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Under vacuum, the seals or O-rings will move in one direction and under pressure they will move in the other direction. Add your initial charge or fully charge the system and use your electronic leak detector to find the source. All according the Ford service manual. If the leak cannot be detected with the air conditioning system switched off, start the engine and operate the system to build up system pressure. At first, everything was fine. How do you test the A/C system in your shop in December, in Michigan or anywhere else it's winter and cold? These defined readings will tell you, based on the charts, what is the likely concern. In modern systems using R134a refrigerant, the leaks can be difficult to pinpoint as the synthetic refrigerant oil does not appear as an oily residue at the leakage point. Figure 9 - While doing your testing on a cycling system you need to read the gauges just as the compressor shuts off. A good visual inspection can find many problems. By taking a little care with your air conditioner over the winter months, you 2021 Classic Auto Air Air Conditioning & Heating for 70s & Older Cars & Trucks - All rights reserved, Auto Air Conditioning Evacuation: Not Just Testing For Leaks. At one point in my career, I worked in a Toyota store, and most of the work I did was installing A/C systems in new cars. That's my suggestion. I know about vacuum testing the systems. When using ultraviolet light always wear suitable safety goggles that screen out ultraviolet light. From left to right, a leak detector, sealant detector, and identifier. What does low side mean? Agood visual inspection, are there any obvious leaks? Using service publications prepare the vehicle for testing. Check for bubbles which would indicate a leak. Areas to checka) All connections and pipesb) Compressor drive shaftc) Compressor service valves and sealing gasketsd) Condenser and evaporator matrix tube endse) Receiver/drier or accumulator/drier connectionsf) Pressure switchesg) Spring lock coupling connectionsh) Hoses. Re: How can I pressure test the A/C system? The way you test an A/C system in December is the same way you test the A/C system in every other month of the year: by the book. Therefore you must do all testing inside a heated building. The exception to that is a recovery mechanism that is only used to recover contaminated refrigerant. The technical storage or access is required to create user profiles to send advertising, or to track the user on a website or across several websites for similar marketing purposes. As a Ford trainer and a college teacher teaching A/C systems, how could I teach A/C diagnosis? Your system may not leak under a vacuum, but under pressure it may. Do I Need To Add Oil To My AC Compressor? Engine torque conditions are within normal parameters. A case in point is our in-dash air conditioning and heater We recently heard from a customer interested in having his original 71 Pontiac LeMans evaporator unit with POA valve rebuilt & restored and set up for 134a. The technical storage or access is necessary for the legitimate purpose of storing preferences that are not requested by the subscriber or user. Wires disconnected? Want to start the conversation? Our advice is to start by the O-rings as it is not unusual for one to have been crushed or split by over-tightening during installation.). As you probably know, when the ambient temperature is below 32 degrees the system won't turn on. How do you test the A/C system in any weather, anywhere? To repeat, we recommend 30-45 minutes of evacuation at 28 30 Hg of vacuum. Powered by UBB.threads PHP Forum Software 7.7.1. We'll get to it shortly. This question comes up because people want to avoid poor cooling or failure problems Corvette model years affected: 1968, 1969, 1970, 1971, 1972, 1973, 1974, Your wish is our command! The dye can be added to the refrigerant system during repair, or during the evacuation process, depending on the equipment available. Pressure equalization is what happens to the operating high and low side pressures (they equalize) when the system is shut off. . . Testing1) If the air conditioning system is still operational, recover the refrigerant. Not only could you damage the system you can severely injur yourself to include death. I have heard of 250 PSI damaging low side components (evaporator) but maybe it was already on its way out. Ill find a professional who can do it and get it done right the first time. NOTE: Leak testing dye may have already been added to the system by the vehicle manufacturer. Electronic controls and the possible concerns that may be caused by skewed sensors, faulty programming, and drivability issues are each worth their own articles. Wide Open Throttle (WOT) condition is not present. See our August 22, 2014 Tech Talk Post: My mechanic says I need to replace my AC filter drier. Ford introduced the Flex in the late Summer of 2008. Another vote for a vac test (although a system that will hold. The high or high pressure side is from the compressor to the expansion valve. Adding a small amount of refrigerant and using a electronic leak detector can also be done.