These are the Parts and Tools I Recommend: Basic R-134A Gauge Set- amzn.to/3efy9qz Dial Thermometer- amzn.to/3ehnUlp As an Amazon Associate I earn from qualifying purchases.
Great video, very well done. I have a 2004 F150 5.4l that will not send power to the relay powering the AC coil. When applying 12 volts to the relay all is well and the system does a great job of cooling and the pressures are right where they should be according to the various charts for temp and humidity levels. How do I prove the issue is the PMC? Or should I be looking in a different direction.
Hey my guy, I'm trying to program a USED Abs module into an 07 sport trac. I've done it with both an autel and FMP, still get a code 2477 for configuration. Have been told that for this particular module (7a2z2c219e) that the old data can not be over written and I am just wasting my time (repeatedly). Hoping you can confirm this. Many thanks
I once overcharged the ac in my car causing it to cycle on and of really fast when I started to accelerate. I could feel the car shuttering from it. Took some refrigerant out and it worked fine again
I was taught this by a HVAC tech. He told me under charge and over charge will trip the pressure switches. I vacuumed down my cooling system and charged it after I was having problems. He pulled out almost an extra pound.
Good video. This is why I ended up buying a 30 lb tank of refrigerant and a weight scale so that I can put the correct amount in. I would love to have a charging station like you have but I'm just a DIY'er that fixes my vehicles and some of my friends and can't justify having one. I used to use the cans and a can tap and it was hard to put the correct amount in. I taught myself how to do AC repair work back in 2006 by reading AC repair books and by researching on the internet. Bought the correct gauges, vacuum pump, and other tools and have successfully fixed about 15 vehicles over the years. I also got my 609 cert so I could buy R12 which I still run in one of my older vehicles.
@@obsoleteprofessor2034 I bought a mostly full 50 lb tank of R12 probably about 10 years ago or so for about $250. I still use it in my 92 Chevy Cavalier.
Hmm that's interesting, I was expecting the high side pressure to increase more dramatically from such a significant overcharge. Thanks for taking the time to make these videos!
The symptoms you show can also be caused by defective engine cooling fan or dirty condenser fins. Best way to tell if a system is over or under charged is to check pressure without starting the engine with the engine temp at ambient. High and low pressure will be equal. Pressure in PSI should be very close to ambient temp in F. There are charts available in the shop manual for this test. Retired Ford Engineer with 51 years experience fixing Ford, Mazda, Volvo and JLR vehicles in 46 different countries.
@@brucewayne-ej3cx Keep the high side gauge valve closed anytime you are running the engine with the A/C on. The reason is if the A/C is on, the compressor would be pressurizing the Freon supply tank which can be very dangerous. The supply tank could explode.
@@parolajd I'm glad you told me this. Lol it's a bit late tho I did it the wrong way it worked out thank God. It did seem a little sketchy but it worked. Next time I'll do it right.
@ John Parola You should make a diy video for fords. I've always had fords along with their issues. And fix the majority of the problems myself if at all possible. This Ac compressor/ system diagnosis / fix is one I'll probably end up having a shop fix as I do not have all of the tools.
@@parolajdif the pressures aren’t equal at ambient temperature and cold engine at rest ,what this could mean Sir ( probably some obstruction, the temperature in the vents goes down to 34-36 F by the pyrometer ) ? The ambient temperature 80.7 degree F by the pyrometer and 81 F by regular wall thermometer. High side pressure is 100psi and low side pressure is 80 psi static on cold engine . All pressures are taken from the black scales in psi of the gauges. Even reversed the gauges to see if they measure properly and they are correct . The pressure- temperature chart for r134a says the pressure need to be 86.7psi at 80degrees F and 88.4 psi at 81 degrees F .
When properly charged, weak compressor will give them same symptoms. It's hard to suck than to push and you need a good pressure drop to boil off in the evaporator.
@GGALLIN1776 red angel AC stop leak 2oz bottle works incredibly well. IDK about the can with the hose, but I used the 2oz bottle in my daughter's mustang with a leaking evaporator and it worked wonderfully. Gotta know what you're doing though. Highly highly recommended.
@GGALLIN1776 actually any part that can be properly replaced I'd do that, but an evaporator where the whole car has to be torn apart, definitely use the stop leak.
My truck’s low side pressure is too high. Freon is good and no leaks but it is not cooling. The mechanic said there is restriction and that I need to change the compressor and accumulator. The compressor is working it is just not cooling. What is your opinion on that?
I have a 2011 F250 that I bought used in 2018. I never had any AC problems and I've never added any refrigerant. Recently it quit cooling. If I put it on max cool it will eventually come on after 10 or so miles of continuous driving. I thought maybe it needed charging so I bought a can of refrigerant and connected it to the low pressure side. I DIDN'T ADD ANY REFRIGERANT, but the gauge read nearly 90. The ambient temperature was about 78 degrees F.
Is there any concern with potential oil added with those DIY cans? We did a can, pulled .9 oz oil, but didn’t bother adding any PAG after the recharge...the can only indicates 5-15% PGME of a 20oz can...compressor ok with the added oil? I just love the ‘propriety’ mix along with the concentrations are ‘trade secret’ according to their MSDS.
But more is better! Good demo. Whenever I see those MONSTER 20oz or more "AC pro" cans in the parts stores I wonder how many people have dumped those into good systems. Heck, newer vehicles are full at 16oz sometimes.
@Mustang Ricer6589 Not out of reach in some places, they have the small cans ready for sale at places around me. Still $$$ but it will come down in price.
Or they buy it because it says, With Stop Leak. I’ve been doing this for 40 years, there’s no such thing as a stop leak for A/C systems, only destruction.
I have 2013 f150 that was blowing cool but thought it could be colder so I used one of those cans. Now when I turn on my ac the fan goes to high speed. I'm guessing it is doing this because it is over charged? Would it be best to drain it all and just have it recharged?
I had a garage service my working air con come back not working they said my compressor is bad. It would turn on for a second make a very bad noise turn off. I hooked up my own air con gauge. The low side was on 100 psi WTF they overfilled it. We got it back down to 35psi. Works perfect now no noise ice cold. Dont know if any long term damage but right now its good. Makes it worse my work boss owns the garage lmao. I told him your guys nearly destroyed my air con. They are in the shit. lucky for them it was my car not another customer. Would have cost him.
Thanks for the video! I was wondering... as for a DIYer, if lets say I overcharged my system and I got only this cheap low side pressure gauge, would that work if I just drop the pressure back into the 12oz AC can with my car shut off when system has equalized pressure of 80-90psi...? So that it doesn't get vented to atmosphere.
@@ve2430an empty can has zero pressure. An equalized system is going to have positive pressure. Simply connecting manifold to can will pressurize the can with refrigerant. At least until the can equalizes to the system. Then use another empty can.
Converting the low side pressure to evaporator temperature is a great tool to help visualize why the air coming out of the vents is warmer. Initially your evaporator temp was 44 degrees. Afterwards it was 58 degrees. Obviously the 58 degree coil won't cool as well. BUT, don't confuse that with undercharging a system, i.e low suction pressure. As he points out tho', more doesn't mean better. Great video.
You should make a video showing how to tune the system for optimal cooling, in the dead of heat. I find that recharging to spec, and removing tenths at a time, yields some pretty impressive results. It's not a free lunch however, you sacrifice optimal output at lower temps, and make compressor cycling duty load higher. I've used other gasses other than r134a in my personal systems, and have achieved great results for super cheap.
I've always wondered if there was someone else out there that does that!! I do the same thing. I've never recharged and stopped at spec. I've always gotten really cold air conditioners from just playing with the freon level. Mine have always been coldest with less freon than spec. Is that what you've seen over the years?
@@TheVenom8343 and under charge can make it cooler. I know that in residential systems the evap coil will freeze over if the system is under charged and air will stop passing through the coil. Another issue with low charge is that you will increase compressor cycling which may decrease your fuel economy on the car and increase compressor wear.
@@pibblesnbits Yeah, it freezes up. But I throw it over to "vent" and she's thawed in 30 seconds or so. I choose to do that because my A/C will blow 28 degrees F and boy that's nice down here in hot ass MS!! Lol
I'm in MS as well. My 2014 will only blow 60 degrees out the vents. I changed the expansion valve today and same thing. What kind of freon are you using? I put 2 12 oz can which is 24 oz which is what the sticker says. My gauges read 25-30 and 15-200. So I added a extra can. Pressure went up 30/200. Temp gauge dropped to 58 or so degrees. What are your Pressure readings?what part of MS are you in?
Question? Why would I have ice cold AC at idle but when on the highway it warms up and not as cold? At idle I am showing 38-40 degrees and on highway showing 55-60? Any help is greatly appreciated. Thank you
@@ed4709 If its goes back to blowing cold again when you come to a stop, (Without needing to bump the a/c clutch) its likely an undercharged a/c system.
The other issue people don't understand well is how dramatically ambient temperature will change absolute gas pressures. Never interpret pressure readings without adjusting for ambient temp.
I was just checking my 93 F150s air and when I looked up the pressure chart online it stated for 90 degrees the low side should be between 45-55 psi and for 95 degrees it should be between 50-55 psi. I set mine at around 45 and it was blowing colder than at 35psi, what gives?
