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A/C Compressor

  • If the compressor is engaging, the center of the compressor clutch will turn with the outer pulley. If the pulley does not turn and there is a loud squeal, this usually indicates a locked up compressor. The compressor and drier will need to be replaced.

  • If the vehicle’s refrigerant is low, the low pressure cut-out or low pressure cycling switch can prevent the clutch from engaging. Adding refrigerant should alleviate the problem.

  • You can tell if you compressor is cycling on and off by looking at the clutch (or belt pulley) at the front of the compressor. The center of this clutch should be spinning when the compressor cycles on. Please note that the pulley itself will always spin while the center of the clutch may not.

  • When you overcharge your vehicle’s A/C system, a pressure cut-off switch is activated to stop the A/C compressor from running. In turn, this will cause the system to blow warm air. If this happens, you will need to bring your vehicle to a certified A/C professional or technician to have the excess refrigerant recovered (i.e., removed) from the system. Remember that it is illegal to vent refrigerant from your system into the atmosphere, and the government can impose stiff fines for failure to follow this law.

  • In order to prepare a new compressor for installation, it will need to be primed. Not doing so may cause serious damage and void the compressor’s warranty. Priming a compressor involves adding oil to both the receiver-dryer and suction port of the compressor to lubricate it for use. Prior to starting the process, it is vital to know the oil capacity for both the system and the compressor prior to starting. This information can be found on our Spec Database.

    Once you have determined the proper amount of lubricant your compressor needs, pour half of the specified into the suction port of the compressor and the other half into the receiver-dryer. After the compressor is installed into the vehicle, you will need to rotate the compressor clutch 10 to 20 times to ensure that the oil is properly distributed throughout the system and the compressor. Tools will be required for this. Be careful to not turn the compressor nut in the middle of the pulley as it may affect the air clearance between the clutch pulley and the clutch faceplate. After you have rotated the pulley 10 to 20 complete revolutions, the priming procedure will be complete and the compressor will be properly primed.

  • Yes, but only specific products. Be sure to check the label on each individual A/C Pro® item to assure best use practices.

  • Unfortunately, the caps on the high and low pressure automotive air conditioning service ports vary. In most cases, both caps will be black, but we have also seen them in grey, blue, and green. Sometimes they have an “H” or “L” to indicate High or Low pressure ports.

A/C Basics

  • To find where the low-side service port is located on your vehicle’s air conditioning system, look for the valve that is located on the line that runs from the compressor through the evaporator and up to the condenser on the low-pressure (suction) side of the system. These ports are sometimes covered with a cap marked “L” for “Low.” Note that R-134a recharge hoses have couplers that will only fit on the low-side service port of R-134a systems, and the same goes for both R-12 and R-1234yf. If you don’t know where your low-side service port is you can locate it using our Port Locator tool.

  • The EPA requires that ANY replacement refrigerant MUST have unique fittings, charging devices and label. Therefore, the EPA states that “drop in” refrigerants are illegal. Furthermore, only R-134a has been tested and approved by the original equipment manufacturers.

  • No. Federal law prohibits topping off an R-12 system with something other than R-12 refrigerant. Your options are to locate some R-12 refrigerant if you are certified to purchase, then add it with an R-12 recharge hose. Or you can convert the system using one of our R-134a retrofit kits that will allow you to now add 134a refrigerant to your automotive air conditioning system. You will have to make sure that you remove any residual R-12 refrigerant by having it evacuated prior to retrofitting your vehicle.

  • The answer here is two-fold. It’s possible that the system has a small leak and is now low on refrigerant, which will allow the system to blow cold but now as cold as it used to. In this case, start by checking the system pressure via the low-side port. If it’s low, add refrigerant or a refrigerant with a stop leak to correct the system pressure. If the pressure is correct, adding additional refrigerant will not make the system blow out colder and will in fact cause the system to be overcharged. This will result in the system working less efficiently and warmer air will blow from the vents.

  • All A/C Pro® products contain the proper ratio of replacement oil.

  • A pressure gauge must be used to determine the accurate system pressure and thus amount of fill. All A/C Pro® gauges indicate whether you should continue filling (charging) or not.

  • If you are replacing a component part in the system or if the pressure gauge indicates that the A/C system pressure is lower than 10 PSI, it should be vacuumed prior to charging. If you do not know how to vacuum your A/C system, consult a professional certified technician.

  • When checking low-side pressure you will get two different pressure readings, one when the compressor cycles on and one when the compressor cycles off. Use the pressure reading when the compressor is cycled on and the system is operating at its highest settings (temperature to maximum cold and fan on high). When the compressor cycles on you should see the needle on your pressure gauge begin to drop. When the compressor turns off you will see the needle move back to a higher pressure. Take the reading that occurs when the pressure is at its lowest point when the compressor is cycled on.