-------------------------, Big Blu works great for finding leaks when system is under pressure. After about 10 minutes I noticed the air blowing out was getting colder and colder, and I heard the A/C clutch engage. It is showing that ambient temperature is ~70 degrees and the refrigerant pressure is `70psi. Look at this list of requirements for the PCM to engage the A/C compressor on a late model Ford Expedition: When an A/C request is received by the PCM, the A/C clutch relay is engaged when all of the following conditions are met: Excessively high or low refrigerant pressure from the A/C pressure transducer is not detected. IMPORTANT: DO NOT exceed the recommended pressures (use a pressure regulator) and DO NOT operate the air conditioning system with oxygen free nitrogen (OFN) in the refrigerant circuit. What is an electronic leak detector? Do you agree? (Direct Electric Replacement ) controls, we have received loads of requests Later in the month of April, I'm heading to New York City to see two icons brought together who haven't met in decades. You would be better off pressure testing the system as well as vacuum testing. 4. Good article, I am licensed, and journeyman level A/C refrigeration tech since 1983. Classic Auto Air has always taken pride in the fact we have an extensive quality control process. Another benefit of air removal when can charging is that it eases the initial charge of refrigerant into the system. Figure 6 - This gauge set has been connected to a system that has not in operation. His thinking: I checked for leaks, now Im moving on to the next step. He was not only evacuating and charging without a license but without any understanding of what he was doing. If you are able to, put a gauge on the low or high side port and then pressurize from the opposite port. Manufacturers have been given emission credits for using R-1234yf. Let's start by answering just the first question. This is done to provide dry air to help defog the windshield. Why 30-45 minutes? Let's review a good procedure for any time you test the A/C system, starting with the legal requirements. Vacuumed for a half hour then let it sit for another half, and it held (not sure if it was necessary to do that latter step since it didn't leak under pressure, but figured it wouldn't hurt). I would like to keep the system original. I fibbed earlier about using nitrogen. Added to that was a sunny day so between the sun load sensor and the ambient sensor the system "thought" it was hot outside and turned the A/C on to meet the request for an inside temperature of 70 degrees. In those days when I would be out shopping with my wife, I would sometimes wait in the car while she ran in to pick up whatever it was she was after. I never heard the 134a cancer link, but heck as long as it does not hurt the environment who cares how many PEOPLE it kills. If another shop installed one of those refrigerants it should be tagged under the hood and have fittings that are different than those for either R-12 or R-134a. As with any article or other automotive technical training, there is no perfect, works every time it's tried method of repairing cars. Chevy Corvette Perfect Fit Air Conditioning System Updated April 2014, Air Conditioning Upgrades for Mopar B Body Cars 1968 1970, Connecting a Serpentine Belt System to Factory Air in a 1970 Chevrolet C-10, Weird Winter Tip to Keep Your Cars A/C Compressor from Springing a Leak, Typical Problems Encountered In Charging The A/C Kit, 1970-72 Chevy El Camino Smart Series kit. Leak testing with an ultraviolet lampTo make leaking refrigerant visible under ultraviolet light, the refrigerant gas is mixed with a special dye which is added to the refrigerant. I noticed a thread on the site here which said argon was OK to use, so figured I'd be safe.Many thanks for all the help.Edited: Fri August 15, 2014 at 12:40 AM by seagull369, http://www.ackits.com/index.php?route=product/product&product_id=31708&search=big+blu. When a refrigerant leak is detected, the tester will emit an acoustic signal. During hands-on training, I would create bugged vehicles that the technician or student had to analyze for the likely/correct fault. Its worth it to get it done right. Why do you say intitial leak check? You will also want to have a refrigerant identifier, leak detector, and sealant detector that you use before connecting your gauges to the vehicle (Figures 1, 2). I used argon from my TIG setup instead. In my most recent review of Federal Section 609 requirements for motor vehicle HVAC technicians, the first requirement when performing A/C work for consideration is to be Section 609 Certified. Let me translate that for you to be very clear. I bought a cheap one from harbor freight that operates off of a shop air compressor. Again, your shop should have a procedure based on Federal and local regulations of what to do next. One time it was a day in December, the ambient temperature was about 32 degrees and with the inside temp set to 70. Engine coolant temperature conditions are within normal parameters. 