Well ... crap. Yesterday while switching to defrost to get it to kick in, one time I got a loud thump while engaging on the freeway. Check engine light came on (random misfire). Turned off air and drove home. Safely at home I went to defrost to kick in in again, got a thud as the clutch engaged, and it burped out a cloud of refrigerant from the side of the compressor.
It then worked a little better for a while, but now only kicks in again if I go to defrost.
So I may have 2 problems or 1 -- could be that my controls are not working well, and/or it could just be my compressor is failing.
Its a Santech kit I put in 6 years ago from Autozone. Maybe 6 years is the life of a Santech compressor.
Definitely, the serpentine belt bounces more on the idler pully when the AC clutch is engaged via turning on the defrost. Suggests some bindings or resistance in the compressor when engaged.
Need a new compressor for sure. So, supposedly I have a lifetime limited warranty from Autozone -- but the same kit is over 200% higher in cost from them now (over $500 when I paid just over $200 in August of 2017).
May look elsewhere.
Anyone else have to re-do AC after 6 years?