[brcidd]

All GM W-cars wait on a/c head pressure to turn on the fan(s) at 175 psi the primary fan comes on, and at about 250 head the secondary comes on....

What is engine temp when primary comes on? 3/4 on a gage means little... perhaps you don't allow it to get hot enough to run secondary fan..a tech I scan tool wil command fans on.. or by jumping the ALDL connector (as I recall) will energize fans... what happens when you jumper the relays...

you are NOT overheating until you are above 250 or so--or your dash gage is in the red...engines by design can run hotter these days..primary fans usually energize at 227 as viewed on Tech I, and secondarys are probably 235+ or so...

I think there is a good chance your system is okay- you just haven't found out how it works yet...I see this all the time folks driving when it gets warm out- not yet using A/C (no fans) but tell me their engine is overheating because it runs hotter than normal--yet when I hook up to them- and command them on, they work just fine..when they use the a/c, it runs normal, because the fan(s) are on....they have a hard time believing me--I always ask-what their definition of overheating is-- mine is coolant boiling out into the burp tank....they say that doesn't happen-- then I say that is not overheating...