Charging R-410A Refrigerant into an Air Conditioner! Pressures, Temps, Tips!

in this hvacr training video we're going over how to add refrigerant into a or for tonight air conditioning system so i'm going to show you step by step what happens with the pressures with the temperatures and we use a sub cooling and superheat method in order to check the refrigerant charge so i'm going to show you how to know when it's fully charged so i'll show you all those steps and if you want to learn about the methods that we use out in the field we have these quick reference cards that you can use when you're checking the charge and adding refrigerant and also when you're troubleshooting we also have a pt chart there and if you want to learn about preparation of an air conditioning system and checking the charge and troubleshooting make sure you check out our book the refrigerant charging service procedures for air conditioning over our website at ac service tech dot com now we're gonna get started [Music] we're going to connect our manifold gauge set and hoses to this system so we have our red hose gets connected to our small liquid line and the blue hose which is the low pressure side gets connected to the vapor line and so we're going to make sure first is that we have our valves in the off position these are manual low loss valves so we check that first and make sure our gauge set is closed at the handles and is closed at the connections right here and so what we're going to do first is we are going to take off our port caps right here and in this case we just have regular port caps but you may have your locking cap so you make sure that you have the proper key in order to get those off and so what i'm going to do is i'm going to connect right in here push this forward and once you get it screwed slightly on that's when you want to do it fairly quickly because you may have refrigerant that comes out if you try to do it slow it also has to do with the condition of your rubber grommets right here the newer the rubber grommets the better and quicker you're going to be able to connect so right there so now we're tightened and so we're reading our pressures and what we're going to do is we need to purge the air out of the lines here here and here in order to do that while the system's off we're going to open up both handles at the same time and that's going to allow the refrigerant to push through and push the air over into this hose and so that's that's what we're going to do first we're going to open both at the same time then we're going to purge our air out right here alright so now we have refrigerant and all three hoses you may not see a flash of liquid because this system is not running and so what we want to do is we're going to connect this onto our bottle right here and it is going to be hard to tell you know if you got all of the air out but it doesn't take a whole heck of a lot of time in order to get the air out of the hoses so you don't want to just leave it open for a very long time but you also don't want to get air into your system so what we're going to do is we're going to open up this valve here and we want to get the air out here and we're going to close that down so now we have our tank attached to this hose and we want to shut our valves right here so then we can open up our tank we can do that at the bottom of the the tank right here this tank is actually upside down right now and that's because right here this tank has liquid in the bottom and vapor at the top and we want to have liquid exiting this tank and so it has to come out to 50 50 mixture of r32 and r125 in order for the refrigerant or for tonight to stay intact and so now at this point we're going to turn our scale on as well so we want to make sure that we zero that out now if you were to purge the air out of these hoses while the system is running you would do the vapor side first and then you do the liquid side after that and then you would see a flash coming out of the liquid line as a verification that only uh liquid is now in the hoses and obviously you don't want to let the flash occur too long because then refrigerant would escape to the atmosphere you're trying to minimize refrigerant loss of the atmosphere because that's bad for the ozone so all right so now we're ready there and what we're going to do next is we're going to attach our temp sensors onto the lines here and here and so i'll go ahead and do that get reset and then we'll turn this system on by the way we also already checked the airflow inside this unit is a two-ton system we're blowing about 751 cfm's that's cubic feet per minute and so you need 400 cfms for every ton so we have right about the proper amount of airflow the filter is checked and the indoor unit has a piston metering device and so we're going to be using the superheat method so we can use our quick reference cards here in order to check the charge uh i already know that this system is low on refrigerant but we're going to turn the system on check the charge and then add refrigerant into the system now we're going to push the disconnect in and turn the unit on so presently it is about 75 degrees outside and about 73 degrees inside the building and so what we want to do is we want to let this system run for about at least three minutes before converting this pressure on the low side to saturated temperature so this outer ring reads pressure and this is the low pressure side connected to the large vapor line and this is the high pressure side right here connected to the red liquid hose on the small liquid line and so if we if we measure this pressure right here and we bring it into the r4 tonight saturated temperature you can see right now it's below 10 degrees and so we need to let this system run for a few minutes before getting an accurate reading but we already see it's it's kind of low so that's very likely a issue and anytime that our saturated temperature is below 32 degrees it's either one of three things it could be low refrigerant charge low indoor air flow or liquid line restriction and so we can use our our troubleshooting cards in order to determine what the problem is over here we have our temp uh meter right here t1 is measuring our liquid line temp and it says 81 degrees and if we go over to t2 we measure 51 degrees on this vapor line right now we are going to have to wait just a few minutes in order to let the system cycle through before we actually check the total superheat with this gauge right here and our temperature on the large vapor line in order to determine our charge level we need to wait about 10 to 15 minutes so our first three minutes is to make sure our saturated temperature gets up above 32 degrees if it is and it's around 40 degrees or so then we can wait the additional 10-15 minutes to check the charge we may not have enough refrigerant though to even be above 32 degrees so you know this is a testing unit uh we don't have a leak on this if you did have a leak you would want to search for that leak and try to fix that leak before adding refrigerant because if you add refrigerant or a lot of refrigerant basically you can just leak right back out again and so the customer will just be calling a couple days later saying hey you know my unit's low in refrigerant again we have a problem so you want to try to find and fix a leak but in this case i actually recovered refrigerant in order to do this video another thing i wanted to point out is you can use your test probes or quick connect test gauges and you could add refrigerant in into the low side gauge using a t like this so you don't have to use a manifold gauge setting hoses you could just use quick connect test gauges in a tee and you could have a hose from here right over to your bottle so that's another alternative that you can do as well so right now what we have is on t2 we have a temperature of about 65 degrees and we have a pressure it's still fluctuating up and down up and down but right now it's about 80 psi we bring that into about 21 degrees as a saturated temperature for r410a you take 65 minus 21 and you're left with 40 right about 44 degrees of superheat once again you can see it's fluctuating you got to give it a little bit of time let's head to the indoor unit and i just want to show you i've got a tent meter there we're measuring our delta t inside right now we're measuring our delta t so i'm doing this to just kind of give you an indication of what's happening as we add refrigerant into the system but our t1 is in the return duct and it's measuring 71 degrees we want to make sure that it's at least 70 degrees inside the building before checking the charge and then it doesn't drop down below as you're adding refrigerant uh too low and you see on t2 is in the supply duct right here and we're measuring 60 about 60 degrees so our delta t from the return to the supply is only 10 degrees right now and so if you have real high humidity and an accurate charge you may have 16 or 18 degree delta t a lot of times we're shooting for 18 to 21 degrees as a delta t uh if the humidity is low then and you have an accurate charge then you may be able to attain that 18 to 21 but i'm just giving this as a reference right now our unit's only been running for maybe about two two and a half minutes our system's been running for about three minutes now and our saturated temperature on the low pressure gauge is has not risen above 32 degrees so what that means is that the temperature of the refrigerant in the indoor coil is below 32 degrees and that means that it's going to be frosting it's going to be freezing any humidity that crosses that indoor coil so what we do is we take our pressure which looks to be about 84 and we bring that into the saturated temperature of our fortinet on the inner ring and it reads about 22 degrees so we take our temperature on the suction line at 68 minus 22 and we're left with a super heat of 46 degrees and so just so you know i'm just going to come over to my liquid line real quick and we're measuring 80 degrees on this we see a saturated temperature in the middle of the outdoor unit of 80 degrees so if we have 80 minus 80 or actually about 81 81 minus 81 we have zero degrees of sub cooling we need to add refrigerant no sub cooling high super heat that means we add refrigerant so here we go we're going to add a little