My wife and I bought a 2000 Nissan Maxima about 2 months ago. When we bought the car the ac didn't work but the heat did. I tried to recharge the system but of course it didn't work. One day about a week later my wife switched the lever to cold and hit the ac button all of a sudden we have ac. Unfortunately we can not get the heat to come back on Fortunately winters over but we still need the defroster on those chilly mornings. Is this a problem with the controls in the car or is it something else. Please help if u have any light on my problem before i spend 200 dollars for the control panel.

 

The way these cars switch from heat to cooling is by routing the air through the heater core or bypassing the heater core. The temperature control lever sends a voltage to a small electric motor that moves a door inside the air ducts to route the air flow one direction or the other.

Your problem could be any of the parts involved. The control panel is a possibility but you should check the motor and the connecting link between the motor and the air mix door.

See page 178 in the heating section of the service manual for a diagnostic procedure (link below).

http://boredmder.com/FSMs/Nissan/Maxima/2000.5/HA.pdf

The air mix door motor is located under the dash, about dead center, just above the ECU which is screwed onto the floor.

If you can't diagnose electrical problems, then you do have a problem. All you can do is guess and throw money at it and buy parts until you get the right one. A junk yard is you friend for this type.