How to Charge an Air Conditioner That is Low On Freon ~ AC 101


All right, today I’m going to be showing you
how to charge up a unit that’s low on freon. This particular one, when I feel this suction
line, the low side line, it’s not even cool. It’s room temperature here, so we’re low on
freon. Got my standard set of gauges here, and I’ve
calibrated my gauges so that they show zero. And I got my refrigerant can of freon on top
of the unit. So I’m going to go ahead and get set up here and show you how to hook this
up. What we’re going to do is we’re going to take
the blue low side line, make sure both of our valves are off here. Because of the low
side lines, I’ll go ahead and hook up my line here. Now, you always want to wear gloves
anytime that you’re working with refrigerant to protect yourself from frostbite. And now looking up at my gauges, I can see
it’s only at 20, which is too low. And the first thing we want to do, the thing that’s
the worst for an air conditioning unit, is get moisture on the line. And moisture’s obviously
contained in the air, so we want to bleed any air out of the line. And the way we do
that– this is called a de minimis release, and we’re going to purge any air from the
line by cracking the valve right here and let a little bit of the freon out to purge
the line. So now there’s no air in the system. The high side line right here, we’re going
to loosen the schrader valve cap, again, listening for any hissing or anything coming out there.
And also looking for any oily residue spots that would indicate that we have a leak there.
So I’m going to hook up my high side line. Which is kind of tricky on this unit, but
that’s OK. Going to lift it up here. And on our high
side, up here at the gauges. We’re going to again release a little bit of refrigerant
to purge that air from the line so that we don’t get air in the lines. Now what we’re looking for on the high side
is ambient temperature plus 30 degrees. So if the temperature is 80 outside– which it’s
not. Today’s supposed to be 113-115 degrees out here in Palm Springs, but right now I’d
say it’s about 105. But look, the moon’s still out, too. But anyway, back to our charging
here. We’re looking for ambient temperature, plus
30. So we want it to be about 135 on the high side. So obviously we’re pretty low here. So our middle line, we’re going to take and
we’re going hook this up to our refrigerant can. I’m going to angle this up so you see
it here. Then we’re going to turn thew refrigerant can on open it up. And again, were going to
come back down to our gauges. We’re going to crack the port here to release the purged
air from the system. Now we’re ready to charge the unit. If we
didn’t purge the air and I opened the line to charge the system, that air is going to
go into the system. And when the moisture in the air mixes with the refrigerant, it’s
going to turn into acid and it’s going to cause us leaks and all sorts of trouble. So
anyway, I purged the line, we’re ready to charge. So I open the line, and you can probably
hear the refrigerant going into the system. Now here I’m feeling the line with my wrists
in the suction line side. I can usually tell by feel when it’s starting to get cold. But
what we’re looking for is for it to flash, when it just flashes really ice cold, and
to charge the unit up. Also, again, we’re looking for ambient plus 30 degrees on the
high side, so this can take a little while. I can show you a few little tricks on charging
the unit up. One way to get it to charge faster is if your compressor’s hot to the touch on
the top here– which this one is, it’s been running low on freon– you can pour a little
cold water on the top of the compressor, being careful not to let it touch the electrical
contacts. Or if you had an ice pack, to put an ice pack on the compressor– that’ll speed
the refrigerant charge. Also another way is having shorter hoses helps.
Sometimes these hoses, they send you with a six foot hose line and that’s going to cause
you to take longer to charge the unit. I like these little short ones. These are three feet–
perfect for me. But obviously, there are some situations where
you need the longer hoses. And some people might disagree with me, but anyway, this is
how I like it. Makes it nice and easy for me. It’s pretty hot out here. I’m going to drink
a little water myself. A little water for me, a little water for the compressor here
to speed things up. You could see it just sizzling off– that’s how hot this compressor
is. It’s just been running low on freon. So we’re only at 110 on the high side, this
is going to take a while. On the low side, looking here at the dials, you’ve got different
color dials. The inside one is purple for R502. And this green ring is what we’re looking
for to match the can of our refrigerant, which is R22.

92 thoughts on “How to Charge an Air Conditioner That is Low On Freon ~ AC 101

  1. this would be a great vid if you muted it and then went back and narrated it. I did learn something though. Thanks

  2. To lanceditzler,

    This one was just a bit low on freon and took about one and a half pounds to reach proper charge of ambient plus thirty degrees on the high side. It was a hundred and five degrees and climbing up on the roof that day. It just makes sense to calculate refrigerant usage by taking a before and after reading with the scale. No need to lug the scale up on the roof.

  3. so you use outside ambient, and not inside ambient? My furnace is in my basement, and the A/C unit is obviously outside…so I would go with outside temp, not what my basement temp is? Thanks, I know its a noob question.

