I have a 1978 Toyota Hiace that the cooling fan has stopped working in. Any suggestions?

engine cooling fan motor spinning too slow
faulty thermostatic switch
it may have a relay in the engine bay cluster

interior cooling fan has a relay

air con system fault or out of gas
the switch has worn
or the fan motor itself is worn out

if it has a conventional fan driven by the belt , replace the viscous fan hub ( fan clutch)
if electric fans . fuses, relays and water coolant temp sensor to be checked
if the over heating occurs at stop lights , slow moving traffic, hard pulls in low gears , and you have a viscous fan hub , it will be the hub

you changed the thermo switch and relays and it didnt fix it
did you test the fan motor itself

the fuse box cover should have a fuse layout diagram
engine cooling fan

look for a 30 amp fuse

they usually near the fan relays

is the air con cooling fan working with air con on
and engine running

Have you checked for coolant loss or leakage ? If OK then check water temp sensor, both itself and its fuse/wiring. Red.

cooling fan not running.check for faulty cooling fan relay or fuse.cooling fan fan should be running when you turn on AC.hotwire cooling fan make sure cooling fan motor okay.

may be the motor to the cooling fan.

The fan also comes on when the AC is engaged. The problem could be in the AC. Try to unplug ac relays to see if the fan will turn off.

What happens when you leave the relay out? Your fan control module may have a shott.

if the water in your radiator or reservoir is boiling means your cars engine auxilliary cooling fan is not perfectly working enough to dissipate heat inside the radiator( heat exchanger) check cooling fan if its silicone oil filled if its rotating free and no resistance then remove fan and refill silicone oil/ if its equiped with electric fan then fan motor is busted

check your sensor that controls the cooling fans.may need to be replaced.