My 2002 4 runner with only 63,ooo miles overheats when it gets hot and I have to sit in traffic. Sometimes it takes a long while, sometimes it happens in just 15 minutes. Faster with the ac on.

1 - Coolant good, changed at 50,000-- no fulid loss

2 - good fluid flow

3 - no obvious bebris clogging condenser or radiator coils

My thinking is that I either have a bad fan clutch, or the radiator coils need to be cleaned. I have some AC mechanic coil cleaning chemical that will clean them so good they’ll shine. Spray on , let sit 10 minutes and pressure wash off.

If this does not do the trick, how the heck do you test a fan clutch?

With engine hot, turn the engine off, open the hood and try spinning the fan by hand. If the fan spins the fan clutch is defective.


A pressure test of the coolant system and radiator cap may reveal issues.