“My A/C started blowing hot air! What should I do?”
So, you’re stuck in a hot car, feeling sweaty and wishing your A/C would work again. What should you do?
If you look around at auto parts stores, or ask around your circle of friends; you’ll probably get told to recharge your A/C system. If you look online, you’ll probably be told to do the same, or worse, to purchase some sort of ‘fix in a can’.
During the hot season, our store locations hear the words “My air conditioner doesn’t blow cold air anymore..” quite a bit. Unfortunately, there can be many, many more causes for this type of A/C failure than simple loss of Freon. We encounter plenty of times where it isn’t that simple to fix your car A/C.
To explain this properly, you need to understand some basic background on how your air conditioner works. Whether in a home, car, or even a window unit, HVAC (Heat, Ventilation and Air Conditioning) units work on the same basic principals.
Remember High School Chemistry? When a gas transitions from high pressure, to low pressure, a temperature drop occurs as the gas turns to a liquid (think water vapor condensing into water). Now you have a cold “liquid”, run that “liquid” through a radiator, blow air across it and you have cold air.
To accomplish this, you need some special parts; not just Freon. You’ll need a compressor, which cannot be run continuously, or it will pump things up too high; some way of forcing the gas to change pressure states; a radiator to blow air over for cooling; and then another to heat that cold “liquid” back up into a gas to be run back through the compressor.
You’ll also need some sort of fan for the blowing air, and something to direct the air flow off of the cold radiator, for when you don’t want cold air! That’s a lot of mechanical and electrical parts; and all of them have to function to keep your A/C blowing frosty cool and delicious.
The actual gas in the system is just one small part… so why is it always assumed that when the system of all those moving parts stops, the gas is to blame?
All too often, the question gets asked, “How do I fix it when my A/C blows hot air?” and the answer that is given is ‘Stop Leak’, or ‘AC-PRO’ etc.
There are numerous “fixes-in-a-can” that are for sale out there, for the often wrong assumption of a low Freon condition. The problem lies in that system of moving parts.
Let us assume that you DO have a leak in your A/C, and that is the only reason your HVAC started blowing warm air. The sealants in these canned A/C products, are designed to harden when exposed to oxygen. If your A/C system was sealed, there would be no oxygen inside… Only Freon.
The problem arises, that when you have a leak, air gets INTO the A/C system, which is what creates the issue with lack of cooling, then when the sealants are exposed to that air, they harden…. just the same as they do at the site of the leak.
Now you have pieces of solid sealant flowing around inside this system of moving parts, and it is only a matter of time until you create some sort of part failure. Now instead of just a leak, you have failed parts you have to replace as well.
If you don’t have a leak – you still have that sealant inside the system, waiting to be exposed to oxygen, and you have also now over-charged that system with Freon, creating a NEW problem other than whatever had been happening before.
This makes your mechanic’s job that much more complicated, when he or she is trying to determine the failure in your A/C. Plus, when they connect their machinery to your A/C lines to measure and gauge the performance of your car’s air conditioner; their machine will now be contaminated, and spread that same sealant contamination to every other vehicle they service.
There are all sorts of reasons your air conditioning system may have stopped working, including:
- Electrical issues in the controls for the compressor
- Just low enough Freon that the A/C cannot drop to a low pressure on a really hot day
- Airflow over the evaporator core is restricted by a dirty air filter
- An improper AC repair was performed in the past and has caused new parts to fail
- Computer issues causing the temperature controls in the vehicle to malfunction
- Failed electronic switches or safety cutoffs in the HVAC electronics.
- Failed or faulty internal or external fan units
When it comes to properly repairing your air conditioner in your truck or car. You should have it professionally checked, and diagnosed – before spending your hard earned money on remedies that might actually cause more problems and damage than you can afford.