hello i'm aaron and i'm michael and we are auto eclinic what do we have in the shop today we have a 2005 chevrolet impala customer brought it in and said it just wasn't cooling good enough oh that's no good not as hot as it is right now no all right let's get the ac gauges on it let's find how much freon's in it and let's see what's going on all right let's do it on any ac system to find the service ports just follow your ac lines now you can see back here we can see our low side low side is smaller and of course the line is bigger and we had to follow the lines all the way around and then under the air filter we found our high side if you keep following the lines you will eventually find the low and high side we're going to go and hook up our ac machine but this is going to be the same relevance as just regular ac gauges you don't have to have a machine to do ac it is of course nicer blue is low side and your red is your high side now we're going to look at our static pressures static means not running now you can see here our static pressures they're both about the same low and high we have almost 100 low side and a hair over 100 high side now that's a good sign that tells you a lot of things about the ac system with the static pressure if one side was higher than the other you could have a restriction or the system could be undercharged or overcharged for that matter so this right here tells us we look like we're doing pretty good as far as the static pressures now we're going to crank the car up turn the ac on full blast on recycle and look at our dynamic pressures ac is not coming on with the ac on we have no pressure change because the ac compressor itself is not coming on this could be because it is under charged if the system is too low the compressor will not kick on this is for safety of the compressor and the entire ac system for that matter under pressure or overpressure will prohibit the system from coming off what we're going to do now is go ahead and use our machine to recover whatever freon is in the system so we'll know how much freon we have in the system okay we're done recovering the freon we recovered 1.84 pounds and the system takes about 2.2 pounds so we are a little low now if you don't have a machine i'm going to show you how to check the freon levels once again without a machine we're going to go ahead and put 2.2 pounds in the system and then i'm going to under charge it and then over charge it to show you how to read the gauges let's go ahead and hit charge it wants us to vacuum but we're not going to charge 2 2 0 we're going to crank crank the car and turn the ac system on you can see the free end goes in the low side close the high side then when the compressor kicks on we should see our high pressure rise and then our low pressure drop watch our gauges we can see our high side getting higher and our low side should be dropping right now with the system properly charged we can look at our gauges we see our high side sitting at 200 our low size sitting at 35 psi now remember we are in an air conditioned shop environment and the temperature here in here is about 75 degrees with low humidity now the higher the humidity and the higher the temperature outside the ambient temperature these pressures are both going to rise pressure will directly be influenced by ambient temperature and humidity and as you're driving down the road of course it's really hard to see it with gauges on driving on the road but if you were the gauges would also the pressures would change then as well if this were a normal shop environment ambient temperature would be 90 to 100 degrees we would see more around 250 psi on the high side about 40 on the low side now we're going to go ahead and add an extra half a pound of the system and show you what happens to the pressures see your high side rising and now we're getting higher than where we need to be if we were outside once again we would have hit the 300 psi mark this is not bad for inside but like once we take it outside this is going to the high pressure is going to get much much higher now let's remove a pound so it'll be half a pound undercharged now we can see our low side down here our high side rather down at 150 and our low side we're down below 30. you can see now the system is just under charged so once again we're explaining to you how you can do it without gauges now we're going to charge back the 0.52 we took out you're going to see your high side cut back up now of course you'll want to put a thermostat in the vent and always use your center vent your center vent is the closest to the evaporator and always put it on recycled air because that's going to give you your coolest temperature so center vent recycled air that's where you put your thermostat and if you're getting below 40 degrees driving down the road that is very very good once again you need to be driving down the road to get a full test on it because that is when you're removing the most heat from the condenser and when you remove the heat from that condenser that makes the evaporator that much cooler and makes the ac system work that much more more properly that much better so that gives you a pretty good idea of with a machine or even if you don't have a machine and you're just using cans of freon to check your system and put free onto the system now if you go to your parts place and just buy a can of freon that just reads low pressure gauge that is wrong you need to see both sides of the ac system low and high to understand how it's operating and what's going on you cannot diagnose the system or even properly feel the system unless you're reading both low and high side now we know the system is properly full we feel it it's nice cold air now the customer can be happy for the rest of summer you