196419651966196719681969 1970197119721973, 196619671968196919701971 197219731974197519761977 19781979, 195519561957195819591960 196119621963196419651966, 194819491950195119521953 195419551956195719581959 196019611962196319641965 196619681969197019711972 197319741975197619771978 1979, 196719681969197019711972 197319741975197619771978, 195819591960196119621963 196419651966196719681969 197019711972197319741975 1976, 195519561957195819591960 196119621963196419651966 19671968, 195819591960196119621963 19641965196619671968, 196219631964196519661967 196819691970197119721973 19741976, 194719481949195019511952 195319541955195619571958 195919601961196219631964 196519661967196819691970 197119721973197419751976 197719781979198019811982 19831984198519861987, 196919701971197219731974 197519761977197819791980 198119821983198419851986 198719881989, 197719781979198019811982 198319841985198619871988 1989, 197519761977197819791980 19811982198319841985, 196119621963196419651966 196719681968196919701971 1972197319741975, 196119621963196419651966 196719681968196919701971 1972197319741975, 195919601961196219631964 1965196619671968. Test for sealant in the refrigerant system. Independent Automotive Aftermarket Federation, VLS - Verification of Lubrication Specifications, Original Equipment Suppliers Aftermarket Association (OESAA). 3. Upgraded another of our model-specific complete Perfect Fit A/C Kits. I was recently talking with a sales rep from one of the large parts house chains, he was explaining that they sold a device that attached to your machine and would strain the sealant out during evacuation, protecting your machine from damage. Why 28-30Hg of vacuum? Watch the gauge for 20-30 minutes to see if you have a pressure decay. You may be able to check for leaks, but even in Death Valley youre not getting out much moisture. How could I know the techs/students had learned how to test the system and be confident that the techniques would work when called upon, when evaluating A/C in the winter? Factory original purists may balk, but sometimes original dashboard designs can be improved upon. Start the engine and operate the air conditioning system. That said, weve run into many experienced car guys who dont really understand evacuation and decided a quick summary would be helpful to even licensed AC professionals. Pass the probe under the suspected leak area starting at the highest point in the circuit (refrigerant gas is heavier than air). Go to a licensed professional. One of our favorite Go-to-a-licensed-professional-for-AC-system-charging stories involves a guy we spent more time than we care to admit troubleshooting before it became apparent that he was releasing the vacuum before charging. Let's get back to how to test the A/C system of that car sitting in your stall regardless of the month and ambient conditions: 1. The first TSB on that car was 08-20-5 about poor A/C performance in ambient temperatures above 100 degrees. The fact that it has ANY pressure in it at all tells you it's sound. As you work on vehicles (and I cannot emphasize enough), the importance of understanding how the system works, and using service publications to direct your steps as you analyze whether or not the system is working like it is designed, is extremely high. Plus, there are other steps that you will want to do before you even think about connecting your gauge set or recycle machine up to the vehicle. One of the primary sensors for the control of the system was the ambient temperature sensor, in front of the condenser, behind the grille. One of the first cars I owned with automatic temperature control was a Pontiac Bonneville SSE. If you evacuate for 30-45 minutes, the filter-drier should handle any residual moisture without a problem. Without a subpoena, voluntary compliance on the part of your Internet Service Provider, or additional records from a third party, information stored or retrieved for this purpose alone cannot usually be used to identify you. On this vehicle there is communication across three networks and between four ECUs, just to turn the compressor on! You such all the air out and make sure it holds the vacuum. Can you open the can, replace the filter and