Home A/C Compressor running while system is off.?

Woke up this morning and heard my 45 year old GE Weather Tron A/C - heat pump Compressor running, but my A/C temperature control panel wasn't set for the A/C to run yet. There was frost on the big copper pipe coming from the compressor. The blower, under the house was covered in condensation. I turned off the compressor at the fuse box. Are there any Professionals out there that can tell me what the problem is?