Newbie needing help with A/C System

[Fuzion]

I have been searching and reading up on the a/c system for a couple of months. I have not come across any threads describing similar issues to what I am having. I would like your opinion on my situation before i take the car to mechanic.

I have a 2003 Celica GT, last summer the A/C stopped working and A/C button was blinking. I came online and searched what could be causing the problem to the system. I found a thread stating that one of the problems could be the a/c relay. It advised to removed the relay for the horn and replace the one for the a/c. I did that and I could instantly see that the a/c compressor was turning on and the ac worked.
Well I went to advanced auto and got a new relay and figured everything was fine.

Well after some time I came to notice that the a/c compressor was turning on pretty much all the time, even if the a/c system was in the off position. I could hear the a/c fan turn on even during cold starts.

Now, I don’t get any cold air from the ac and the blinking light appears when I turn on the defroster, I click it one time and it stays off for the rest of my trip. On cold starts I get a weird squeaking sound that gets louder as the car heats up but then goes away while driving. It is so loud that at first I thought there was some serious engine damage to a bearing or rod. But the car drives fine, oil is fresh at a constant level. The sound comes back faintly when the car comes back to idle. A couple of times now, the engine has cut off on me but started right up with out any problems. This is what has me worried and think that the compressor is close to seizing.

I recently emptied the radiator and replaced it with fresh Toyota coolant and installed a new thermostat. I took the time to make sure there were no air bubbles left in the system and my heat works perfectly.

I do not hear the squeaking increase in speed while the engine is in higher rpm’s. I plan on removing the A/C relay to see if the compressor will stop turning on, but I hope the compressor doesn’t have to be changed bc I understand they cost over $450 bucks.

Could all these issues be caused by a bad relay that I got from advanced auto? Any input would be fabulous. Thanks