7-4.Temperature Control

Operating principle

 

 

Inspection method

A temperature control is used on all refrigerators and

Put the probe of the ohmmetor to the terminal

freezers to regulate the operation of compressor and

of the temperature control, and check for the

thus maintain desired food temperatures.

opening and closing of the contacts by turning

The temperature control consists primarily of a

the knob ON and OFF.

capillary and billows assembly , a set of normally

 

 

 

closed contacts, and a mechanical linkage.

 

 

 

 

Pressure within the gas- charged capillary

tube and

 

 

 

billows assembly responds to temperature

sensed

 

 

 

at the sensing bulb.

 

 

 

 

 

Rising temperature causes the pressure to

increase

 

 

 

and expand the accordion-type billows.

 

 

 

 

The expanded billows actuates the linkage which

 

 

 

allows contracts to close.

 

 

 

 

 

When the temperature drops ,

the billows contacts

 

 

 

due to a decrease in pressure

and the snap-action

 

 

 

of the linkage opens the contacts.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

10