Too low of a charge and the lack of refrigerant will not let it absorb as much heat to cool the air in the car like it should. It’s all about the refrigerant sucking up heat and turning from a liquid into a gas in the evaporator. Too little and it turns to a gas too soon to really cool the interior off.
I LOVE THE VIDEOS, FRIEND, THANKS FOR YOUR KNOWLEDGE. YOU ARE THE BEST !!!! (Sorry, I don't speak English.) ME ENCANTAN TUS VIDEOS AMIGO, GRACIAS POR TUS CONOCIMIENTOS. ERES EL MEJOR!!!!
Just replaced my entire A/C system in my 2011 Crown Vic. Charged it up to the exact spec of 27oz with an A/C machine. Pressures indicated an overcharge. Evac and recharged it with about 3oz less that the spec. Works great now! I did use aftermarket components, my theory is the aftermarket condenser has less capacity than the original. Anybody ever run across something like this??
According to the R-134A T/P chart, at 90° ambient, the low side should be between 45-55psi and the high side between 250-270psi. If your system was indeed at the right capacity at first, then hooking up gauges and going off the R-134a T/P charts will tell you nothing about the system state of charge, as it was telling me it was low at first and good after you added 1lb.
Hey guys I have an 03 Expedition I just put a new compressor dryer and front and rear expansion valves in it my high side pressure is 225 my low side pressure is 60 I live in Southern Florida it's been in the high 90s. And my AC is not blowing cold at idle I bring the RPMs up it gets cold off I'm driving it gets cold when I bring the idle up high side pressure goes to 300 low side goes to 35 or 40 anybody have any ideas?
My brother has a 2010 Ford F150 Lariat with inadequate cooling. After correct charge is added to vacuumed system high side pressure rises to approximate normal while low side drops to near 20 PSIG and the low pressure control cuts out the compressor clutch - the compressor only stays engaged for less than 30 seconds each cycle and then cuts off, comes back on after low side pressure rises to above 40 PSIG . This repeats endlessly. The expansion valve, refrigerant lines and condenser coil have all been replaced (individually) and the symptoms have not changed. Overcharging intentionally causes the high side pressure to rise but has no effect upon the low side pressure. Any suggestions?
Hello, when my 78 FORD GRANADA Was new it was December, first spring turned it on Scared me the belt was howling, as the compressor tried to run, went home took a look, OK OVERCHARGED Got an EMPTH throwaway cylinder put it in a vacuum, tossed it in the FREEZER, removed the charge & WEIGHED IT. 7LBS ,,,,,WOW NEW CAR pulled vacuum on car , weighed in the charge , never had a problem with it after , just goes to show you , NOT BECAUSE ITS NRW, DOES NOT MEAN ITS OK., that was R12 CHEERS 🇺🇸🇺🇸🇺🇸🇺🇸
I've wanted to ask you a question about cooling. I've thought about installing a good aftermarket or something from the junkyard. A stand alone electric fan over the hottest spot on the radiator that is run / turned on by a switch in the cab. Say on a really hot day or heavy stop and go traffic I can reach over and turn on that fan to increase cooling. Would that fan block enough regular cooling with the fan off that it does the opposite of it's intended purpose?
It disgusts me that we professional techs have to be certified to buy refrigerant and work on A/C systems but DIYers can buy the crap at the parts stores that contains sealant and might not even be real refrigerant. Some of it may contain propane, butane or a mixture of R134 and R12. I've not only invested a ton of money into my A/C machine, but had to buy a sealant detector kit and now need a refrigerant identifier so I don't wreck my equipment!
Question??? I have a 2010 F150 5.4L & the cooling fan is running & sounding at high speed all the time. Someone mentioned to me it could be a/c pressure switch problem. Problem is, I can't find it. Any advice on where it is located? Thanks.
I hear that new r1234yf is about $100.00/lb and it's flammable! Wth EPA! I also heard the A/C machines can detect a system leak and will NOT dispense refrigerant. $$$ :-0 Makes sense if this is true however.
It is flammable and at current pricing it's about $60.00 a pound wholesale to a shop. The machines you use will pull a vacuum and any leakage will prevent it from charging. However you can buy 8 and 16 oz cans online and DIY it and have the same situations that existed with R-12, R134A . All of those are illegal for a shop to knowingly "top up" without testing for leaks and repairing them before recharge. BUT DIY are exempt....
