Hi everyone.

I have a 2002 Altima 2.5s, and I recently noticed that turning the thermostat knob has no effect on the air temperature coming from the vents. It has been set on cold all summer so I have no idea when it quit working. It worked fine this past winter when I bought it. Now that it is getting cooler out I have been trying to use the defrost, but only air-conditioned cold air is coming out. It is getting a little uncomfortable!

Before I take it to a professional, is there something I can check? Thank you for any and all advice/ideas.

-BP

blend door isnt operating.

I would check your coolant level .. It is possibly that you may have a air pocket. Air pockets will give you no heat. Do Not check Coolant Level After driving the Vech !! anyway back to what i was saying. IT could be as simple as Bleeding the coolant system , witch could be tricky being these motors have 2 thermostats. Nissan usually Requires you lift the front of the Car up so Air would travel to the front of the vech so it could be bleed out of the radiator . The way you can tell if this is your problem is by checking fluid level at the radiator and running the Vech at 3k rpms for 3 to 5 mins after vech has been warmed up and see if you feel a Temp Change in the vents , Meaning getting warm, then cold after a few mins after you let off the gas.
If thats the case , it's an air pocket. If not then you need to check controller for proper operation. Gl..

Thanks Guys! I will give those suggestions a try.

-BP

2 possible causes.
1. cable fell off or broke off from the back of the knob(happened to me)
2. look at the middle console next to the drivers right foot for that same cable going into the black plastic box. The bracket is possibly loose and turning the knob has no effect. ( thats how I broke the back of the knob).
Make sure the cable is working propperly.

taking the console is preety easy just pull on the plastic cover. take out the radio, youre there.
good luck