Escapees March/April 2016

Photo courtesy of www.gorving.com .

Your RV Refrigerator Part 4—controllers and recalls By Paul Unmack, PE-CSE, ME #116483, www.arprv.com

with a thermometer and then turn the cooling process on and off to control the refrigerator cabinet temperature, but most of us have better things to do with our time; thus, making the automatic controller essential. Types of Controls There are two basic types of controls found on RV refrigerators. The ¿ rst type is the manual control, a mechan- ical-type control in the sense that no electricity is needed for power. The manual control is easy to recognize because the operator must manually initiate the heat source when using LP (liquid propane) gas. The opera- tor holds down a button and uses an igniter to light the LP gas À ame. Once

In the previous installments of this series, I discussed how the cooling unit works. Then I covered how heat is applied in order to drive the cooling process. Like all systems, something has to control the cooling process to make it work in a manner that is useful and safe. Who wants their iceberg lettuce to actually resemble an iceberg? It is the job of the refrigerator controller to insure the temperature within the refrigerator is kept within desirable limits and that the process does not have any errors.

cooling unit is binary. It is either on or off, and it is the average time that the unit is on or off that determines the temperature inside the refrigera- tor cabinet. If the cooling unit is on full-time, everything becomes frozen inside the refrigerator. If it is never on, the temperature inside the refrig- erator gets too hot and food spoils. You could monitor the temperature inside your refrigerator yourselft

Refrigeration Controllers All refrigeration controllers have one commonality: They have a temperature sensor that monitors the temperature inside the refrigera- tor. The temperature sensor itself is monitored by the controller. When the temperature is out of range, the controller turns on the refrigeration process to cool the refrigerated space. You might say that the control of the

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