“I replaced every single
part in this system, and the new compressor failed,” (or) “It still
won’t cool.” Many technicians can say, with real conviction, that
they’ve replaced everything, or did everything “by the book.”
Sure, a problem may recur
because one of the replaced parts was defective or the wrong part. The
wrong part could be a cheap compressor, but we often find parts that
bolt up in place of others, but are functionally different.
Example: following a
front-end collision, a 2005 condenser was installed on a 2006 Chevy
Impala 5.3-liter V-8 (“looked the same” and bolted up). Blame the body
shop because (hopefully) no A/C pro should miss the fact that the 2005
Impalas have a separate receiver-dryer, and 2006 models have the
condenser with integrated receiver (“modulator” with desiccant bag
built in). Side item: the Impala (a transverse front-drive car these
days) didn’t get the V-8 until 2006; only V-6s were used.
However, no one replaces EVERY single part on the A/C, no matter how
catastrophic the compressor failure. And the parts replaced often
aren’t the repeat-failure root cause. There’s something else the
technician didn’t replace or do, or repair properly. Or he did
something that’s worked before on other systems, but doesn’t work this
time, and he’s surprised, or in denial—“nah, it wasn’t THAT. I’ve
never had a problem with THAT before. THAT’S great stuff.