bit in at a time and as we add our refrigerant in our scale is going to show how much we're adding in we're going to change our units because right now we're on kg now we're measuring in ounces so we have 0.6 ounces in we're going to add a little bit of refrigerant at a time because it's coming out of the bottle as a liquid and we're putting it into the vapor side and it's going right into the vapor compressor you don't want saturated refrigerant going into the vapor compressor saturated means liquid and vapor at the same time it's going to end up slugging the compressor so you don't want to just open this handle and just let it let it fly in there you want to do a little at a time you can also use a quick charge adapter and that would flash the refrigerant as it goes into the system so we know we're very low once again i i recovered the refrigerant out of this system it's not a leak we're not just weighing a ton of refrigerant into this system and it's just going to leak out again i'm just doing this to show you what happens so right now on our vapor line you see what happens we're at about 60 degrees right now and every time that we add refrigerant in you're going to have a fluctuation in your in your temperature over here it's going to go down then up and down again and that's going to happen and so you're going to need to keep adding refrigerant in we certainly need to be above 32 degrees the fact that we have no sub cooling and a high superheat means that we're low on refrigerant if we had the correct amount of sub points that we had like 10 degrees or 12 degrees of sub cooling and we had a low saturated temperature it's likely a liquid line restriction problem so we're just going to keep adding refrigerant we have about 4.6 ounces in right now if you ever have to add a lot of refrigerant into a system say like a pound or two pounds or something like that you may want to turn the outdoor unit off and let the indoor quill fan run for a little bit just in case at any point the evaporator coil was frozen so this whole time the evaporator coil would have been below 32 degrees and so this this tells you the saturated temperature in the middle of the indoor coil so at that coil you should have liquid and vapor throughout that coil it's absorbing heat from the indoor air that's how the air conditioning system works the refrigerant absorbs heat at the indoor unit and the refrigerant travels to the outdoor unit where it then rejects the heat there and it does that with the help of an increase in in pressure and temperature at the compressor and a pressure reduction device at the metering device now what will happen is if you add too much refrigerant in at one time you'll hear a compressor noise change and that's a indication that you're doing it too fast you're adding refrigerant in too quickly so right now we added eight ounces in we're just now getting above 32 degrees as our saturated temperature what's happening is our refrigerant is in air conditioning mode this is just an air conditioning system our liquid refrigerant is heading this way away from the unit and heading to the indoor metering device and then our our low pressure vapor is heading back this way into the compressor so it's coming this way and exiting here and so this coil back here is where the liquid would condense into a sub cooled liquid refrigerant i'm going to keep adding our refrigerant you see our super heat hasn't really increased much or i'm sorry decreased we as we add refrigerant our superheat so it's a temperature uh change between here and here that is our superheat so as we add refrigerant our superheat should lower and our sub coin should raise up and so if we were to check our sub coin right now we still really don't have much of any sub point we have 83 degrees here and 83 degrees here and so we still really don't have much of any sub cooling so this system was very low on refrigerant we've got 10 ounces in here so far and so 16 ounces per pound our vapor saturated temperature at least for the moment is about 38 degrees so it's really not about pressures you know people ask hey what's the operating pressure for r4 tonight well it doesn't matter as much as temperatures do the whole system works on temperature so it's a saturated temperature at the indoor coil your temperature on the vapor line here and your saturated temperature in the middle of this coil here and your temperature where it exits at so the saturated temperature of the refrigerant out here should be around say 10 degrees higher than where it is where it exits right here that's called the subcoin and the super heat what that is is you should have saturated refrigerant in the indoor coil and as it absorbs heat it phase changes into a completely vapor state and after it does that by absorbing heat from the indoor air it turns into a vapor and then increases in temperature and so if we're reading the saturated temperature here on this gauge at say 37 degrees and we have a temperature in the line of 60 degrees and that means we have about 20 23 degrees of superheat so that superheat is lower now we got this above 32 degrees and so now we want to go back to the indoor unit we