Added Freon to AC system with can upside down, how to fix?

I added a can of Freon to my car air conditioning system. You are supposed to hold the can with the valve on the top so that the “gas” at the top of the can is drawn into the AC system. I held the can with the valve on the bottom so the liquid freon went into the system instead of the gas. Now the system does not get cold enough. How can I fix this?

Even if you hold the can upside down and liquid freon goes into the system it will turn into a gas before it gets to the compressor. If the system doesn’t cool then it might still be low on freon. Does the compressor run?

It might also be that the system has some other problem, was never low, and is now overcharged. In that case, adding yet another can would be very bad. Refrigerant should never be added without checking high and low pressures and comparing that to the correct chart.

The position of the can does not make much difference other than speed…

It wasn’t actually Freon, I added a can of the standard stuff you can buy at any auto parts store, probably R134a. I used a guage that came with the can and I attached it to whichever line per the instructions, I think it was the low pressure line. The compressor runs normally, the AC seems to work normally, just not cold enough. Hopefully nothing was damaged. If I have a shop evacuate the system and charge it correctly do you think that might fix the problem? At the same time they can check for leaks. CarX will do this for $40.

Adding refrigerant to the low side as a liquid can slug the compressor, damaging it. You need to to take it to someone who has the proper equipment so it can be determined if the compressor was damaged.


This is one more reason I recommend against these “DIY” a/c charge kits. I have tried them before and have never gotten so much as decent results. Hopefully, no damage was done, but don’t try to do this yourself again. This is a job that requires the right equipment and expertise to do correctly, and the right equipment cannot be found in Walmart’s automotive section for $20.

R134 is freon.

Freon is DuPont’s trade name for their R12 refrigerant. R-134a is not Freon.


Refrigerant constantly changes properties throughout the system so theres nothing you can do with it now. The only danger of introducing refrigerant in its liquid form is like what Tester said, it will lug the compressor. Also, liquid refrigerant going through the compressor will literally wash the oil out of the compressor damaging it. I would do what Tester said and have an AC tech look at it to see whether you damaged it.


Thanks for all your help. I am going to take it to a shop and have it looked at and evacuated and recharged and tested for leaks. Next time, I will buy some equipment, I found the equipment would be too expensive that is why I didn’t buy any. Can anyone recommend equipment, guages, etc., that are not too expensive, or should I just leave this AC stuff for the shop. I prefer to do my own work, when possible, or when I can save money, but if it requires a lot of expensive equipment, then it doesn’t save money.

What year is the car? You said you added 134-a. Is the car old enough to still run on R12? If so, 134 isn’t going to work without swapping out some parts.

It drives me crazy when it is called Freon. But I think we’re into one of those things where a specific brand name product is becoming the generic word for a whole set of things - like aspirin was originally Bayer’s name but is now just the generic word. It would be bad in this case but I suppose its so hard (and expensive) to get R12 that it wouldn’t matter much.

I still think everyone should just call it “refrigerant.”

It’s old but it was converted to R134a by a previous owner (I think!), but now that you mention it, I better check, that could be the problem, but don’t the fittings for R134a only fit R134a? Or, do those fittings also handlge R12? The car is a 1994 Jeep Cherokee.

That’s the safest thing to do money wise and safety wise. Something as seemingly unimportant as a slow radiator fan can push the high side pressure up to ballistic levels even without over charging the system. And with the DIY charger attached to the low side if the high pressure safety switch turns the clutch off the low side pressure will quickly climb in excess of 100 psi and cause the can to explode. I hate being a stuck record on this subject but…

You cannot connect to a R-134a system with R12 connectors, and you cannot connect to a R12 system with R-134a connectors.


The '94 was probably on 134 since the beginning, but if you got the 134a fitting connected then you have almost certainly are on 134. The R12 fittings were different.

Charging the system with the can upside down is adding liquid instead of gas. This can blow the valves out of the compressor and I’m in agreement with Tester.

An even worse appropriation of a name for refrigerant is calling it “coolant”. Ugh.

Whatever. R134, R12 it’s all called freon whether it’s duponts trade name or not.

Not by those who are in the refrigeration repair business. And actually know what they’re talking about.


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