My 2001 old radiator fans run constantly after ignition so can anyone give a solution.
Make and model? Engine size? Old radiator fans? Does that mean old, as in the age of the fans or does that mean a 2001 Olds?
Did you buy this car new or used? How long have you owned it?
The engine computer will turn the engine cooling fan(s) on for two (or, more) reasons: 1. when the engine coolant temperature sensor indicates that the engine is hot enough; and 2. when the A/C is switched on.
An unintended engine cooling fan(s) turn on can be caused by some electrical problem; such as, a cooling fan relay gets stuck ON; or, a wiring short to power.
It is also frequently done on purpose as an alternative to fixing a bad fan relay. If the OP isn’t the original owner, that is where I would put my money.
Try the temp sensor in the radiator . . change it. Follow the wire from the temp sensor to any relay and either clean or change it . . . I’d change it. The fans are dumb electric motors that turn on when needed, activatyed in some fashion by some device due to a rise in coolant temp. Seems easy enough to figure out. However . . . does the engine overheat despite the fans being on? Could be something else if that’s the case. Rocketman
Doesn’t even have to be done b/c of a bad relay. …I know a few people in hot climates who wire the fans together and then to power, just to battle the summer temps. Their view is, yah, it may put xtra strain on the electrical system… but it beats a possible busted/warped head.
If a sensor wire breaks, the fan will be on. Some cars.
Have you been using the A/C or the defroster?
The fans in most car will be on if the A/C or defroster are in use.