IM 368 / Page 13 of 20 (Rev. 11/03)
Recommended Spare Parts
An inherent advantage of the incremental system is that failure
of any part affects only one incremental conditioner and does not
interrupt the operation of the rest of the system. A further
advantage is that a failed part can be quickly and easily replaced,
thus minimizing the inoperative time of the equipment. This is so,
however, only if a replacement part is quickly available. In order
to replace a failed part quickly and keep all incremental
conditioners in good operating condition, McQuay International
recommends that at the time incremental conditioners are
purchased, owners arrange for a small stock of replacement parts.
Where an owner carries such a stock, immediate replacement
of a defective part is possible. The defective part can then be
returned to McQuay International or one of its authorized service
stations. So long as it is still in warranty, it is repaired or replaced
and returned to the owner without cost for shop labor and
material. Thus, the stock of replacement parts is constantly
replenished. To the right is listed the kinds of parts which McQuay
International recommends to be carried in stock, together with
the quantity of parts recommended per 100 incremental
conditioners installed.
Part Name
Cooling Chassis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Compressor Overload Device . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Compressor Running Capacitor . . . . . . . . . . . . . . . . . . . . . . . . . .
Conditioned Air Fan Motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Condenser Fan Motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Condenser Fan Motor Capacitor . . . . . . . . . . . . . . . . . . . . . . . . . .
Pushbutton Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Damper Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Thermostat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Knob for Thermostat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control Relay (if used) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Damper Motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electric Resistance Heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Touch-up Paint (1 pt. spray can) . . . . . . . . . . . . . . . . . . . . . . . . . .
For the current spare parts list, and applicable prices, see your
McQuay representative or write McQuay Service, P.O. Box 1551,
Minneapolis, MN 55440.
Qty Per
100 Units
1
1
1
1
1
1
2
2
2
6
1
2
1
1
Refrigeration Cycle
Every motor-driven refrigeration system operates on the Carnot
cycle. A practical understanding of what goes on at the various
steps in this cycle can be a big help to the troubleshooting
mechanic. Figure 18 illustrates the refrigeration cycle. The
diagram shows what occurs in each component of a hermetically
sealed system, as used in all AAF–McQuay Incorporated
equipment. The temperatures shown are typical of what they might
be when the air entering the condenser (outdoor temperature) is
95
°
F (35
°
C) and the temperature of the conditioned space is 75
°
F
(24
°
C) to 80
°
F (27
°
C).
Figure 18. Refrigeration Cycle
