So I got this weird issue with my car, the 2 vents on the left side(middle left, door left) only blow hot air, the other two from the middle to the right door only blow cold. I've adjusted the duel temps every which way and let them run but nothing changes.

 

What year is your car? 97-98 are different from 99-00. You might have a bad blend door motor or ecc control unit. You could try setting both temps on full hot for a minute, then both on full cold for a minute - then return to you requested temp - If that does not help -

To calibrate a 97-98 uses this procedure ( with the old volvo scan tool, or equivalent ) 99+ uses VIDA

 

Thanks for the suggestion, I have a 2000. So I attempted that and now sadly both vents are now stuck blowing only cold lol. Progress non the less but not so good for the winter months ahead 😀