Friedrich SH20L50-A SYSTEM CONTROL SWITCH Figure, Capacitor, Run, Capacitor – Test, Thermostat

SYSTEM CONTROL SWITCH (Figure 6)

This switch is double pole, single throw. Check for continuity between terminals 2 and 3, and 5 and 6.

FIGURE 6 SWITCH, ON-OFF

CAPACITOR, RUN

A run capacitor is wired across the auxiliary and main winding of a single phase permanent split capacitor motor such as the compressor and fan motors. A single capacitor can be used for each motor or a dual rated capacitor can be used for both.

The capacitor’s primary function is to reduce the line current while greatly improving the torque characteristics of a motor. The capacitor also reduces the line current to the motor by improving the power factor of the load. The line side of the capacitor is marked with a red dot and is wired to the line side of the circuit (see Figure 7.)

FIGURE 7 RUN CAPACITOR HOOK–UP

COMPRESSOR

FAN

MOTOR

RED DOT

RUN CAPACITOR

CAPACITOR – TEST

1.Remove the capacitor from the unit.

2.Check for visual damage such as bulges, cracks, or leaks.

3.For dual rated capacitors, apply an ohmmeter lead to the common (C) terminal and the other probe to the compressor (HERM) terminal. A satisfactory capacitor will cause a deflection on the pointer, then gradually move back to infinity.

4.Reverse the leads of the probe and momentarily touch the capacitor terminals. The deflection of the pointer should be two times that of the first check if the capacitor is good.

5.Repeat steps 3 and 4 to check the fan motor capacitor.

NOTE: A shorted capacitor will indicate a low resistance and the pointer will move more to the “0” end of the scale and remain there as long as the probes are connected. An open capacitor will show no movement of the pointer when placed across the terminals of the capacitor.

THERMOSTAT

A cross ambient thermostat is used to maintain the desired comfort level. The thermostat reacts only to a change in temperature at the bulb location.

Important to the successful operation of the unit is the position of the sensing bulb in relation to the evaporator (see Figure 8).

FIGURE 8 SENSING

BULB LOCATION

RANGE:

Thermostat

(Part No. 618-225-02)

60° F ( ± 2° ) to 90° F( ± 4° )

6