Ick & water Temp

I noticed some 3-4 white spots on one of my fish today. I have had
this fish for 6-7 months but in another tank. I put this fish in my
tank a week ago. I think this case of ich maybe caused by the tank
temp.

I also think the tank temp maybe on the high side. The temp cam be
between 79-82

Questions.

1.Can a rise and fall of the tank temp of 3-4 degrees cause ich? I
limited the time on my lighting 4-8hrs (Fish only) so it does not
raise the temp anymore. I dont think a chiller is neccessary but
want to get an opion from some more experienced reefers.

Do I need a chiller? I live in orange county Ca so the temp in the
house gets hot but usually between 80-90 all the time.