So, it's the middle of summer and all of a sudden the air coming out of your vans isn't cold. Your air conditioner simply stopped working? Of course, if you still have air flowing out of your vents, but it just isn't as cold as it is supposed to be, your problem might not be that difficult to fix. At the same time, if air has simply stopped flowing, it could just mean that your fan is somehow disconnected or broken. If you are lucky, this could be another problem that is quite easy to fix. It is really hard to tell until you actually diagnose your issue.
Checking the Heat Pump
If you have airflow, but no cold air, you need to target the heat pump. Your compressor could have failed, or your heat pump could have somehow simply lost power. Depending on the design of your system, it could be possible that your air is still flowing even if your heat pump is completely powered off.
Walk outside next your heat pump while the AC is turned on. It is a very loud unit, so you should have no problem determining whether or not it is running. The same can be done with your air handler. If your air handler is not making any noise, it could simply be disconnected or the power switch could be off. This could mean that the air handler is not pumping air into your ducts. In the best case scenario, you will simply need to reset your breaker box so that you can restore the power to your major appliances. The worst case is probably that your heat pump or a air handler is completely broken and needs to be replaced.
However, the most likely scenario is that there is just one component inside your heat pump air handler needs to be replaced. For example, you might need to replace the capacitor inside your air handler or the compressor inside your heat pump.
Since these issues are never cut and dry, your best bet might just be to call professional if you can't figure it out yourself. Don't mess with any electrical or gas components inside your major appliances.
Contact a residential air conditioning service for further help. Although there will be an expense, in the long run you will save a lot of time and stress when it comes to diagnosing and repairing your issues.