Starting issue

I was having some ac issues. Anytime I would turn
it on the clutch would make noise and the car
would 'overheat'. Also the fan would not turn on. So
we replaced the fan, used, made sure fan worked
too with the battery. Still wouldn't turn on. We
regrounded the wire and checked all the fuses and
relays the best we could, now the car won't start. It
started with a engine power reduced and a check
engine light. So we 'reset the ecm" and those light
went off but now the airbag light is on in the doc
and still no start. Rado come on tho..please help. :(