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NOTE
The Variable Capacity Compressor looks very similar to a standard single speed compressor.
The three terminals on the outside of the compressor are arranged the same with either style of
system. When taking resistance measurements around the terminals on the outside of the case
do not let the different motor design cause confusion. The first check is to still verify that there
is NO continuity to the case itself. This is the same as with any standard compressor. When
checking between the three terminals, the resistance measurements should be equal regardless
of which two terminals you are checking. There are three identical windings attached to these
terminals so the resistance of the windings should be equal.
Because of the frequency of the following voltage tests, not all Multimeters may be capable of
measuring the correct voltage. These tests were made using a good quality Multimeter. The
same checks made with a more economical meter resulted in severely lower voltage readings.
The voltages read by your meter will most likely not match the readings made with another
meter. The goal is to verify the presence of drive signals. The signal from the Main Control
board to the VCC board should read around 2.3VAC. This measurement has been quite
consistent with several different meters. The drive signal from the VCC control board to the
compressor is the one that will vary based upon the meter.
There are three outputs to the compressor. These are at CN05, pins 1, 3 and 6. The voltage
read between any pair of these three wires should be the same. If you read 230VAC between
pins 1 and 3 you should also read 230VAC between pins 1 and 6 as well as 230VAC between
pins 3 and 6. Likewise, if your meter registers 195VAC between pins 1 and 3 the readings
between pins 1 and 6 and pins 3 and 6 should be 195VAC.
The easiest way to assure that the compressor is being driven at full speed is to activate service
test #16 in the service mode. To drive the compressor at the minimum speed, activate service
test #17 (see Service Test section). The system must be allowed 5 minutes of off time before
activation of service test #16 or test #17. If five minutes have not elapsed, the compressor
PCB will not allow drive output to the compressor until the five minutes have elapsed. Service
Tests #16 and #17 will automatically cancel after three minutes.
If the compressor is not operating the first check should be confirmation of a drive signal from
the Main Control Board to the Compressor PCB. A check of the AC voltage between pins 1 and
2 of JP10 will give a reading of approximately 2.3VAC. If the 2.3VAC drive signal is present, the
Main Control Board is sending the proper drive signal.
The next step is to verify that the line voltage is available to the Compressor PCB at CN01
between pins 2 and 5. If the AC voltage is available, check for output to the compressor.
Referencing CN05, pin 1, an AC voltage check to pin 6 will read approximately 230VAC with
the compressor running at full speed. While running at the lowest speed, the measured output
voltage may only be 130VAC. If the output voltage is present when checking between pins 1
and 6 on CN05, move the probes to check between pins 1 and 3 of CN05 and finally between
pins 3 and 6 on CN05. The readings in all of the three checks should be the same, if the
voltage checks are equal and the compressor is not operating, suspect a failed compressor.
There is no way to operate this compressor with a compressor start kit. The compressor must
be driven by the solid-state control board.
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