It is important to check the operation of the car heater and car air conditioner because these are expensive items to repair. You REALLY miss them when you need them and they don't work.

To check the air conditioning, start the engine and let it warm up for a few minutes. Turn on the air conditioner. Unless it's freezing outside (less than 32 F), the air conditioning compressor should click immediately.

The air conditioning compressor must stay on for at least 10 seconds. If the compressor seems to turn on and off every 3 seconds, the system is likely low on Freon. Being low is a relatively simple problem to solve. Why it is low is almost always a more expensive problem. In a few seconds, cool air should come out of the vents.

If you don't feel the cold air, the automatic air conditioner may not be working. In addition to the fact that the car air conditioning problem can be very expensive to repair, this also points to the possibility of the car being involved in a frontal collision.

Check the heater.
Test all heater fan speeds. It is not uncommon for some of the speeds to have failed.

A big problem with heaters is a leak in the heater core. A leaky heater core only gets worse over time and is very expensive to repair. With the heater on, if you smell humid air coming from the vents with the smell of antifreeze, be careful. If the windows fog up, this is an indication of a heater core leak.

This is a relatively easy problem to detect and very expensive to repair. I would skip this car and move on to the next one. Yes, there is always one next. A little extra work now will provide years of benefits for more information click here

Author's Bio: 

Used vehicle inspection; Automatic heating and air conditioning