A hot car in the summer is all but unbearable, especially in very hot climates.
Many things can go wrong with a car or truck A/C system, with the most common being that the unit has a low refrigerant charge.
Once all other possible problems are eliminated, recharging a system is an easy task that almost any home DIY mechanic can do.
Of course, if in doubt, take it to a professional.
Refrigerant recharging kits are readily available that anyone can buy to get their A/C back to blowing cold air.
What Refrigerant Does your Car or Truck Use?
There are three types of refrigerant that vehicles use R12, R134a and R1234yf.
R12 is mainly used in older cars and trucks built before 1994.
R134a is used on most vehicles built from 1994 until the mid 2010s.
R1234yf is used on most newer vehicles and was in about 90 percent of new US models by 2021.
If your vehicle was built between 1995 and 2014, it more than likely uses R134a as R12 was banned due to environmental concerns.
For those who have a vehicle built close to the 1995 date, a sticker should be located on the system somewhere that displays the refrigerant used, or alternatively, it can be looked up online.
Note: Any vehicle built from about 2015 to 2021 could have either type and needs a label check under the hood.
Note: R1234yf systems use different service fittings and an R134a kit will not hook up to them.
Never mix R134a and R1234yf or top off one type with the other.
DIY R1234yf cans are sold but cost a lot more than R134a.
How to Recharge a Car or Truck Air Conditioner
- A recharge kit is needed. In this example, we are using the Interdynamics Arctic Freeze Recharging Kit, but there are many R134a kit options.
- Be sure to wear gloves and eye protection in case of any accidents.
- A 14oz can of R-134a is in the kit, and the top plastic cap needs to be removed.
- The cap is screwed onto the bottle.
- A/C systems have two tubing lines for High Pressure and Low Pressure.
- Next, start the engine and turn the air conditioning to Max Cool with the fan set to the highest setting.
- Check and be sure the compressor is running as it needs to be running to get a charge into the system. You will know if it is running as it will be spinning.
- Attach the hose from the bottle to the Low Side port.
- The gauge will show what the charge state of the system is. Keep in mind overcharging a system can possibly damage components and the unit will not work properly.
- To add more refrigerant, squeeze the trigger on the can.
- Once the unit is charged, remove the hose and replace the cap. The unit should now be fully charged.
The Arctic Freeze gauge and hose is sold on its own and works with R134a cans that have a self-sealing top.
Note: Skip the propane or hydrocarbon cans sold as R134a replacements because EPA does not allow them in car A/C systems.
Note: Liquid refrigerant can freeze skin and eyes on contact.
It is against EPA rules to vent refrigerant into the air on purpose.
Locate the Low Side port on the A/C system.
The Low side port will always be on the larger diameter tubing.
Note: The low side cap is usually marked L and the kit coupler only fits that port.
Never hook the can to the high side port because the pressure there can burst the can.
When adding refrigerant into the system, do it slowly and check the gauge to get the right amount into the system.
The gauge will show Green for Low, Blue for Filled, Yellow for Alert, and Red for an Overcharge.
Note: Most gauge makers call for about 25 to 45 psi on the low side when it is 65 to 75 degrees outside.
The target goes up on hotter days to about 50 to 55 psi at 95 degrees.
Check the chart that came with your gauge and do not go past the top of the range.
Summary
Charging a vehicle’s air conditioning system is an easy task that most any backyard mechanic can do.
When working on any car problem, be sure to wear the correct protective gear.
Before charging a unit, be sure of what the problem is. If it is only a slow leak, then a cheap DIY charge may be a good temporary solution.
Note: An empty system or one that goes warm again in a few weeks has a leak that needs to be found.
UV dye or a shop leak test will find it, and an empty system needs to be pulled into a vacuum before it is recharged.
Note: Many kits contain stop leak, and it can clog small A/C passages and shop recovery machines.
Also, before charging, be sure the compressor is running, as that may point to another problem.