want to check to see what our our indoor wet bulb temperature is and so we're going to let this thing run for just a little bit out here and we did add our 12 ounces but now we need to determine what our target super heat needs to be so let's go ahead and do that our delta t has risen to 16.5 degrees and so if we were to look at our t2 measurement we got 53 degree air coming out of our supply duct and so our delta t is certainly getting higher now we do have low humidity in this building and so now we're going to look at the indoor wet bulb temperature at the return so right here we're measuring 54 degrees as our indoor wet bulb temperature now we need to take our outdoor drywall temperature in order to determine what our target superheat needs to be so now that we have our indoor wet bulb temperature of 55 degrees is between 54 and 56 our outdoor temperature is 72 and so what we want to do is we want to so 72 71 and a half we're going to go with say 70 to bring that over it's between seven and ten degrees as our target superheat and so let's just go with say eight eight degrees is our target superheat and so if we were to take a temperature right here of 61 degrees minus 35 degrees we're left with about say 26 degrees of superheat and so what we're going to do is we're going to add some more refrigerant in just a little at a time so you know our indoor temperature is kind of low right now so it's about 70 degrees inside we're just going to continue to add refrigerant the whole point of me telling you that is that this saturated temperature is not going to be real high it's not going to be 45 degree saturated temperature it's going to be kind of low and that's because of the indoor heat load is low it's only about 70 degrees inside right now so it's on the lower end of when we would want to even be checking the charge and it's kind of low outside as well there's not much of a heat load it's about 72 degrees outside you can see our temperature lowered as we add refrigerant in you see a small increase in our uh high side pressure as we add this refrigerant in it's very windy out here so hopefully that doesn't mess up the sound too bad for you so we're about 14 ounces so we're going to let this sit for just a little bit and we're just going to continue to monitor this so if our target superheat is eight degrees we want to now calculate what our actual superheat is so we got 59 minus 35 and we have about uh was that 24 degrees of superheat so we're going to continue to add a little bit of refrigerant right now our scale isn't quite moving as much just because of the wind being applied to the side of the tank which is kind of funny but anyway we're at about 15 ounces right now so you always want to zero your scale out before you start charging so you know exactly how much you're you're adding in now you don't want to just have the bottle weight there you want to you want to have it very clear so if you just open up this handle and you add a lot of liquid refrigerant right into the system you know you're going to be damaging the compressor uh it's called slugging the compressor and so you don't want that to happen you also don't want to over charge this system by putting up putting in too much refrigerant right off the bat because what will happen is if you don't have any superheat at all like no superheat that means you have liquid refrigerant traveling right back into the compressor so that is the saturated refrigerant that's at the indoor coil it never gets to change into a vapor and you just have saturated refrigerant going right into the vapor compressor and that will damage it so you kind of have to do this slowly at the same time our indoor temperature now is about 69 degrees so it is lower so we want to try to get this done kind of quickly right as you add your refrigerant the temperature is going to go down but then it might come up a little bit it'll then kind of come back down we just added a little bit of refrigerant so i want to give it a sec just to kind of cycle through the system before i check the charge again our delta t is now 17.2 so that's looking really good right now and we're going to check our indoor wet bulb temperature and we're measuring 53.9 so 54 degrees as an indoor weapon temperature our indoor wet bulb temperature was 54 degrees and so we have a outdoor temperature of 73 degrees as you can see we're getting off of the chart now and so we're we're reaching the point in which we can't really check the charge anymore because the indoor dry bulb temperature is so low and the indoor temperature's so low but we know that we still need to get to about seven degrees of superheat so we we're just gonna shoot for about seven six degrees of superheat right now as our target and so you can take our temperature on our vapor line and it's reading 47 degrees minus about 37 degrees and we have about 10 degrees of superheat right now so so we're very close so that's that's about it and so what i'm going to do at this point is we have liquid in our refrigerant hose and so what i'm going to do is i'm going to close off the bottle right now so we're going to shut this right here and we'll close our bottle down