i have a 96 nissan quest and im having heating issues, sometimes it blows hot air and most of the time it blows cold air. the temp gauge is working fine though... and the anitfreeze is full any suggestions?

Might have air in the heater core. You'll need to bleed it out. You might be able to get it out by running the car with the radiator cap off and the car parked facing uphill on a slight incline. Have the heat turned on while bleeding.

This information/experience came from working with a similar issue on an 02 Van. You most likely have air in the heater core. The core is higher than the engine or radiator. To fix your van's malfunction, raise the front of the vehicle 22 inches in the air from the ground to the bottom of the front air dam. Open the radiator cap (when cold) and fill the radiator up with coolant. Start the engine and continue to add coolant until full. Replace the cap and let the vehicle back down. Make sure you keep the radiator overflow tank full of fluid as the engine and core will probably gradually use some of this fluid also. Hope this helps to solve your problem.
Modified by blockmachining at 7:17 PM 12/27/2009