2001 Jeep Cherokee cold air

I had the same problem with my 2001 Jeep Grand Cherokee. The problem turned out to a broken blend door pin. The blend doors control the cold air [via AC] and hot air [via heater] mixture to provide the selected temperature setting. When the blend door pin breaks, the default position is down which consequently blocks the hot air section. This means your AC works fine, but the heater, at best, will blow ambient [outside] air temperature. The dealership, of course, can fix this problem, but as I'm sure you can imagine, it would be very costly. I purchased a kit online and installed it in my driveway.