  4. To Pbour, Yes ambient outside temp + 30 on the high side is what your looking for as a general guide. However some systems have design differences. Use your feel and judgement. The suction side line should flash ice cold along the length of the suction line to the compressor. When it cold sweats a little you know your good. The general proofs though are 40 degree temperature at the evaporator coil and fifteen to twenty degree split between air temperatures at an inflow and an outflow register.

  5. ToTheATLAdventure,
    Using quick connect fittings will prevent the refrigerant from going everywhere unless you have a leaking schrader valve. You can see the quick connect in the video with my right hand I am using a quick connect fitting from about 1:01TO 1:16. When you disconnect the quick connect it quickly cuts off refrigerant flow.

  6. To dianemarie909, there are actually quite a bit of different methods and varied schools of thought as to what is the most accurate method. I like to add the gas little by little through the low side or suction side and monitor temperatures and pressures. Some people weigh in refrigerant by calculating manufacturer specs. and adjusting for length of plumbing with the compressor off through just the high side as a liquid and some through both sides.

  7. Informative, but at 48 sec in the video it says the blue gauge is for liquid! I don't see a lot of our maintenance guys purging their lines and is probably the reason we do so many compressor changes and due to overcharging because they only know the "beer can method."

  8. I like to poor a couple cups of water on the compressor when its running too. This helps to cool down the bearings and greatly increases the life of the electrode diffusers inside the valves. allows them to get nice and cool and oils them up. Great Job Jedi. Best Damn video i've seen in a while.

  9. @rsgarnerthree Yikes you are so right. My bad, my bad, my bad. I have done what I could to fix it. Whoops 0:48. The high side is the liquid line and the low side the vapor.

  10. @mrsokla I only learned about the electrode diffusers in trade school last month. I didn't know that keeping them cool makes such a big difference in the service life of this type of equipment. I know that suction line superheat is used for determining heat transfer on the evap and subcooling for the condenser, but that tells nothing about those electrode diffusers. And what the hell is discharge superheat all about?

  11. @eagletek1 Oh Yeahhh, SuperHeat and SubCool the finer things I would like to get into more. More accurate measurements are needed when working with more complex and sensitive equipment and systems. Capillary tube and fixed orifice systems allow for some variance but other advanced systems require more precise charging.

  12. kungfuMaintenance i just curious is that okey if ask you about the comment you say that you add 30 degrees to the ambient that means that the pressure should be 8o + 30 =110 degrees the pressure shuld be 226 degrees? thanks good video

  13. Best way to charge in my opinion is charging through the low side(suction side) while unit is running with vapor only from the tank, keeping an eye on pressures and temperatures. Low side line should flash nice and chilly all the way to the evaporator coil. Look for the 15-20 degree split from an in going to an outgoing register over a time span of twenty minutes.

  14. You cannot charge with a plain bottle through the high side. as the gas will flow into your bottle ! second, when you have to keep recharge your AC. test for leaks first because these installations should never been refilled if proper fitted and no leaks !

  15. I have watched many videos and I am impressed with this one. Most video show purging the supply/suction line but not many show purging the Low and High side. I pay close attention to the tec. when he work on my system and ask questions, but I have never seen them purge the lines. Excellent video.. Thanks for taking the time to share..

  16. This one was R-22 vapor charged. You are right in that charging R-410 application is different depending on your jug of refrigerant and whether it has a dip tube or not determines whether the jug needs to be flipped upside down or not to use liquid. Charging R-410 is still done through the suction side but the short story is it needs to be throttle charged with liquid. Not liquid side only just charged with liquid. R410a is charged as a liquid to prevent the refrigerant blend from separating.

  17. This one had a tiny micro leak which I used a micro leak repair additive to repair (you can see the video I have on it if you like to titled "Air Conditioner How To Super Seal Micro Leak Repair"). It has now been a year and several months since the repair and system is still running great keeping things nice and chilly. No lack of performance. Purging the line sets prior to charging is how to prevent getting moisture into the system.

  18. i have an ac license and i never heard of a micro leak but i do know you can use a leak detector and alot of times the seals leak or shrader valves leak

  19. That could be normal, it could even take longer, it really depends on quite a few factors. Temperature out side that day, temperature inside, cleanliness of coils and filters, how hot the compressor is due to running at a low freon level, amount of freon in the charging cylinder, condition of schrader valves, condition of filter driers, all of these and much more factor in to the speed of the charge. Check my video " Four Ways To Speed Up Refrigerant Charging" for tips on speeding things up.

  20. Yes that is true charging in colder weather takes more time. One way I have found to speeds things up in colder weather is to remove the refrigerant can from the box (which acts as an insulator) and place the jug of freon over the condensor fan so as the fan removes heat from the condensor it blows the heat across the refrigerant can. This recycles the heat energy at the can and speeds up the charge. The box acts as an insulator to the freon can so removing it will allow the can to absorb heat.

  21. thanks for the quick response
    i have tried that also, it makes a mess of water from the condensation lol
    i also heard some people turn the jug sideways to give it a slight amount of liquid though the vapor side(which i know youre not suppose to)
    havent tried it yet though
    anyways i couldnt find your "four ways to speed up charging" video

  22. If you do a quick youtube search "Four Ways To Speed Up Charging" it should come up in the first few selections (at least it did for me).Yes a little bit of condensate rain for a faster charge, not a bad trade in my opinion. I will echo the voices you have heard against tipping the can as it likely will shorten the compressor life by introducing liquid refrigerant to the pistons.

  23. hi , love your videos a quick question?after you purged your lines and began to charge unit , you opened blue knobs on gauges however i didnt see you open high side red knobs at gauges ?did you ?Do you have to open both?

  24. You are right on there. I opened blue suction line only to charge with vapor. No you do not want to open both as this will let liquid refrigerant cross over into the suction line. For charging purposes you only want to open the blue low side suction line. There are other methods of charging done solely through the high side. I prefer charging with vapor through the blue low side as it is easy on the compressor and fairly easy to monitor and adjust. ~ Good questions. Thanks for watching. ~ KFM ~

  25. That actually depends on the size of your system, the temperature at time of charging, and the distance of the line set. These days I prefer to charge by superheat and subcool. I hope to be making more vids on superheat and subcool in the near future.

  26. Most likely it will take between 1/2 to two and a half pounds to increase 10 psi. The line set distance is the plumbing from the outside condensor to the inside air handler and evaporator. See me vid series "How To Charge An Air Conditioner Low On Freon By Superheat and Subcool" for a better explanation of the terms. For good charge your high side on the green dial would show 110 as a less perfect rule of thumb. I mostly go by temperature pressure relationship (SH and SC) rather than weight.

  27. EPA does state that residential a/c with a certain % leak MUST be fixed. If it is low on coolant,if it has a leak or the last man to service this a/c made an incorrect charge. People far too often jump straight to charging a system. In my job we have 5 guys that service the same 443 a/c's thoughout the property. It is go go go all the time. We dont not have time to recover and pressure check every a/c that we think has a leak. A service log sticker is very great idea to place on the condenser!

  28. AC techs need to be prepared for all craziness they will find out in the field. Ready for anything before opening a unit. Loose capacitors like this should be anchored and I have a couple videos showing different methods "How To Secure A Dangling Capacitor", "Plumbers Strap Method" and the "Military Grade Cable Tie Method". As for the gloves they prevent frost bite see me vid "How To Replace Leaking AC Schrader Valve Cores That Leak Freon Refrigerant Charge" for an extreme demonstration why.

  29. Do NOT open the red valve on the gauges. That will allow the high pressure refrigerant into the manifold and then into the refrigerant bottle which could be very dangerous.

  30. I have an evaporator that if freezing up I've changed the filter and cleaned coils would a low charge cause this?

  31. Yes that is very likely. Ideal charge will produce a temperature around 40 degrees plus or minus 5 degrees at the evaporator coil. When the freon is low the temperature at the evaporator coil can go below 32 degrees which as you probably already know is the temperature at which water freezes.

  32. A/C wont blow much cold so I called Gateway A/C repair in El Paso Tx. My Tech comes here Fri………….cant fix it cause its frozen up, Tells my wife to run FAN ONLY till Monday.(HOT weekend here) Comes back Mon and works 3 hrs and tells me he needs a part that he cant get until Tue. Its 85 degrees in here and he leaves. Its 1AM and too hot to sleep.
    This has been going on for a WEEK now. Man Im about TIRED of messing with these guys.

  33. Cool video… Very informative. Not trying to be rude but the text that constantly fills the screen takes away from the content of the video. The Mael font is tough to read, It's kinda like going to a prawn site and being constantly bombarded with pop up ads. 🙂 some nice easy to read txt at the bottom right or left of the screen would be the cat's meow. Peace.

  34. Hi, how much does this service cost if I were to call a tech to come out? My A/C is barely blowing cold air. It does not get below 80 degrees in the house even if the A/C runs for 6 hours.

  35. An initial service call would probably cost about 60 to 100 bucks. Add to that parts or such that may need to be repaired or replaced. If it needed R22 it could be a bit more expensive in price these days as r22 is being phased out which is driving up the cost of the refrigerant. Expect to pay between 30 to 100 per pound of freon average 2.5 ton system holds about 7 lbs. If compressor is not overheating than it is probably no more than 3 pounds if low on freon.

  36. True that all around, these are general rules of thumb, for the general sit u at ion, with general spec i fics, when you understand the gen era l truths it can help you move on to the finer points, such as superheat, subcool, and fin er testing. K no w ledge is some thing to be built up on but always quest ion ed. It starts with evidence, a found at ion, things you can under st and on and than is built up from there. It is constant ly being re proved test ed and adapt ed to further in sight.

