Compressor Solenoid - Bard Q-TEC Series Literature Assembly

COMPRESSOR SOLENOID

A nominal 24-volt direct current coil activates the
internal compressor solenoid. The input control
circuit voltage must be 18 to 28 volt ac. The coil
power requirement is 20 VA. The external electrical
connection is made with a molded plug assembly.
This plug contains a full wave rectifier to supply direct
current to the unloader coil.
Compressor Solenoid Test Procedure – If it is suspected
that the unloader is not working, the following methods
may be used to verify operation.
1. Operate the system and measure compressor
amperage. Cycle the compressor solenoid on
and off at 10-second intervals. The compressor
amperage should go up or down at least 25%.
2. If Step 1 does not give the expected results, shut
unit off. Apply 18 to 28 volt ac to the solenoid
molded plug leads and listen for a click as the
solenoid pulls in. Remove power and listen for
another click as the solenoid returns to its original
position.
3. If clicks can't be heard, shut off power, remove the
control circuit molded plug from the compressor and
measure the solenoid coil resistance (see Table 17).
TABLE 17
Solenoid Coil Resistance
Compressor Model
ZPS***K4
ZPS***K5
ZPS***K6
4. Next, check the molded plug.
Voltage Check: Apply control voltage to the plug wires
(18 to 28 volt ac). The measured dc voltage at the
female connectors in the plug should be around 15 to
27 vdc.
Resistance Check: Measure the resistance from the end
of one molded plug lead to either of the two female
connectors in the plug. One of the connectors should
read close to 0 ohms, while the other should read
infinity. Repeat with other wire. The same female
connector as before should read zero, while the other
connector again reads infinity. Reverse polarity on the
ohmmeter leads and repeat. The female connector that
read infinity previously should now read close to 0 ohms.
Replace plug if either of these test methods does not
show the desired results.
Manual 2100-738A
Page 66 of 71
Solenoid Ohms
33.6 Ω
350 Ω or 1640 Ω
1640 Ω