It’s important to check the operation of the car heater and auto air conditioner because these are big ticket 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 the air conditioner on. Unless it’s very cold outside (below 32 F), the air conditioner compressor should click on immediately.
The air conditioner compressor should stay on for at least 10 seconds. If the compressor seems to click on and off every 3 seconds, the system is probably low in Freon. Being low is a relatively simple problem to fix. Why it’s low is almost always a more expensive problem. Within a few seconds chilled air should blow from the vents.
If you do not feel the cool air, it is possible that the auto air conditioner is not functioning. In addition to the fact that the auto air conditioning problem might be very expensive to repair, this also points to the possibility of the car being involved in a front end collision.
Check the heater.
Try all of the heater fan speeds. It is not uncommon for some of the speeds to have failed.
A big problem with heaters is a leaking heater core. A leaking heater core only gets worse with time and is very expensive to repair. With the heater on, if you smell moist air coming from the vents with an antifreeze smell, beware. If windows become foggy, this is an indication of a leaking heater core.
This is a relatively easy problem to spot and a very expensive problem to repair. I would skip this car and move on to the next one. Yes, there is always a next one. A little extra work now will provide years of benefits.