Last summer due to poor cooling I had my AC checked and the garage had replaced my receiver/dryer. Dye was added to the system and now leaks are present this year. However, I noticed during the winter when I had on the defroster, the compressor was cycling every 10 - 15 seconds as if low freon was in the system. Now that it is June I turned on the AC and the system works fine but the cycling is present. I noticed that when the truck is in park there is no cycling, but when in drive it cycles. Is this an electrical problem? What should be checked and replaced?