I have a Goodman CPRT36-T heat pump that is cycling very fast in both heat and cooling modes. The unit makes a noice every 10-15 seconds and the lights dim also. My house lights have always dimmed slightly when the unit kicks on so I'm pretty sure the compressor is attempting to start. Although the noise I hear is not the full compressor starting noise.

I left the unit off last night for over 12 hours and the problem continued the morning, although the heat and A/C work to some degree, I didn't leave it on long enough to get to the temp set on the thermostat.

Thanks

Thanks everyone for the help, but the technician checked it today and said it is the compressor.

Weird thing with Goodman, the manufacturer.... the tech called his office and they called Goodman and they said the unit was out of warranty based on the serial which starts yymm. My serial is 0602, and the paperwork says, when in doubt about the installation date, "the warranty period starts three months AFTER the manufacture date"

They tried to disallow my coil warranty repair last year even though I had documentation and a paid credit card receipt! Not to mention that the replacement coil came to my home DEFECTIVE, and had to call the techs out a week later to repair a defective schrader valve. It took weeks, threats and I had to sign a disclaimer to get the money back for the techs time to repair their defective coil!