The windows and cabin of your vehicle can generate a lot of heat when it’s left in direct sunlight. The exterior metal cabinets in vehicles such as roof will allow substantial energy of the sun to get into your vehicle likewise the windows unless you are using a windshade to surpress that which is not ultimate solution.

AC blowing hot air will catch you at a surprise because it is normal for the AC to take 45seconds to 2minutes before it start circulating but in case of hot air, you will be amazed it is over 30minutes and all you have is the hot air. Believe it or not sudden bad AC can make you have a bad day
Before you really get frustrated and consider paying huge to the vehicle mechanic. We will like to consider some options for you that might be the cause of your vehicle AC blowing hot air

These are our DIY checks anyone can follow:

1. Bad condenser

2. Leakage of Freon (The chemical component that cools your car)

3. Bad cooling fans

As the name implies, all it does is to cool the hot refrigerant back to average temperature of the surrounding environment. This is called Ambient temperature (ABM) and a safe range is between 65F and 75F. Your condenser is mounted on the front of your vehicle and it is just like a radiator. Since the condenser is mounted at the front of your vehicle, it can get blocked by all kinds of dirts in the road ranging from bottles to plastic bags, cans and the likes. A quick check and removal of these unwanted items may return your air conditioning to normal operation.

Remember since your condenser is at the front of your vehicle that makes it prone to sharp objects on the road like nails, bottles or other hard objects that may puncture it. Most of these punctures are large because they are not detected sooner and in the long run will only have you replacing it to be the only solution. They often are mounted to your vehicle’s frame with just a few bolts, only have 2 refrigerant lines which should be easy to remove, and are easily accessible since they are at the front of your vehicle.

Similarly, you may have a low refrigerant situation due to other causes like loose connections, freon leak (The chemical component that keeps your car cool), old hoses or the simple escape of refrigerant over time. These small leaks can cause your air conditioning system to stop blowing cold air.

The last easy to fix problem you may have with your air condition system in your vehicle is a broken cooling fan. The condenser can only cool the refrigerant if it has air moving over it. Over time this cooling fan may become worn out and stop working. It also may blow a fuse or become blocked by dirts. It is advisable you dont check the cooling fan without being insulated due to electric discharge

Source : http://motorfixer.com/why-is-my-car-blowing-hot-air/