Rick's Free Auto Repair Advice

Recharge AC

How to recharge you car’s AC yourself with a kit

If you follow the instructions carefully, you can recharge AC systems yourself with a DIY kit.

So it’s summer and your A/C isn’t as cold as last year. Simple, just throw in a can of refrigerant, right? WRONG! Unlike the older R-12 freon, R-134a refrigerant has very little tolerance for either over or undercharging. Put in too much and you’ll actually DECREASE the cooling. How much is too much? You’re not going to like this—but the tolerance is only 1-2 OUNCES!

The majority of DIY’ers add too much refrigerant. How do you know how much to add? It’s very difficult. That’s why the pros empty the system and start with a fresh charge. But since you’ve already paid for your charging kit, here’s the poor man’s way to recharge.

Start by buying a probe thermometer. Many pro auto parts and restaurant supply houses stores sell them. Roll up the windows and turn the A/C on maximum and recycle. Insert the thermometer into the center vents on your dash and let the A/C run until the thermometer stops moving down. Then start adding refrigerant SLOWLY. If you have a small postal scale, use that to measure how much you’re adding. Try to add only 2 ounces at a time. Keep checking the thermometer.

On a 90° day, the absolute best you can hope for is a 41° discharge temp from the dash vents. If you can get yours down in the 50° range you’ll be doing well. If adding additional refrigerant doesn’t lower the temp, STOP adding refrigerant! More is not better!


© 2012 Rick Muscoplat

Posted on by Rick Muscoplat

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