Anybody know why I have heat only @ the highest setting on my digital control?

Once i drop it down 1 or 2 degrees it gets super cold.

There is no gradual decline or incline in temp.

??

Thanks in advance.

 

Probably the cabin temperature sensor is bad. You need to run the hvac self diagnostic to see. But first make sure that the small air intake grille in the dash is not blocked.

self diagnostic procedure

starts on page 70

http://boredmder.com/FSMs/Nissan/Maxima/1998/HA.pdf