You do not mention the year but my 1999 Villager has 3 relays & 3 fuses and a heat sensor switch. If all that works check the fan motor. All I did to check the motor was disconnect the power cable at the fan housing and and use an ohm meter to find the ground lead on Cable ( one lead to engine ground then other lead to each cable lead, the one that shows closest to zero will be the ground)then put 12 volts from corresponding lead on motor and to one of the other motor leads , one should be low speed the other high speed. There might be a different sensor I'm waiting for a manual to find out. Also check the connection terminal on temp switch mine was almost cut in two. Are you experiencing overheating problems?
Radiator cap
Could be a faulty thermostat switch in the radiator !!
you may have an overcooling problem. check your thermostat and temperature switch. the thermostat regulates fluid in and out of the radiator, and the switch tells the fans to come on to cool the engine.
A radiator cap would not cause a leak! However, if the radiator cap is holding pressure, other weak parts could signal issues in need of attention.
I would suspect a clog in the radiator.
to add to this, a big YES,on the radiator cap .the radiator cap needs to be specific pressure rating. radiator caps do wear out. also the cheapest fix to start It is doubtful a radiator cap would cause a car to overheat. Common overheating causes are insufficient coolant, leaking coolant (into or out of your engine), faulty thermostat, blown cooling fan fuse, faulty fan temperature switch ( sender ), faulty fan, or a faulty fan relay.
radiator cap
It's supposed to run, even with the key off until the radiator is cool. If it never stops you've probably got a bad temp. sensor switch.
A leaking radiator hose would NOT cause this to happen, you have 2 problems with this vehicle.
Check valve in radiator cap malfunction, replace radiator cap.
Because it would cause the universe to explode
They get old and become weak.