Do you know how to recharge your car AC system? Did you even know that you needed to? Just like anything else on your vehicle, the air conditioning system can break down over time due to good old wear and tear.
If your car isn’t cooling off as it should, it can wreck your summer road trips. Unless you’re heading out to one of these cooler destinations, you might want to get that cool air flowing again.
Instead of investing in a new AC or paying for extensive repairs, first try recharging the system. A batch of fresh refrigerant can make all the difference. If you’re a dedicated DIYer, you might even be able to change it yourself following these steps.
How Does AC Work in a Car?
The air-conditioning system in a car works by manipulating refrigerant between a liquid and a gaseous state. As the refrigerant changes states, it absorbs heat and humidity from the vehicle and allows the system to give off cool, dry air.
To change the refrigerant between a liquid and a gaseous state, the air-conditioning system works to control pressure and temperature.
How Do You Know When Your Car’s Air Conditioning Needs to Be Charged?
In the event that your car’s air conditioning develops a leak, there are a few telltale signs it could benefit from a boost or need repairs:
- The air conditioner is blowing warm air: The first and easiest way to tell if your car’s air conditioning needs to be charged is if it is blowing warm air out of the interior vents. Since the system works by circulating the pressurized refrigerant, less refrigerant will affect its performance.
- The A/C clutch will not engage: When your car’s A/C is fully operational, you will occasionally hear a slight “click” as the A/C clutch engages. However, if you don’t hear the click (from outside the vehicle), it’s probably because the system isn’t working properly and the refrigerant level is low.
- Visible Leaks: Another easy way to tell if your car’s air conditioning needs to be charged or repaired is when you notice thin, greasy puddles on the floor under your car’s engine bay. If the refrigerant is leaking that badly, you must have it serviced.
Now follow these steps to learn how to charge the car’s air conditioner.
Here’s How to charge Auto AC
Anyone who can follow the instructions can charge the car’s air conditioner. Get your goggles and gloves, grab the refrigerant and fixing hose, and let’s get cold!
#1. Find the Low Side Port.
Next, find the low side port of your A/C system. This will be the barb on the larger tube between the compressor (mounted to the engine and with a belt) and the evaporator (a large aluminum can). If in doubt, consult your service manual or local parts store.
#2. Attach Can of Refrigerant.
Screw the dispenser hose and gauge onto the can of refrigerant. Attach to the low side port by pulling back the outer slip ring, pushing it on and releasing the ring.
Next, start the engine, turn the A/C system on max and check the gauge reading.
The compressor clutch should be engaged and the front of the compressor spinning.
If the pressure is lower than 20 psi and the compressor is not engaged, then dispense refrigerant until the clutch engages. Be sure to shake the can first and every 3-4 seconds later.
#3. Continue Dispensing Refrigerant.
Consult the pressure chart in the refrigerant instructions for the proper system pressure. Continue dispensing refrigerant and rechecking the pressure until the desired level is reached.
In my case, with an ambient temperature of 85 degrees, the instructions called for 45-55 psi. Be sure not to over-pressurize the system. If you feel like the can is empty, flip it over to dispense the remaining oil before removing.
#4. Check for Minor Leaks.
If you bought UV dye as part of the kit, check the system for minor leaks so repairs can be made if necessary. Use the UV pen and examine all valves and junction points in the system.
In my case, I found a small spot where the front A/C feeds refrigerant to the rear A/C under the car.
How Often to Recharge Your Car Air Conditioner?
Recharging the AC on a car is not a regular maintenance item on your car’s manufacturer-recommended maintenance schedule. In theory, the system is sealed, and you should never need to do this.
In practice, however, rubber seals dry up and wear out, and refrigerant slowly evaporates over time, leaving too little in the system for the air conditioner to work effectively.
Other components can fail as well, but attempting a recharge is the first thing you should try, particularly since this is a cheap and easy DIY fix and often all it needs to start working again.
How Much Does It Cost to Recharge Car AC?
These costs are generally not that expensive when considering that this maintenance also extends the life of your compressor, keeping your air conditioning performing optimally season after season.
A professional AC recharge cost ranges from $150 – $300 on average depending on the make and model of your vehicle.
Due to refrigerant losses that occur over time, this service is one that should be added to your vehicle maintenance schedule. It is recommended that this service be performed on a vehicle every 100,000 miles or so.
You can save on your this cost by going the DIY route and recharging your car’s AC, in which case you can expect to pay $40-60 for a proper recharge kit.
This may seem like a real savings over taking the car into the shop and possibly more convenient, but before proceeding with the DIY alternative, it’s important to understand exactly what’s going on when you get an AC service at a shop, vs doing the job yourself.
When Should You Recharge Your AC?
The first signs of an AC compressor not functioning properly will be air flow that is warmer than usual when electing the coolest of settings. Air conditioning systems can lose refrigerant in very small doses over time, but rapid leaks are a cause for concern.
It’s important to note, that while simply grabbing a can of refrigerant and charging your system will certainly get your AC working again, it’s vital that you pay attention to the proper pressure of the system and don’t over-charge.
Some AC systems, especially newer R-1234yf systems do not take a large amount of refrigerant – some as little as 6oz – and over-charging the system can lead to catastrophic failure.
If you have successfully charged the system yet weeks later, you feel warm air again, you probably have a leak.
Air conditioning systems have several connections in which these leaks can occur, so regular maintenance can help you avoid costly repairs in the future while maintaining optimal cooling throughout the life of your vehicle.
It is expected that at 100,000 miles, your air conditioning system will require servicing. At the first sign of your air conditioning performance not up to par, you should be aware that an AC recharge is probably warranted with an accompanying AC recharge cost.