I have a delta 88 that will not stay cool,i don't know if its as sensor for the fan or the switch.the fans come on automatically when I turn on the air.

The fans only come on when the AC is on..?
I'm no big expert, but it sounds to me like it could possibly be
the coolant temp sensor..
it'* on the vertical portion of the block right under the throttle body
on my '92 3800.. the part wasn't very expensive, as I recall.
Wasn't hard to replace either.
(you may want to wait for other opinions from those with more experience
with these models before you run out & buy a new coolant temp sensor, though..)

if your fans come on thats not the problem, you check to see if you have any refrigerant?