I have a 2002 Chevy1500HD 4x4 that I purchased in 2012 with only 40k miles on it and extremely well taken care of. Its been a great vehicle except one little gremlin that I cannot figure out. The A/C works just fine until I wash it or drive in the rain. While driving in a heavy rain the A/C will just shut down and when any attempt made to restart it the button will just blink 3 times. Sometimes, at random, it will come back on after 20-30 minutes after rain stops or when we get home and let truck sit for 30 min and get back in it to check it will start working fine again. I have read several blogs and tried several suggestions. I tried pressing the A/C button and re-circulation button at the same time to try and reset temp sensor but this did not work. I have replaced the ambient temp sensor and it seemed to help for a little while but the failure is becoming more consistent. Also, I changed the clutch fan, low pressure switch and inspected (as best as I could) all the wires and connectors. It would make sense to me that there could be a short somewhere in the wiring. However, before I start tracking all the wires I am looking for something I may be missing. Any suggestions would greatly be appreciated.

 

Welcome to the forum, the light flashing could indicate that the system thinks its colder out then it is.... water could be influencing that condition... I'd revisit the ambient temp sensor, might have to have it read by a dealership to see what the value the BCM is seeing...
Make sure the connections are clean and sealed...