Refrigerator User Manual

6-3

Machine Compartment Components (continued)

Starting Device Operation

The starting device is an assembly consist-

ing of an overload (1) and a PTC relay (2).

The PTC relay is composed of a semi con-

ductive substance formed in the shape of a

disk (2). The disk is connected in series with

the run and start terminals which in turn con-

nect to the run and start windings. The resis-

tance of the disk material is relatively low at

room temperature. When voltage is applied

andcurrentowstothecompressorwind-

ings,thecurrentowingtothestartwinding

heats the disk material. As the temperature

of the disk increases, the resistance of the

diskincreasesrapidlyandlimitscurrentow

to the start winding. At the same time cur-

rentowthroughthediskisdecreasing,

theeffectsofcurrentowthroughtherun

capacitor increases. This change in current

and capacitance seen by the start winding

helps start the compressor and allows the

start winding to remain in the circuit once the

compressor is running.

NOTE: Do not disassemble the PTC device. The PTC device (2) was opened to show the inte-

rior construction and to assist in explaining the theory of operation

Checking the PTC: The easiest way to check the PTC device is to replace it with a known good

one. If a new PTC device is not available, a resistance check can be made.

1. Disconnect power to the refrigerator.

2. Disconnect the starting device from the

compressor.

3. Unplug the run capacitor form the

module.

4. Connect an Ohmmeter across the L and

S terminals.

5. If the PTC is at ambient temperature, 70

– 80 degrees F., the approximate

resistance should be between 3 and 10

 OHMs.Aninnitereadingindicatesthe

PTC device is open.

Semi Conductor Disk