected in the circuit of control relay K4. Actuation of any safety control opens the circuit and
de-energizes the air conditioner.