What is the best way to charge the AC on a 2007 Prius? And how do I tell if it needs it in the first place? The AC blows cool air intermittently, the blower never stops. It's just intermittent cool air
Recharging an AC system is almost NEVER a solution to a problem. If it is low, the leak needs to be found and fixed. This has probably been discussed on here already. A search for "refrigerant" might help.
It's very easy. Toyota made the gen 2 Prius DIY friendly IRT charging the AC system. I've included the AC portion of the repair manual below as an attachment. I recently recharged a Gen 2 model. Not all leaks are worth investing a ton of money or time in repairing. A small leak that allows the system to run for a season is not worth investing a couple K $ for repair when $6 a year for a 12 ounce can of R134a works. Bigger leaks are obviously up to the owner. Your car has a sight glass near the high pressure test fitting. Clean it and look through it with the AC running on full blast and all doors open or all windows open. If you can see fluid moving (very low charge) or bubbles going by (slightly low charge) then you can add R134a (pure, no additives or oil) at the low pressure port. Just add small amounts at a time and watch the sight glass. Total charge from empty to full is 450g plus or minus 30g. That's about 15.9 ounces plus or minus 1.1 ounces. So if your system is essentially empty, but not full of air, one 16 ounce can of pure R134a would be about perfect. If you have air, it needs to be evacuated. The one I charged was low enough the compressor wouldn't even start. I plugged the test hose to the port just to see if it had any pressure at all. It did, so I was confident it wasn't full of air. I had a can already on my hose that had been used previously, so I didn't know exactly how much remained in the can. I added for just a few seconds and the compressor started running when I tuned on the AC and I could see refrigerant hitting the sight glass. At that point, I continued adding a bit at a time by cracking open the valve for a few seconds at a time while watching the sight glass and waiting for about a minute between adds. That can was empty after several minutes. Connected a new 12 ounce can and continued with same procedure. It went from refrigerant looking like a small stream hitting the sight glass to looking like an airy river shooting past then little by little the bubbles cleared up and the flow became smoother until there was just one bubble about 1/8th inch diameter right in the middle of the glass. Another small add and that bubble slowly became smaller and disappeared. At that point, when all bubbles are gone, (approx 350g in the system) the repair manual says to add 100 more grams (about 3.5 ounces). If you have a small accurate scale, you can get pretty close. I wasn't worried about getting it perfect right now, just functional. I just want it charged enough past the bubble point so I can evaluate how fast it's leaking. I can check it every day now and see if bubbles have reappeared. If it's blowing cold, but no bubbles, then I think it's safe to say it's a slow leak. At that point maybe I'll add another 100g to it. I think if you understand AC a bit, go slow and pay attention, the procedure in the repair manual works very well. The portion you're interested in starts on Page 136 I think.
As @lech auto air conditionin has gone into great detail on here on many posts the Prius A/C is a variable pressure system so the proper way is to evacuate all the refrigerant and precisely measure the weight with an expensive machine and then add exact weight of refrigerant and oil the specs require and then fine tune the system by measuring temp, humidity and pressure 1) inside the system, 2) outside the car and 3) inside the cabin. I'd be interested in what he has to say about this method you use in your manual. He writes super long posts that have taught me so much that I was convinced professional servicing is the only way to ensure you don't accidentally shorten the lifespan of the system. I will message him and see if he can participate in this discussion.
Yes I’m well aware of the old manuals that are repeats from the 60s in the 70s. Toyota has a lot of miss information of repeats because it’s cheaper to repeat all the information then to research and rewrite the book. A lot of Toyotas OEM factory manuals are on absolute cluster F@&$K with their Miss information is wrong oil fill charges when you add up the refrigerant oil quantities in one piece of information on the same article it doesn’t match in the individual components really bad math. I’ve released one or two videos about Toyota screwup on the refrigerant charge information which is exactly listed in the article above that has just been given in there oil quantities for balancing out oil in the new compressors. In the new Prius Prime the information is even worse. “(absolutely nobody uses sight glass on variable displacement compressor!)” Except those who don’t know any better it’s not even A discussion worth debating it’s right up there with holding aspirin between her knees and she won’t get pregnant sacrificing chickens and goats and reading their innards to determine the outcome of the war in our all-time favorite drinking bleach to prevent Covid the wise words of our supreme leader ( President Trump ) lol lol It’s OK because if it is in writing in black and white it must be right Just like the old electricians manuals to test high voltage by quickly tapping your fingers across the high voltage wires and describing the amount of tingling or pain to come up with a close voltage approximation and this was a legitimate way that was literally talked out of electricians manuals old school. Don’t forget to go down to the auto parts store and get the can with the extra oil, leak sealer to dye the special super cool additive and any others bells and whistle‘s snake oil that will be great for the Prius to because it’s in black-and-white in the brochure of the manufacture therefore it Hass to be the truth
In other words an air conditioning specialist with the right equipment is likely to do a better job than following the "repair" manual?
Definitely it’s not the tools that make the technician it’s the knowledge it’s not the knowledge that’s written into a book it’s knowing which knowledge is right and what your knowledge is not so right
> Talk smack all you want. If you read the post, you may notice there is mention of concerns. I never said this was a cure all. It doesn't make sense to spend more money than a car is worth to diagnose, repair or most likely replace components in the AC system. The reality of the situation is that by having some understanding of AC systems, and following the Repair Manual Procedure, the AC is currently working just fine in my friends 16 year old Prius, with an investment of about $10 and less than an hour of my time from the car pulling in until the car leaving. If you read the post, you may notice there is mention of possible concerns. I never said this was a cure all. I stated: I think if you understand AC a bit, go slow and pay attention, the procedure in the repair manual works very well. Ride your high horse all you want. Reality is what it is. Toyota built the car. I have no problem using their procedure.
I live in the deep South, and some people consider A/C to be somewhat non-optional. However (comma!) Many "technicians" in the auto HVAC biz use the same business model that AAMCO uses for transmission repair. For those not familiar, AAMCO stands for: All Automatics Must Come Out. They sometimes seem to use a troubleshooting device similar to a Magic 8 ball where 15 faces of the polyhedral die are inscribed with "Replace Transmission." Of course....automotive HVAC technicians have to use a MUCH more sophisticated device, since they have to divide the 20 possible answers between the major components of your A/C system with a 'replace compressor' bias. So...I've been a technician all of my [sic] adult life, and whether you're talking about electronics, automobiles, plumbing, home electrical, etc. sometimes people who are experts in their chosen field.....aren't. Or? They really ARE, but they're much more interested in fixing the machine than they are in helping people. Why do they sell all of those cans of refrigerant at the auto parts stores? 2 reasons: 1.) Refrigerants do not always stay inside the A/C equipment. This is especially true in cars, and especially after a decade or so of being bounced around in traffic and maybe swapping paint with other cars. B.) It is possible to to have a Leak, Weep, Seep, Ooze, etc that's not economical to repair. Anyone who has spent more than a few days in this forum has seen posts about the infamous Timing Chain Cover Leak. The timing chain cover is real. The Leak is real(ish.) It's really NOT usually a "leak" but rather a weep or a seep. The repair is effective and permanent. However (COMMA!) Before I go ripping apart a fairly new Prius and writing a check for $1600 to replace a $5 gasket I'm going to a risk assessment and maybe evaluate whether or not the juice is worth the squeeze. A heart transplant is 100% effective in eliminating a mitral valve prolapse, BUT(!!) it's not really the repair I would choose for this condition. We use a lot of different refrigerants in submarines. Submarines, like spacecraft, have atmospheric monitoring equipment and since dot.gov (unlike AAMCO) does not have to operate at a profit they have VERY expensive atmospheric monitoring equipment largely unchanged since the 1970’s. We use magnetic sector mass spectrometry and IR spectrophotometry sensors, miles of itty-bitty pipes, etc. We measure and have ALARM values for: Carbon Dioxide Hydrogen Nitrogen Oxygen Water Vapor Acetone Aliphatic Hydrocarbons Aromatic Hydrocarbons Benzene Carbon Monoxide Methanol Methyl chloroform Refrigerant 114 Refrigerant 12 Refrigerant 134A Silicone Stibine Trichloroethylene Unlike most parts of dot.gov, the US Navy has to operate within a budget. I know. I said earlier that dot.gov doesn't have to operate at a profit, but SOME parts of dot.gov really DO have a finite budget, and let's just say that R/D money is a little different than operating expense. So.... Ships have, LITERALLY, remained welded to a pier because the squadron ran out of money before they ran out of year.....but that's NOT why we're interested in refringent leaks. They can be dangerous to people. They can wreck equipment. Refrigerants in warships are NON-OPTIONAL....even when operating IN (not ON) cold water! And not just to keep food refrigerated and BELIEVE ME not for comfort!! So....is is often possible to have a refrigerant leak in a vehicle (even a car) were "adding a little refrigerant" is a very wise thing to do. It is also possible that not immediately and aggressively addressing a leak, weep, seep, etc is a very UNWISE thing to do. Still reading? Wow! Having said ALL of that, what is a person to do if their A/C isn't cooling? Me? I would lean away from dealers and specialty shops for a 14-year-old car. They have their time and place but I once replaced a solenoid, fixing my AC in a truck after getting TWO >$1,000 repair estimates stating that my compressor was shot and needed to be replaced.....so not all technicians are as free with their time and knowledge as some of the ones who post here. Use time to save money if this seems prudent. Gather knowledge. Lots and lots of high mileage G2s out there... Lots and lots of stores sell cans of r-xxx ... Good Luck!
The best way for somebody to attack this problem using that manual would be amongst the hottest days of the year so the system is fully loaded and stays on constantly so you can slowly add refrigerant as was stated. Slowly and carefully giving several minutes in between each small addition of refrigerant for the system to stabilize. And of course the most non-scientific method and definitely not the most EPA approved method or friendly to our atmosphere. Without equipment would be to dump the entire load of refrigerant into our atmosphere so there is zero refrigerant in the system. This way if you’re starting from zero and you have a small food scale that chefs use that Measure accurately up to about a kilo. Are usually accurate within plus or -1 g Most auto parts stores cans of refrigerant are either 12 ounces or 14 ounces by weight of refrigerant. So by starting with an empty system and using your scale with can with a little hose and attachment onto it until you have weighed in the amount that equals what is printed on the label on the hood would get you very very close to perfect. Most important thing to avoid is staying away from continuously operating or accidentally continuously under charging the refrigerant level what causes a high superheat lack of cooling and oil return to the compressor that shorten its life and lead to eventual compressor failure the most expensive big ticket item next to replacing a evaporator. I guess that would make a good video to post using a kitchen scale small cans of refrigerant starting on an empty system , up to a perfectly charged AC system This would be the cheapest most accurate way I can think of a do it yourself person with no experience to try to follow and nearly get it right every time. But of course he would have to definitely make sure there’s no air in the system You are trying to charge. If possible a local garage can recover the refrigerant out of your vehicle for you in some very low labor rate low overhead areas of the country they might do it for free and you tell them just keep my refrigerant. So you could go back home and fill it yourself starting from zero or there might be a nominal fee for the shop to do the refrigerant recovery for you But I’ve seen too many sightglass methods used that led to needed compressor replacement as an aftermath.
There’s a car I was testing that only had 375 g out of 420 g but yet the site glass was perfectly clear. you still get some cooling but on very hot days the compressor is being forced to overwind by the computer to compensate for the lack of refrigerant grossly overheating the compressor and shortening it’s life On the opposite side of the coin the opposite things happen for a situation where you’re feeling it by the site glass because the computer takes over and depending on the ambient conditions you can have bubbles in your sight glass but be over charged with refrigerant In that circumstance when you go into a very hot climate approaching 100° plus you’re high side pressure it’s just borderline in around 400 psi under those circumstances extremely low rain the life expectancy of your compressor. At the same time drawing a multitude of power consumption over the normal draining your high-voltage battery very fast reducing your gas mileage rapidly aging your high voltage battery because it’s constantly cycling because it needs to be charged all the time and then depletes constantly all due to an over charge of refrigerant and the same thing goes for an under charge of refrigerant electric compressor has the wind up more to compensate for the lack of refrigerant drawing more amps constantly drawing down the high-voltage battery. High voltage batteries have a limited lifecycle of how many times they can cycle up and down because of the heat generated So both gas mileage suffers from an improper refrigerant charge on vehicles with electric compressors. It doesn’t matter if it’s under charged it will over RPM the compressor with more WATTS consumed to drive it. If it’s overcharged it will still run for that extremely high pressure and it takes more WATTS to drive it because it Hass to work harder against the higher pressure. Same end result. Above are links to a Prius being tested having the refrigerant recovered showing that the refrigerant was low on charge but the site glass was perfectly clear. After the refrigerant recovery showing the recharge procedure and the pressures on the gauges and with a full refrigerant charge the site glass was still perfectly clear And then the difference in pressures again that are much different after the vehicle has been running for 20 minutes does not operate the same as a vehicle that was just freshly charged and started up. The majority of compressor burnouts on braces I get from Small automotive shops who are supposedly professionals who use the small can top off method using sightglass. And usually after a few complaints and attempted recharges repeatedly when the customer gets aggravated and looks for somewhere else and I get a hold of the car. I always find the exact same problem every time when I recover the refrigerant. It is always overcharged by a few ounces or under charged by a few ounces with the same outcome. When it works and falls in the perfect range that’s great good luck that’s when the happy story happens. But it’s the catastrophic failures that you don’t hear about and when somebody does they don’t want nobody to find out that they were responsible for burning somebody’s thousand dollar plus compressor up. Perfectly OK for a DYI person on their own dime to experiment and learn if they want to on their own car. But it’s not OK when it’s open supposedly professional shop using small cans of refrigerant and doing nothing but guessing ( topping off) trying to get close enough to get some cold out of the dash to make the The customer happy with cold air blowing out of the dash that you can easily do been under charged or overcharged getting that money from the customer but at the same time like a ticking time bomb the one who recharge the system is responsible for the compressor burn out that happens later on. That part is not OK
I would start by having an AC shop with Prius experience evacuate and refill the system, using refrigerant with dye. Then see how long it lasts and/or where it is leaking out. My point being that the repair you need to really fix this might easily cost $2k to $3k, which is enough that you might not choose to do it. Conversely, if the recharge lasts a year you might buy the right tools to do it yourself for a couple of hundred and just put up with it until some other part of the car breaks that takes it out of service. When we bought our 2007 used it included an extensive warranty from the Toyota dealer (and a somewhat higher price than it would have been without it.) However this paid off for us because the AC had a leak, and it took many trips back to the dealer to finally get it resolved, ending (we hope, cross fingers) with them replacing the evaporator which lives in the middle of the dashboard. Before they changed that part everything else they tried only held up for a month or so. If we had been paying for each and every one of those repairs the cost would have been much more than the value of the car. I suspect that whoever sold it to them may have had the A/C recharged just before the sale, to cover up the fact that the system leaked like a sieve, and so their umpteen billion part inspection would come up clean even though the A/C was at death's door.