dessicant and weld it up again. Follow the OEs service procedure, be ready to fix seemingly unrelated concerns, and for refrigerant concerns, rely on the performance test. This site requires you to register or login to post a comment. I'll report back to let you know how it goes.. Since refrigerant is heavier than air, spend additional time on the under-side of components. If something is not right (airflow across a heat exchanger, the flow of refrigerant in the system, and passing the restriction, or lack of one), all of these concerns create an effect on pressure readings. Following the manufacturers instructions add the amount of dye stated to the refrigerant system. Note these readings on the repair order and then compare to the analysis charts in the service manual. By comparing this to your chart for R-134a this is a good indication that what is in the system is R-134a and there is enough refrigerant in the system to begin testing. A frantic call to the service department and the first available appointment later and I was doing A/C work. The pressure should equalize on both sides if only applied to one side, if not, you have a blockage. I'll explain why that is critical in just a moment. Classic Auto Air has been using the latest technology to create high performance model specific A/C kits for your 1940s-1980s vehicles since 1977. Swab the suspected area with the solution. Don't actually own a tank of that (yet, anyways). Ill keep in mind what you said about AC professionals and that you shouldnt try to charge your cars AC without their help. When he charged an air-filled system, he created pressures that were way too high. Do you agree? Instead they are evacuated using a vacuum pump. In the recent past I spent several years working on the repair of HVAC systems on new units at the factory. What we go for are procedures that work as close to nearly all the time they are used, as possible. POA - an abbreviation for Pilot Operated Absolute - valves are Well, we've done it again! I mentioned that sensors that can cause problems. summer will be here before you know it. Only had to pressurize to about 70psi before it started hissing. The technical storage or access that is used exclusively for anonymous statistical purposes. 11. This TSB directed the techs to evacuate the system and recharge with a specific amount of refrigerant. 8. It was reading under hood temperature. If the system charge is too low, the refrigerant will need to be recovered. All rights reserved. 2. If you have a sniffer, first put an oz or two of refrigerant in the system and then use the N2. Leak testing using an electronic testerElectronic leak detectors can be particularly useful in finding very small leaks. The EPA is requesting that techs re-certify for R-1234yf but are not requiring it at this point. NOTE: If the system is empty, DO NOT charge it with refrigerant, carry out leak testing with oxygen free nitrogen (OFN). Look up the test procedure in service publications. The EPA also has stiff fines, and penalties for people who illegally work on A/C, and refrigeration systems weather you are a technician or not. The EPA has indeed identified certain refrigerants that you may use in place of R-12 or R-134a, these are SNAP refrigerants, Significant New Alternative Policy. (You need to get at least 50psi of refrigerant into the system before you turn the car on. The answer? I digress, back to Step 8; the performance test is designed to find refrigeration system concerns and is based on the reality that for any given temperature and humidity level a properly charged, correctly operating system will have defined pressure readings. Any new components installed? Those sniffers are very senitive and the tip can be ruined/tainted real easy. The next step is to set engine speed to spec and monitor outlet temperatures and note pressures to compare to the chart to determine if the system is working as designed. (Figures 3a, 3b). If you continue to use this site we will assume that you are happy with it. Today, most automatic systems have a strategy built in to ignore the ambient sensor when the vehicle is standing still. If you have gotten past the first three, is to connect your gauges-machine and note static pressures. Dry nitrogen is the way to test with a true pressure of what the system would run. Evaluating the performance of an air conditioning system is not a difficult task, especially when in the hotter climates. Hose was replaced, system was pressured again to about 100psi (I was chicken to go any higher). Aluminum components and seals are particularly vulnerable. After 30-45 minutes of evacuation, close the service valves and turn off the pump. No, I'm not talking about seeing Rocky meet up with Apollo Can aftermarket air conditioning components improve on OEM design? Ignorant