Hopefully someone could help me. I have a 1/2 hp aquarium chiller and for some reason the compressor will shut off after about 10 minutes of operation. The fan on the condenser coil continues to run. After about a minute the compressor will try to restart, but never successful. I placed a voltmeter on the starting terminal of the compressor(the starting terminal is connected to the starting cap through a relay) and when it initially starts its at about 170V. As it continues to run it slowly decreases and once it fall to about 120V the compressor will shut off. After the compressor shuts off the terminal will measure 0V even when it tries to restart. I have a feeling the compressor is doing this because of low freon or the starting cap could be bad. Although if the compressor will start intially every time then its probably not the starting cap. Any other ideas?? FYI, this chiller is 120VAC and there is no low voltage control and it should always be chilling if its plugged in. Thanks for you help.