Blindly charging is the equivalent of using the "parts cannon" to fix a problem. If someone's going to attempt a DIY fix, get a gauge set and understand what the low side and high side pressures should be for the system and what it means when either or both are off-target. And if the gauges show the system is completely dead... don't just charge it! Vac it down, check if it holds vacuum... if it doesn't, charging the system without first finding the leak is a complete waste of money.
@@FordTechMakuloco Yep , agree 100% . I do check condensor fan running on low speed and I place a large box fan in front of radiator so mimics maybe 15 mph driving so condensor fan can have some incoming air pressure . Had to buy really good gauges since the budget gauges were not accurate . Done Subaru to Nissan to Ferrari AC rebuilds so learned to buy new compressors . Rebuilt ones don't last. And new TXV , o-rings and where applicable filter dryer.
I replaced the high side line where the pressure switch is and new pressure switch also. Filled it to 2 lb 6 Oz as listed and for about 2 weeks ran perfect. Clutch started to not engage so I figured was a schrader leak I was already aware of topped her off a little and went on about the day this happened one more time. And now about a month later the compressor clutch engages on and off at random times leaving the air hot or muggy and hot then hot. Hooked up my manifold gauges to it and the high side was 350! The low side was about 45. It was 90 out. What would any input be why it's doing this should I go get it evacd and recharged or is they another issue causing this aside being overcharged. I'm no mechanic so any input is appreciated just tryna save some money on my 07 mercury
Quick question, at Idle 86F deg. day, The pressures are ~30 / ~200. Windows closed, on recirc. Blower on high. When I increase RPM to 1500 - 2000 it seems to cycle often, every 20 - 30 sec. Seems the same with windows open. Is this normal? Thank you for your professional advice and videos.
Doesn't help when the restriction is what's in the pipes. I think with air it's for each psi volumes becomes half and then if you have drop or bends those will restrict
I was able to change both high/low standard schrader valve cores that were leaking w/o losing additional refrigerant on my 90s Honda. Thank you Mastercool!
@@jasonmorris2813 The tool has a built in ball valve controlled by a lever preventing the discharge of refrigerant and another part of the tool unscrews and removes the valve core aided by pressure from the system. It's a clever device using a simple procedure for removal and replacement. Sometimes they don't always work on the first try. They also make them for home A/C condenser units. Same process.
What if just the high side keeps going up? Ambiet is 75f, i was at 30psi low and high was 150psi with a slightly whiney compressor. Vents were still cold but i was worried about the compressor sound and decided to top off. I added about 2/3rds of a pound and the low side barely moved to 33psi but high side went to 175psi. Kind of high for 75f ambient no? Compressor is quiet now. Vents cool nice at 40f in the middle vent. Think I'm ok?
I have a 2006 sienna I change the condenser expansion valves and the AC compressor and only works basically in high RPMs when driving when the car is stopped, the AC is not cooling correctly. I change the gas today and the temperature before that was 250 and over.
This is not relevant to this video but maybe someone could help me out with this mess!!!! I just bought this little 2000 ford ranger it’s a clean little truck with a new engine in it but the guy has the a/c system hot wired. He has wire ran directly from the a/c compressor to the battery. If you touch them together the a/c comes on and it cools perfectly but I know this will eventually ruin the compressor. The problem is I don’t know where the original a/c compressor wire is. Any help would be greatly appreciate! Btw I love your videos ykys about ford vehicles,,,,, thanks for reading
Took my car to the dealership to have my ac serviced. Bought an AC pro refrigerant gauge to see what the low side was. It’s reading 110 psi. I’d assume the dealership has pretty severely overcharged the system
Those auto parts quick charge don't come with fancy machine like you got, you got to depend on the analogue gauge, I guess was not paying attention to quantity , just opened it all the way, so my Honda Civic was not getting cold like to should, After watching this video, I am pretty sure I overcharged it, So i had to let some out at low side at the schrader valve , I would let some out and keep checking, saw my temp gauge starting to come down, got it down to 40 , Worked like a charm, I was going to take my civic to a shop, Glad I saw your video, Thank you Mr Brian
The AC system on my Explorer has the symptoms of blockage when running. When I shut it off there is a 10 psi. difference between the low side and high side pressures which takes hours to equalize. Does this confirm the system has blockage? Thanks
If you have an ac system showing both low pressures on high and low and the duct temp warm, how do you know if there is a leak, a stuck closed expansion valve, orfice tube plugged, pressure or control valve failure, or just low refrigerant?
great video on the subject. question about testing the system, so once the car is nice and warm and ac system cycled for about 10 minutes, then you hook up the gauges. Now, with the vehicle running to get an accurate reading, do you let it sit at normal idle or do you bring it up to 1500-2000 rpm? I'm trying to diagnose the system on a 99 bmw z3 with seiko seiki compressor and not sure if this is rotor vane or variable displacement type compressor.
