My blower motor on my heater goes on and off

Have you checked the fuses? If the fuses all check out then I would look at the Blower Motor Resistor as it is a common issue in this generation of Kia.

You can try cleaning the contacts and making sure it is plugged in all the way, but typically they need replaced. It is located on the passenger side behind/under the glovebox.

The OEM Part Number for this resistor is 0K08A-61R20S but since the Rio, Rio5, Sportage, Rondo, Spectra, and Spectra5 all use this part it is very easy to find an aftermarket one from an online retailer.

The resistor should have two screws and then just unplug, then you swap in the new one and screw it back in. I have included a picture from a 2009 Kia Rondo (that I found on Google, not my image) that shows the location of the resistor, yours should be in a similar location.

https://www.kia-forums.com/attachments/b...

Please do note that I cannot promise that this is the fix to your issue without more information, but based on past experience and what information was provided it could be the issue.