The air conditioning system in your car is designed to cool down the air in the cabin of your vehicle to keep you comfortable on a hot day. When you only get hot air instead of cold air, it can be frustrating and extremely uncomfortable. In this article, we’re going to look at how your Car’s A/C creates the cold air so you can more accurately diagnose what’s going wrong.
The cool air is created by blowing air from either outside your car, or from the cabin over cold coils. This cools down the air before it gets blown out of the vents into your car to keep you comfortable. Most systems are designed to blow very cold air, between 32 and 40 degrees! These cooling coils, called the evaporator, is where the actual cooling of the air happens. These coils are cooled by cold refrigerant flowing through them.
Most cars today use a refrigerant called R-134a which is a special refrigerant designed to work at the temperatures and pressure standard in a car’s A/C system. As the cold refrigerant passes through the evaporator it absorbs the heat in the air which warms up the refrigerant. This warmer refrigerant now needs to be cooled back down so your A/C system can continue to operate. This is accomplished by first compressing the refrigerant to a high pressure which also heats it up to a high temperature.
This hot refrigerant is then cooled down by running it through the condenser. The condenser is cooled by ambient air in the front of your car just like the coolant in the radiator is cooled. On most cars the condenser is actually in front of the radiator and gets cooled first to make sure your A/C system gives you consistently cool air. This high pressure, now cooled, refrigerant is then allowed to expand quickly as it passes through an orifice or expansion valve. The expansion valve is a simple device that takes advantage of the fact that quickly expanding liquids and gases get cold. The process of liquids and gases getting cold during expansion is a scientific phenomenon you can prove by using an entire can of spray paint in one sitting and seeing how cold the can gets.
Now the cold, low-pressure refrigerant can return to the evaporator to cool it and along with it, more air keeping your car comfortable. There are a few other components in the system like temperature and pressure sensors, hoses and the dryer or accumulator. The dryer is where any moisture is removed from the refrigerant, the refrigerant is filtered to make sure it all enters the compressor as a gas, and the oil for the system is equally distributed through the refrigerant passing through.
If your car’s is blowing hot air then one of these systems isn’t doing its job properly. Since there are two components that require air to be moving through them, the evaporator and the condenser, it is possible one or both of these are clogged and not getting the proper air flow. Check the front of your vehicle for debris, the engine cooling fans for proper operation, and your cabin air filter for debris and dirt. The refrigerant in your system also needs to be able to flow properly through the system. Check your compressor for proper operation, clogs in your system and the proper amount of refrigerant. All of these can be checked by observing the pressures around the system both before and after the compressor and all the other components. This can be done with set of A/C gauges to measure both the high and low pressure sides of your A/C system.
If you find unusually high pressure before any particular components and unexpectedly low pressures after them, there is a good chance there is a clog in that component. If this is the case, you will most likely find the clog in the accumulator or the condenser. If you don’t have a large enough pressure increase across your compressor you may be in need of a new AC compressor. If you have lower than expected pressures on the low pressure side of your system, may simply have a low refrigerant level.
If you do not have enough refrigerant in your car’s A/C system the compressor may not be able to raise the system pressure high enough for the expansion valve to be effective in cooling down the refrigerant. Due to the high pressures of your air conditioning system and the volatile nature of the R-134a refrigerant used, it is not uncommon for some of the refrigerant to leak out over time causing a low pressure condition in your system. If you discover this to be the reason why your A/C is blowing hot air add Red Angel A/C Stop Leak to your vehicle’s air conditioning system to seal any leaks no matter how small they are before you recharge the system.
Red Angel A/C Stop Leak One Shot comes in an easy to use aerosol can that can be installed quickly and easily without any tools and also contains 2.5 ounces of R-134a to help bring your system back up to normal operating pressure.
To learn more about Red Angel A/C Stop Leak Aerosol visit our product information page here: A/C Stop Leak Aerosol
- Advance Auto Parts
- Bennett Auto Supply
- CarQuest Auto parts
- NAPA Auto Parts
- O’Reilly Auto Parts
- Pep Boys
- Fast Track
- Bumper to Bumper Auto Parts Specialists
- S&E Quick Lube Distributer
- DYK Automotive
Pictures provided by: