My daughter has a 2001 Altima and the a/c cycles on and off. More off than on lately. When compressor clutch is engaged air is cold and works good. When it cycles off clutch disengages and air is hot. I've heard about a pressure switch may be bad. If this is the case, is it located on the receiver/dryer and can it be replaced without losing all the freon?

 

Here are two simple things you can do before you go to an aircon technician:
1. BE SURE TO TURN OFF THE ENGINE. Then check the aircon compressor belt. If it is broken or very loose, your aircon won't get any cooler.
2. Check if the condenser fan and radiator fan are working (NEVER TOUCH THE BLADES). If any one of these fans is not working, your aircon cooling is affected. Check the fuse. If blown out, replace with one of the same rating.
There are other causes of this kind of trouble but are better handled by a technician.