now this unit up on the reading plate says it was factory charged with 3.7 pounds and so you see that we had taken out just about one pound of refrigerant out of the system the line set length is short so it has about the factory charge in there right now again so 3.7 or so pounds and so let me just check this super heat one more time so we got 48 minus 37 so we have about 11 degrees of superheat with our hose shot over here i'll just show you i'm going to disconnect right here so we still have liquid refrigerant in this hose so what i can do is i can charge this liquid refrigerant into the system a little at a time and that will lower our superheat down now i'm going to give that a second i'm going to check this charge again but i don't want to over charge it either so even though i have extra refrigerant in this hose i don't want to put it into the system because i don't want there to be basically no no superheat at all because that would be dangerous to the system our target superheat already needs to be pretty low so which is about seven degrees so we don't want to shoot to a lower superheat than that so let's just check what our sub coin is just out of curiosity and we have 85 degrees there's a saturated temperature here 85 minus about 78 so we have seven degrees of sub coin so you noticed as we added refrigerant our pressure here increased and our saturated temperature increased our liquid line temperature lowered so that spread gave us sub cooling and that's our the lowering of the liquid temperature over here on this small liquid line and so what we have over here is we have our super heat and so right now we have 45 degrees and 35 so we're at about 10 degrees of superheat still so we can go ahead and add a little bit more of the refrigerant that's in here into the system we can also shut our scale off at this point so we're gonna go ahead and open this up again the biggest thing is we don't want to overcharge the system so right now we just have vapor left in this hose so that's good so we can go ahead and shut that we'll give it a sec and we're going to monitor what our superheat is so right now we are accurately charged we have 37 degrees here and we've got 43 or 44 degrees here so we have about six or seven degrees of superheat and so i've been monitoring this for about three four minutes now and even though these change just a little bit we still remain at about six seven degrees of super heat so where we would normally do a disconnect procedure where we shut this red hose off right here at this valve and disconnect and then try to charge that refrigerant into the low side i'm not going to do that because i don't want to end up overcharging this system so all i'm going to do now is i'm just going to disconnect from here and here and and that's going to be it so what i'm going to do to disconnect is while the system's running i'm just going to shut off this and i'm going to disconnect the low pressure side and what you can do on this side you have high pressure sub-cool liquid refrigerant so you could disconnect now or you could shut the system off let the pressure lower and then go ahead and disconnect right here at this point now we're just going to add our bubbly protector over to the the end ports and then after that if there's no bubbles that form we can blow that out and go ahead and put our valve caps on if this area is an accessible area where the public can get to you got to put your locking caps on and so now let's look inside at our delta t we're at the indoor unit and our delta t is 17 degrees between the return and the supply air this system has a fixed orifice so we had to use the total super heat method and you really want to check your total superheat in order to know what your charge level is you don't want to just go by your delta t so i hope this video helped and if you want to learn more about hvac make sure you check out our book the refrigerant charging and service procedures for air conditioning so we go over the preparation of a system for refrigerant right there in say chapter 10 we go over the vacuum steps we go over recovery we go over checking the charge so we have a different scenarios right here we have the superheat chart so technicians use that in the field as well as our quick reference cards and so these hold up really well outside so you can check all that out over acservicetech.com ac book we also have a bunch of free resources at our website such as the calculators the quizzes the quick tips the articles so make sure you check all those out at easyservicetech.com hope you enjoyed yourself and we'll see you next time at ac service tech channel

Channel: AC Service Tech LLC

Views: 1,413,525

Keywords: acservicetech, repair, maintenance, how to, fix, hvac, hvacr, how do you, test, ac, service, tech, check, measure, read, superheat, subcooling, refrigerant, procedure, voltage, charging, temp, multimeter, freon, r-410a, r410a, r410, 410a, electronic scale, scale, digital scale, gauges, manifold, st4, refrigerant charging, refrigerant hose, port, cap, air conditioner, system, unit, low charge

Id: qpXZhTRPIXc

Length: 27min 55sec (1675 seconds)

Published: Sat Jul 03 2021