people do stupid things, check your technicians certifications before trusting your system to possible damage. Evacuation Purpose #3: Removing Moisture Moisture removal is arguably the most important purpose of evacuation as moisture is the leading cause of AC system failure. Because despite what our customer thought, minimal initial vacuum loss is not a guarantee that your AC system is leak free. At one point in time, many manufacturers recommended that if you found sealant in the system that you button it up and give it back to the owner. . Let me explain that with an actual example. You should always run an electronic leak detector over the AC system after you charge it. The original filter/dryers are no longer available. By now I am sure that most of you have figured out the answer to the question of testing in cold weather. I don't have an A/C machine at home but I do have a set of gauges. Moisture wont be drawn out by the vacuum pump unless it boils. 10 to 15 bar (sufficient for leak testing purposes), and close the valve. Figure 1 - This type of machine is required by the EPA for each type of refrigerant that you service in your shop. As long as you have been 609 certified you may legally work on R-12, R-134a, EPA SNAP refrigerants and R-1234yf for consideration. Ive done AC since the 80s.You pull a vacuum and let it set.See if it drops.Then you add a small charge and use either a black light or leak detector.I prefer the light as the dye is easy to see.If you have a leak you usually reclaim the 134 you put in.We did have a 12 machine at work but it hadnt been used in 5 years.I might have a heater core.I cant remember if I scraped the heater setups from my 70 Imps.Rocky. I always like to baseline my training so everyone is on the same foundation. I would simulate airflow issues by placing obstructions in between the condenser and radiator, faults in cooling fans, even faults in engine sensors for them to find. We use cookies to ensure that we give you the best experience on our website. The gods here say not to go over 150psi. If there is vacuum loss of 2 or greater, there is probably a leak. Figure 5 - There are choices for identifiers, this one is showing that the system has 100% R-134a in it. Our customer didnt get this. https://www.facebook.com/AutoBodyRepairNetwork/, https://www.instagram.com/ptenmagazine/?hl=en, https://www.linkedin.com/company/40735491/, https://www.youtube.com/channel/UCxBEkpoYgmG0r34_B3mOr4Q. It also required a recalibration of the PCM. The initial starting point for this test was the band at 2.4 on the scale. To summarize proper AC system evacuation: -Dont do it if you are not a licensed professional -New filter drier -Evacuate for 30-45 minutes at 28-30 Hg -Let the AC system sit for 10 minutes. Its typically quite obvious to both consumer and technician, when the A/C isnt performing properly. If found, follow the procedure that your shop has for systems that are contaminated with sealant (Figure 4). If you are not EPA certified 608 and 609 at a minimum you should not attemp to service the system. Figure 2 - Examples of tools needed to test the AC system. 5. Check for TSBs and other possible pattern failures during this check. In this article I have focused on just testing the refrigeration part of the AC system. 4) Using a commercially available bubble dye solution, spray the suspect areas to locate the leak. Go to a licensed professional. Using an injector, dye can also be added to the low pressure (suction) side when the system is being charged. For approximately the last 30 years, the A/C systems (both manual and automatic systems) have an HVAC module in communication with the Powertrain Control Module to control compressor and cooling fan operation. What was going on? 2) Connect the cylinder of OFN to a service connector, component or line, using a suitable adapter. No comments have been added yet. http://www.ackits.com/index.php?route=product/product&product_id=31708&search=big+blu-------------------------, I found the leak in a hose leading to (or away from) the compressor. The real question is: "How do you test an A/C system?" AC system evacuation serves three purposes: 1. Diagnostic strategies for problem vehicles, Living in a vacuum: Crankcase ventilation system testing, COP Ignitions What goes wrong, and how to test them. 2022 Endeavor Business Media, LLC. This can and does happen. Compressor, lines, receiver-dryer or accumulator, heat exchangers. Let the system sit for 10 minutes. Give me a minute to finish the process and I'll explain the differences for cold-weather testing. I didn't know about the pressure equalization thing. The ambient temp sensor was close to the radiator and not in a position to have outside air blowing over it while parked. CAUTION: Excessive ultraviolet light can damage eyesight.