  37. Yes this was R-22 and I was charging by vapor through the low side. This takes a tiny bit longer than charging by liquid but is easier on the compressor and also easier to get at time of service measurements of what is going on (superheat and subcool wise). Charging by liquid takes more time for pressures to balance and adjust. R410A should be charged by liquid (can upside down) unless it has a dip tube) because it is a blend and the blend will separate if charged by vapor.

  38. If you go to a service call and the unit has been running for a while and the coil is 20 degrees, first thing you should do is go to thermostat, turn off ac and turn fan from auto to on. Let that run for an hour or longer to defrost the inside coil. Also, check the inside filter, that could have also been the reason for the low temps and frozen coil. Never charge a system with the inside coil frozen, you will not get an accurate charge.

  39. Through the process of "dumping in" one can measure and charge weight of liquid refrigerant on the high side and or low side. This is done with the condensor turned off and waiting an appropriate amount of time before turning the condensor back on.

  40. If your careful, you can charged with liquid in the suction line and it would me much faster then vapor charging…  

  41. you have some good tips to share.  may I suggest that you change your font type?  it's difficult to read and the camera gets shaky as you are trying to show examples of what to do.

  42. Thanks for helping me to challenge bull crap artists.  A good A/C guy is hard to find!  I have been told that I needed to replace whole unit for 5000.  I found ants around the contactor.  I just can't charge my system.  I've fixed everything else.

  43. Hi, I'm a fan of your videos. I may have seen them all but I'd like to suggest an Audio-Technica ATR-3350 lapel microphone so we can hear all the valuable information when you speak. It's only 32 dollars and will make your videos a lot better, because it kills 90% of the background sound.

  44. Where the hell is your refrigerant scale are you serious? You made a video without the scale Parham HACK. let me guess your using the the manifold S pig as the guide. Cough HACK.

  45. Great video. People dont understand how much just a scale can slow you down on a hot day. Hell, in the sumer i try to leave anything i can in my truck or shop.

  46. normally when it takes such a long time to charge the system especially one of those old beast janitrol's it means u have something else going on aswell. could be as simple a dirty evap coil or something as serious as a blockage. the only thing that would make the system take so long to take in freon under normal conditions is a extremely long line set or a long lift on the lines. im sayin you also have a dirty evap on that unit.

  47. At 7:05 the colored diagram really sends home the information about which is the low side line, high side line, and everything else!  super job guy, thanks.  it's too bad it's Saturday, 90 degrees indoors, and you just convinced me that i probably better not mess with my apartment complex's ac unit when i especially don't have a drum of Freon to spare.

  48. Does it matter where the r22 is when filling the unit? Does it need to be above the unit like the video shows, or does it even matter? Can it just be set on a surface near. As long as it is vertical so only gas freon, no liquid going through lines, right?

  49. Red is high side LIQUID blue is low side suction…and vice versa if you have a heat pump in head mode. And if you have a system that low shouldn't you be recovering and checking for leaks in the line set and evap coil? Just saying cause you're not really fixing the problem, just wasting refrigerant.

  50. Do you have turn the HEX shaped valve on the suction line (on the insertion at 2:20 of your video) after you hook up the BLUE hose? My low pressure gauge stays at zero after I hooked up the BLUE hose and turned the system on? I saw you removed the sideway cap of the suction line and hooked up the blue hose to it. But you didn't mention anything about  these HEX shaped valves on top of the suction line next to the cap (now blue hose). I just want to check if my Freon R22 is low because my home central AC (Heat pump) is running but not pumping out any cool air.

  51. Upon taking the cover off that thing first thing you should have done is turn all power off to the system and move that "hanging" capacitor to a safer place! How can that possibly be up to code?

  52. should use SH and SC to get a proper charge if not weighing in proper charge. and look for a leak if its low.

  53. is ambient temperature the general formula to go with?Will the same formula work for r410a? My last question my system can use both r22 or r410a how do I figure what's in my system? Or is the better route to go is to evacuate the system and just fill it with r410a. Thanks for the great video.

  54. How long does it take to charge 2lb of freon of r410 a ? Condenser is 3 tons and just need 2lbs just wanted to know how long does it it take to charge it those 2 lb . Anyone knows ?

  55. probably great valuable information but very poor audio quality….so it is useless. But this guy is probably very knowledgeable about HVAC just very unknowledgeable about making a good video

  56. im getting into the e @/c field n i got calls from people asking me to charge their a/c unites but im starting to learn the process little by little

  57. what you show is improper procedure. That's a good ballpark but you should charge according to superheat and / or subcooling. C'mon you know better!!!

  58. the very first thing you really need to do is clean the coil and change the air filter to get an approximate reading right off the bat then you want to hook your gauges up

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