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Charging your a/c

i just had to charge the a/c using the 134a.i put in 19 oz. it calls for 2.2 lbs. it working fine i know you can over charge the ac unit.still have a can left but worried about overcharging it. the gauge i bought with the 134a is not i was going to keep it were it is. how can i check the amount of 134a in the car.also it seems like r.12 was alot cooler and lasted longer ? i made sure the gauge i was using stayed below 50 as it was in the instruction

Did you just convert this system from R12 to R134a ?

And if you did, did you purge the circuit of R12 and oil (including the compressor) ?

R12 is cooler than R134a and runs at a lower pressure, but it doesn’t ‘last longer’ if you are losing refrigerant you need to run a leak test.

As usual the mantra “Make, model, year” comes to mind.

it is a 2002 montecarlo ss.and it allready had 134a when i bought it new. i really dont think their is a leak .i use a/c all the time in the summer the car is black and so is the leather it get pretty hot in that car. i got 43.500 miles on it. i have the car serviced on a regular bacis at the dealer. i had the extend warranty .wich they wanted to put in parts that i did not need .they work off commision. how do i test it?

There is a leak.

If you have to add freon to the system to get it to work that means there is a leak.

Ah, so the car never was R12 refrigerant, that clarifies things.

Well, as rrhoff said, if you’re adding refrigerant, you have a leak. A leak test should highlight the leak unless it’s compressor seals which you probably won’t be able see.

As far as correct refrigerant weight is concerned, there isn’t anything you can do there without the equipment. Professional equipment charges the AC system by weight but you don’t have access to that equipment and therefore can only charge by low circuit pressure. If your AC drier has a sightglass the usual ‘kentucky windage’ method is to add refrigerant until you can only see 1 or 2 small bubbles in the sightglass. This allows for a small amount of refrigerant expansion during operation. Under / over charging the system will degrade AC performance of course.

the only reason i put freon in is that it was not cool enough. so it is possible i have a small leak.the freon i put in over a month ago is stll cool.i know their is a can to stop leaks but hesitante about putting it in. Should i just keep a eye on it and see what happens since it probally is a small leak? or is their something i can do to replace the seals or is it expensive to repair
?or ad freon as need.?to tell you the truth i dont no to much about the ac unit.and the cost to replace a seal i guess is expensive. or the seal . any info would be helpfull thanks for yor anwser rob

Yea. They don’t consume the refrigerant so if it comes up short, there is a leak. If you have a very small leak, it may be some time before you are low again. When you next show up short, that would be a good time to take it to a shop and let them use their tools to find and fix the leak.

If you have access to an A.C. vacuum pump used only for R-134-A, you can evacuate the whole system. After you’ve gotten the vacuum reading down to or near where the A.C. charging/evacuation procedures book tells you, keep the vacuum pump operating. Are the gauges rising and then falling? If the needles on the vacuum gauge aren’t staying stable, you absolutely, definitely have a leak. A further check is to turn the vacuum pump off. Watch the needles on the gauge. If they are steadily rising from a vacuum towards positive pressure, you definitely have a leak. Fix the leak. Use an R-134-A leak detector. After you have fixed the leak, then you will have to evacuate the system again. A system under vacuum that is leaking sucks in contaminants (air, moisture, fine dust, etc.), through the leak(s).

Auto A.C. systems are checked for proper charge by either using a sight glass near the accumulator or by reading the Hi and Lo pressures on the gauges. When I run into any system with a sight glass, I use the glass during initial charging, but I always go by the pressures on the gauges. Sight glasses are designed to give you a quick peek to see if you have enough charge to operate the system. I go one step further in that I also incorporate a thermistor vacuum gauge to absolutely check that all contaminants are out of the system before I re-charge.

If I now have you thoroughly confused, rrhoff, it’s time for you to take it in to an A.C. shop. Unless you have all of the equipment and knowledge to perform this, you’ll be chasing your tail trying to figure it out. Some places sell leak detection dyes that show you where your leaks are. I have never used the dye method but I know others who have. I’ve been told that for the most part, the dye works pretty well. I just personally choose to depend on my quality Imperial gauge sets. They’re pricey, but they work darned well.

You should have two gauges on a gauge manifold- type holder. One checks the Lo side (low pressure), the other checks the Hi side (High pressure). Are you telling us that you have only one gauge hooked up to the system? You need both a low pressure and a separate high pressure gauge to properly check your A.C. system out. Some pressures on auto A.C. systems can exceed 250 p.s.i. A.C. gauge hoses are also high-pressure hoses. If you use anything but high-pressure hoses, does KABOOM! ring a bell? Refrigerants are very dangerous to handle. Don’t get any into your eyes, on your skin, and don’t inhale it. That stuff is extremely cold and will screw you up big time if you don’t know how to handle it properly. PLEASE! Safety first! Absolutely make sure that you know the difference between the Lo side and Hi side ports. A.C. is very technical and only trained, experienced persons should work on these systems.

thanks for the great advice.their are two gauges on one came with the can of just like you said i"m going to have the mechanic test the a/c unit i dont have a good gauge or the experince.better off having them do a vacum test and the dye test.this way i know for sure it is done correctly.thanks again for your help.i learned more about the a/c unit.their is alot of great advice and “KABOOM” DOES RING A BELLin my pocket book also.thanks again rob

May I crrect your terminology? You didn’t put in Freon. Freon is R12. You put in R134A.

Actually Freon is a DuPont a trade name for its older refrigerants including R22. DuPonts trade name for its newer none ozone depleting refrigerants is Suva. Now how many people you know say its low on Suva.

You will never hear it in a real World shop environment,it’s called FREON,134-A,or R-12,techs know what we mean,as a group that is.