Skill related

efficacy
(n)
EFF-i-cǝ-see
Meaning

power to produce a desired effect; effectiveness; potency

1st Sample Sentence

Many medicines will not work properly unless you actually believe in their efficacy.

Root

e ex (out, away)#virtus (manliness, excellence, potency, efficacy) (Latin)

Mnemonics

effic (EFFICIENT)+AC (Y). so just check out if your AC has the efficiency to PRODUCE DESIRED cooling.