WD Catalog 2018

10-4

Chapter 10

– Component Repair or Replacement

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Table of Contents

Index

Troubleshooting for the following components is discussed below:

Binary™ and Trinary™ Switches

Air Operated Controls

CTC™ System

1. Binary™ and Trinary™ Switch—Troubleshooting

The high/low pressure function of the Binary™ and Trinary™ switches

acts as a circuit breaker for the AC system. The switch interrupts current

flow to the clutch when there is abnormal pressure in the system. A

combination of components or wiring problems could cause the system to

malfunction. In many cases, problems associated with these switches are

the result of a malfunction elsewhere in the system.

Note:

Terminal numbers are molded into the top of the

Trinary™ switch. Terminals 1 and 2 control the com-

pressor clutch and are identical to the two terminals

on the Binary™ switch.

AC Compressor Clutch Circuit

In normal operation, the Binary™ and Trinary™ terminals, #1 and

#2, should form a closed circuit. They supply power to the clutch if

the AC system is properly charged with refrigerant, and the outside

air temperature is above 40 degrees Fahrenheit.

AC Clutch Does Not Engage.

With the system on, check power at Trinary™ switch with

voltmeter or trouble light:

a. One of the terminals, #1 or #2, should have power.

b. If there is no power, there is a problem with the AC unit

or wiring.

Both terminals have power:

a. The problem is either the clutch or the wiring from the

switch to the clutch.

Power to and from the Binary™ or Trinary™ check out OK:

a. Use the manifold gauge set to check out system pres-

sures. (Outside temperature must be above 40

F).

b. If system pressure is below 40 PSIG, check for refriger-

ant leaks. If OK, add refrigerant to obtain correct pres-

sure.

AC system pressure and power supply to switch check out

OK:

a. Connect a temporary jumper wire between terminals #1

and #2.

b. The clutch should engage. Operate the AC system for five

minutes at maximum cooling. Disconnect jumper wire

and reconnect the switch leads. If the clutch will not

engage, and pressure is over 50 PSIG, replace the switch.