what's a cooling fan bypass?

what's a cooling fan bypass?

i was towed to the shop because of overheating. there was a high/low fan speed error code, and it's 8V instead of 12V, so the repair shop put in a bypass on the cooling fan. now, the fan starts without the engine starting and is always running at a high speed. is this as a problem of the bypass?

Welcome to Automotive Forums. The cooling fan operates from a temperature sending unit that sends a signal to the computer which in turn operates the high or low speed of the fan through the relay. When the fan is operating correctly it can come on at any time without the engine running and will continue to run until the temperature is brought down. I don't know what they did so it's hard to say what's going on. I'll go out on a limb and say they wired the fan to operate whenever the key was in the ON position regardless of whether the engine was running or not. I don't see any problem with that as long as the fan shuts down when the key is turned off. The fan is supposed to come on whenever the AC is on and that doesn't cause any problems so I'd say it will probably be all right as long as it is bypassed using the existing relay. If not it could cause some wires to get hot or melt. The cooling fan uses a 40 amp fuse so it has quite a draw. Anybody else? What do you think? Would it wear the fan out prematurely?