Hi, all of the sudden my 98 maxima se auto climate ac is acting weird, it'll blow hot air when I set ac to cold, meaning around 75 down, and it'll blow cold air if I set ac to hot, anything above 80. Anyone has any suggestions how it happens?

 

Probably your in-cabin temperature sensor is bad, or you have blocked the air intake spot on your dash for the sensor.

Run the built in diagnostic for the auto climate controls. It should indicate what is the problem.

Start on page 70 - http://boredmder.com/FSMs/Nissan/Maxima/1998/HA.pdf