I’m seeing these things in the auto parts stores for about $30. It’s a bottle of freon (or equivalent) and a pressure gauge. You hook it up, read the dial, squeeze the trigger and your a/c is charged. Do these really work? I realize they’re useless if you have a leak, but if all you need is a charge, is this the ticket?
They’re fine if your vehicle was set up to use R134a. If it’s an older vehicle which was designed to use R12 or still contains a partial charge of R12 (which by law must be recovered by a properly certified technician), it requires a system purge and change of the compressor lubricant before the R134a is introduced.
Ultimately, you have a leak, otherwise the system would still be functioning properly, assuming it to have been properly charged by the last service technician.
Do trhey work?
Maybe.
If the system is empty the kid has no provision for evacuating the air out before charging. Air in the system will cause big cooling problems.
if the system has been broken open (for a repair, or busted hose) since there is no way to evacuate, there is no way to get the water out of the system.
Systems today are critical charge systems. A slight over or under charge will effect system performance. With one of these kits you get the entire can or nothing. If you are 5 oz low you get 13 (assuming a 13 oz can of course) if you are 18 low you either get 13 or 26. With A/C refridgerant too much is just as bad as too little (and has the same effect BTW)
So can you refill a system with one?
Yes
Will it be as good as a properly done job at a professional shop?
No likely
I did it a few weeks ago. I had no air conditioning before and pretty good after. It isn’t that difficult although I screwed up a can and wasn’t sure of how much of the replacement to put in. Buy the can and the hose sepertaly. The cans that come with a cheap hose or crappy.
There are a number of possible pitfalls, but if your A/C is cooling poorly because of low refrigerant* (freon) level, this could work to improve it.
Theoretically, the system should not leak at all. In practice, it’s not unusual to have slow seepage, but not have a leak big enough to detect. I generally advise customers that if the system doesn’t need recharging more often than once a year, it’s cheaper to recharge it than to find and fix the leak(s), and if it goes two years or longer between charges, it’s unlikely the leak will be found.
In order to be certain that poor cooling is due to loss of freon, you would need a set of pressure gauges (one for the high side of the system, one for the low, marked in PSI) and some knowledge of the system’s mechanical operation. Otherwise you run the risk of overcharging the system, on top of whatever the real problem is. So there is some risk to the do-it-yourselfer. Be aware.
That said, here are some general indicators:
>Sudden loss of all cooling is not due to low freon, unless it’s from a burst-type leak where the system won’t hold the freon anyway.
>If the A/C compressor clutch does not engage at all, there’s either an electrical problem or the freon level is so low that a recharge won’t help for long, if at all.
>If the cooling effect diminished somewhat gradually over a period of weeks or months, and/or the compressor clutch engages briefly (1-30 seconds) then disengages for a while, repeating this engage/disengage cycle, then it’s pretty likely the system is low and a recharge is called for. If the clutch engages and stays engaged, with no detectable cooling, there’s a mechanical problem.
Now, if you’re going to give it a go, here are some tips:
>Make sure your car is new enough to use R-134a, or has been converted to it.
>MAKE SURE YOU PUT ONLY R-134a INTO IT. Various refrigerant blends and “substitutes” are sold, touting great performance/great price, etc. They brag that they are EPA approved. Don’t use them. EPA approval only means they won’t harm the ozone layer, it does not in any way mean they are suitable, recommended, or approved for the car’s system. Using them voids car manufacturer’s warranties and part manufacturer’s warranties. I’m not going to list all the potential problems, but if you value my expertise, take my advice on this matter. It could save you a bunch of trouble.
>“Leak detector” in the freon is almost certainly a little oil with dye in it. No problem. “Leak sealer” is a little dicier - it’s either benign and useless, or possibly (slightly) effective and potentially harmful. My advice - pass on the “leak sealer” type. Pure 134a is the best bet.
>If the system is low enough to have noticeably poor cooling, it likely needs more than one can - probably two, possibly more. It depends upon the system capacity, which is usually on a sticker under the hood somewhere. It might take up to 90% of capacity to fully recharge it.
>The kit should have adequate instructions for hooking up the charging hose, so I won’t go into that.
>Undercharging (caused by the leakage) results in poor cooling. Overcharging results in poor cooling and possible damage to some system components from the high pressures it produces. The trick is to charge enough to do some good, but not too much, which may do harm. Using a pressure gauge set and a thermometer is the safest way to avoid overcharging, but if you’re careful you can probably get by with just the thermometer. Here’s how:
>The thermometer should be the “dial with a stick” type, placed into the center dash outlet vents. A good working system will typically put out 35-45 degree F air in a closed car with the A/C system on recirculate or max. This can vary depending upon ambient temperature and humidity - another rule of thumb is that 30 degrees below ambient temp is adequate, if not ideal. Before adding any freon, run the car with the A/C on for 5 minutes and note the temperature. Then add one can of freon and give it 5 minutes to stabilize. Again note the temperature. If there’s no improvement in cooling, stop.
>If cooling improved but it’s still not cool enough, add freon in 4 oz. increments (you’ll have to judge this by shaking the can). Allow 5 minutes after each dose, and note the temperature. When a 4 oz. dose gives little or no additional cooling, or if it reaches the 35-40 degree range, stop.
Good luck!
*It’s refrigerant, not coolant. Coolant is in the engine’s cooling system, to keep the engine from melting. Refrigerant is in the A/C system, to keep you cool.
You go, Gary T!
Yea, Gary’s got his freon on.