NFT: Car Problems: Issue with A/C is Driving Me Nuts!!

BBI Gearheads

I have a 2013 Chevy Avalanche that has had an issue with the A/C for over a year now. I have taken the vehicle to the dealer on 3 separate occasions and recently to a local mechanic twice. No one can seem to get the issue resolved.

When the A/C is on, I will hear a cross between feedback & whistling typically when stressing the engine (accelerating while driving). This only happens when the A/C is on. I do not hear this when the heat is on or if the climate control is completely off. Both times dealer/private mechanic performed a dye test, both times leaks were found. So several new lines, o-rings, pulley replacement, coolant recharges, and most recently a new condenser later I am still hearing the noise. The only thing they haven't changed is the compressor which seems to be operating as intended.

I will say each time I take it in, the noise becomes less noticeable...but then it gets worse to the point I cannot take it anymore and take it back in. This makes me think coolant is still leaking and the noise intensifies as the coolant pressure/levels decrease.

The vehicle is off warranty. I don't what this to continue to be a treasure expedition for my mechanic or the dealer. Anyone ever encounter such an issue? Could it be a leak somewhere where it would be difficult to pick up the dye? Perhaps somewhere near the vents behind in the dash? What else could it possibly be other than a leak since I never hear it unless the A/C is on? Any tips/experiences or guidance would be appreciated. I just paid the damn thing off and it hasn't even broke 50K and I do not want to trade it in!!! :-)