Kia's fan doesn't work unless I hit a bump

I’ve got a problem with my 98 Kia Sephia. The fan for the AC/Heater won’t work unless I hit a bump while driving. Once it comes on it will stay on as long as I keep the car running, but if I turn it off, the fan usually will not work again until I hit a bump. The problem seems to not be as severe on really hot days.

Any suggestions

The fan motor is driven through the contacts of a relay energized when the fan switch is turned to one of the positions. This sounds like contact corrosion.

The location of the relay should be shown in a repair manual from the parts store, or the local dealership can tell you where it is.


[b]The next time the fan fails to run, while at a stop, reach over to the passenger side of the dash, and give the top of the dash a sharp blow with the side of you fist. If the fan starts working, replace the fan motor.


Probably a loose connection somewhere.
Is the thermostat digital (with buttons and a LCD) or analog (with a dial)? If it’s digital, how many speeds are there? Do you hear any clicking when the speed is changed?
If the thermostat is digital with much more than 3 or 4 speeds and does not click when the speed is changed, the motor is electronically commutated, which means it uses transistors instead of relays for control.