Thank you a lot for this video! Finally got my ac system working right and barely overcharged it. Your video helped me fix it amongst forums & ac psi specs that were confusing Thanks to the experienced commenters too!
After watching your other videos, I went with the little otc bottle and added it until the compressor stopped short cycling. I ran it for about 15 minutes and my windows started picking up condensation outside. I know I have a slow leak somewhere but with 200k on the beast, I don't think it will be around too much longer
What gets overcharged are consumers who bring their vehicles in to have their AC serviced by shops. That's why there's so many do it yourselfers out there. Servicing an AC system properly is a simple procedure if you know what you're doing and yet most shops charge an outrageous fee to do it.
Is the AC clutch engaging and disengaging? Because when you go into shops they say if that's happening it's either under charged or overcharged. Looking forward to your thoughts thanks
Thank you so much, very helpful information. I had over charged my ac after changing out an AC Condenser and it wasn't getting cold. The compressor kept turning on and off, I adjusted the amount of freon and its working fine now.
Great video and explanation! Ac work can be very simple once you understand how the system works but still can be confusing in certain instances. Thanks for the quick tip! Especially on a Ford! Lol
Quick question. I took my car in to a shop to get a recharge, I watched the guy do it as he connected the hoses and pressed buttons on his machine, but he never turned on my car. Did he do it wrong???
@@inverseuniverse5727 Absolutely wrong, no way of knowing previous charge and no way of having accurate high side reading without engine in operation.. You need at least 1500rpm to cycle the a/c and you need airflow over the condenser..
Not necessarily, if he pressed a button to “recover” all your Freon and then he pressed another button to “charge“ your ac with the manufacture’s recommended Freon weight, then you are correctly charged to spec. But, without starting the engine and engaging the compress, you would not know if the ac system had other issues.
My 2014 f150 says 24 oz. I put 2 12 oz cans in it and my pressure readings are 25-28 low side and around 150 high side. I changed expansion valve. Yours shows 34 oz. On your sticker. So I put 3 12 oz cans in it total because its 99 degrees here and 116 with the humidity. It will not blow colder than 60 degrees out of the vents. No matter if I put 24 oz or 36 oz. I'm just lost. My high pressure fans have kicked on but my pressure is around 200 and my low pressure is around 30. Do I still need to add more? I started to change the condenser with the expansion valve.
You have to look at the label for the AC system in the engine bay. Or Google ac specs for your vehicle. Do not go to a site where people are guessing what's you should do. Or take it to a shop.
At 105 degrees ambient I’m getting about 38/280 psi. Cooling is not great. What would you recommend? Are my pressures too low given the ambient temperature? All the charts I see state low side should be 50-55 and high should be 330-335 at 105 degrees
I have a 2014 silverado and the ac compressor runs but doesn't seem to pump the freon around. Pressure on the low side is greater than high side which is odd. And... the cooling fans does not turn on when I turn the ac on inside the cabin. Fans work fine to cool the engine but not turning on for the ac. I unpluged the Pressure sensor and fans kick high speed. Any thoughts?
If the pressure on the low side is high. The high side pressure cutoff is kicking out the clutch. Plus your AC cooling fan motor is dead. When you push the AC button on. The AC fan should be running.
May I ask you if you would have any idea what can I do to fix my problem. My driver side vents blow hot air. However the passenger side is blowing cold air out of the vents
Do you have duel climate control (separate air temp settings for driver/passenger) if so, sounds like the driver air mix motor is stuck on hot. Find where the air mix motor is. Then turn temp to hot and cold. It should move. If it does not move. Probably that motor is out. You can find the air mix motor on the passenger side and do the same. And you will see the motor move from hot to cold for a reference.
This is going to sound weird, but undercharging is a possibility. When undercharged, the evaporator can be cold at the bottom, but warm at the top. If the ductwork for the driver side is taken from the top of the evaporator, it will be warm air, while the pass side is cold. 90's Contours were like that. In fact, Ford had a TSB on that. (I was a Ford dealer tech thru the 90's)
According to the R134a charts for a 90 degree day, you were low to start with? But after putting more in it got too hot, so you were right. Are the Charts wrong??
Very useful demo video. Thanks a lot. I have a question though. You said that the pressure in the low-pressure section is a very important readings. It makes perfect sense as most of DIYers (myself included) have only the gauge for low-pressure measurements. You also showed the "normal readings" for "this weather". So my question is what is the normal pressure in the suction area? I can see in my car this reading can flactuate from 35 to 45 PSI just because of the ambient temperature. What should I consider as normal? Thanks again.