In my job, I always get called out to mechanical Repair shops to recharge or look for a leak on very expensive evaporator type cars like Mercedes Benz or jaguar or Prius were evaporator replacement is in the 2K+ to $3000 + range I would charge them up and tell them that evaporator is leaking and we would need to replace it. I would charge them up and tell themThey would say because the car several years old they’re just going to sell it. So off I go Next thing you know in about two months I’m getting a call from a used car dealers In my area to charge the AC on a car because the customer is coming out to look at it to buy. When I arrive these vehicles I keep getting look really familiar. Because of the type of manufacture dye that I use that is extremely bright and a little expensive so usually nobody else use it it’s easy for me to tell what cars I work on. And I often have my sticker under the hood with a work order number on it. I tell them in either evaporator . I tell them it’s a evaporator and they tell me to fill it up because it Hass to have cold air for the next customer who’s coming down to look at it. Next thing you know I’m getting a call from another shop somewhere telling me that one of their customers recently purchased a vehicle and air-conditioning is not working to come down and take a look at it. So I drive down to the shop to look at this customer’s new car and behold I really recognize this vehicle by now. For me this is a weekly or monthly ordeal for the last 30 years I go through So I walk up to the car place my hands on the hood and I put on my act like a religious healer and go hallelujah amen. When I look at the shop owner or one of the mechanics who is telling me the history on the car and I tell him it’s the evaporator is leaking you can now write me a check for $170 for my exorcism ceremony and I’ll be on my way for my diagnosis. They look at me and asked me how do I know. Then I’ll tell them that’s what I told the original owner of the car when it was at a mechanical shop about four months ago and then that’s what I told a used car dealer what was wrong with it two months ago and now here we are two months later and this is what I’m telling you it’s the evaporator !. I only know one honest truthful used car dealer who actually repairs cars and does not repair them the cheap way. Yeah actually goes out of his way to find every little problem with the car and fix everything correctly before selling it out of 32 years of used car dealerships I have never met a car dealer like this one car dealer or individual.
Lech, that was very informative. Thank you. Something I suspected but of course could never prove. In these situations I think the one recharge is most likely never logged so that it shows up in the CARFAX records, certainly all the diagnoses without repairs are not, so a potential buyer hasn't a clue that this is going on.
WOW you touched on a HOT topic when you mention CARFAX SCAM, joke, and mirrors That topic deserves a whole Nother thread and discussion. Yes somethings are reported but only for the network of shops that sign up. Dealerships and networks intentionally avoid this by paying under the table and having a network of repair shops that won’t report so they could hide to work and sell the car for more in the dealership without revealing that it was in possibly a good size accident. It’s a very easy system to Manipulate. Because I’ve been in this business my whole life and my family for four generations have owned body shops and mechanical warfare and I’ve worked and ran both when I go to a used car lot I pick cars to pieces in front of the salesman and even find stuff they didn’t even know existed on previous repairs. First I let the salesman put their foot in their mouth and bring out the car fax to show to a friend or family member who I am at a company to inspect the car right at the dealership. I will find that whole door pillars have been replaced rear quarter panels under body panels from rear inclusions where they have to replace the panels all the way back where the spare tire sit because it’s been crushed before and the Carfax shows up clean. I had one in particular one that came from the Louisiana area where it was submerged in a flood water damage you would never want to buy one of these cars because of future electrical problems with corrosion it did not show up on the Carfax. Working in automotive trade you see all these coverups and scam’s that were sold to people as good used cars that look perfect but we’re in major collision even complete totals with no salvage title even though they should have a salvage title because the car gets spot third-party private cash under hand into a body shop body shop owner repairs it sells it back on the open market with no paper trail of all the repairs that were done. This is a daily occurrence hundreds and even thousands times a day in every state in every city in every town the smallest little Hickville to the biggest metropolis city. For us in the mechanical “know” on this side of the business we trust Carfax as far as we trust Trump to donate money to tearing down the border wall.
This is why I tell people that buying from a private seller in the parking lot of your bank where there's lots of security camera around and you don't have to carry the cash or check very far is the way to go. Not only do you save one or two thousand dollars on price buying from a private seller, but you have a far better chance of avoiding all the corruption in the used car sales biz... But most everyone who here this from me are unwilling to think it's safer than buying from a "reputable" car sales biz.