  • Ambient temperature is simply the temperature of the air surrounding the car. Be sure to check out our Refrigerant Pressure Charts for more information.

  • Follow these steps, and always remember to wear safety glasses and gloves when recharging your vehicle’s A/C:

    1. Determine the ambient (outside) temperature before starting to charge your car. If the ambient temperature is 55°F or below do not charge the car. To determine the proper pressure of your car’s A/C, set the bezel on the pressure gauge to the outside temperature and then read the corresponding pressure setting on the gauge. If your gauge does not have a bezel dial with the corresponding temperature and pressure, consult the pressure temperature chart. After determining the proper pressure for your AC system charge to that pressure.
    2. Locate the low side port. Important note: Only charge your A/C system through the low side service port. Never use the high side port to add refrigerant. Doing so is dangerous and could cause you harm. If you are having trouble locating your low side port, try using our low port location finder by clicking here. If you still cannot find your low side port, locate the large diameter aluminum line coming from the back of your car’s compressor. The low side port will be located somewhere along that line between the compressor and the firewall. Still can’t find the low side port? Give our technical help desk a call at 1-888-318-5454.
    3. Remove the sealing cap from the low side port and wipe any dust from the port with a clean rag. Attach the hose to the low side port. Tug gently on the hose to insure a snug connection. Note: The hose will only connect to the low side port fitting. If the hose does not easily attach you are trying to connect it to the wrong port.
    4. Turn the handle clockwise until it will not turn anymore. This extends the piercing needle into the top of the can.
    5. Turn the handle counterclockwise to start the product flowing. By turning the handle counterclockwise the piercing pin retracts from the top of the can allowing the product to escape. To check the pressure, close the valve by turning clockwise until it will not turn anymore. Remember turning the handle so that it travels up is “open” and turning it so that it travels down is “closed.”
    6. Keep the can in the upright position when dispensing product. Rotate the can between the 12 o’clock and 2 o’clock position when charging. It is important to stop every 30-45 seconds to take a pressure reading on the system to prevent overcharging the system.
    7. When the A/C is charged to the proper pressure, close the valve on the top of the can and remove the charging hose from the low side port. Replace the sealing cap on the low side port. Store any remaining refrigerant in a cool dry spot in your garage.
  • No. The refrigerant in your vehicle’s air conditioning system never goes bad and never gets “used up,” so if your vehicle’s A/C system pressure is low it means there is a leak. This will need to be repaired in order for your vehicle’s system to hold refrigerant. If the system is able to maintain a charge for a period of two weeks or longer, it is possible to seal the leak with sealant such as A/C Pro® Super Seal. If it will not hold a charge for at least two weeks, it is recommended that a professional technician is sought out to help find and repair the leak.

  • Not only is overcharging your system potentially dangerous, but an overcharged system will also not function properly and can seriously damage your A/C compressor or other component parts. The symptoms of an overcharged A/C system are the same as a system that is undercharged: Warm air out of the vents.

    To prevent overcharging your A/C system it is imperative to measure the pressure before beginning to charge it. To measure the pressure in the A/C system, attach a pressure gauge to the low side port. Your car must be running with the A/C system set to maximum cool and the fan in its highest setting. It is important to note that the proper pressure in your A/C system is dependent on the ambient (outside) temperature. To determine the proper pressure for your system, consult a pressure chart such as this one, or set the bezel arrow on your pressure gauge to the corresponding ambient temperature and charge to the pressure corresponding to that temperature setting. If the outside temperature is at or below 55°F do not charge your car. Also, never charge your vehicle above 55 PSI.

  • Unfortunately, the caps on the high- and low-pressure automotive air conditioning service ports vary. In most cases, both caps will be black, but we have also seen them in gray, blue, and green. Sometimes they have an “H” or “L” to indicate high- or low-pressure ports.

    Wondering where your car or truck’s low-pressure port is located? Use our Port Locator.

  • No. Your car’s A/C refrigerant never goes bad. Nor do you “use up” the refrigerant that is in your system. If your vehicle’s A/C system pressure is low, your vehicle has a refrigerant leak and that leak will need to be repaired in order for your system to hold refrigerant. If your vehicle is able to maintain a charge for a period of two weeks or longer, then it is possible to seal the leak with sealant such as Super Seal. If your system will not hold a charge for at least a two week period then it is advisable to seek professional assistance to find and repair the leak.

  • Vent temperature will vary. Some newer cars may have vent temperatures that are below 50°F while older model cars’ vent temperatures may be in the mid-50’s to low 60’s.

  • Yes! This is one of the easiest jobs that you can do yourself on your vehicle. Please click through the following FAQs to learn how you recharge your AC using our products:

    Please feel free to call our technical support line for further help at 888-318-5454.

  • If the vehicle has a fully electric compressor (no belt-driven pulley) then you can use some of our products which have been developed specifically for hybrid and electric vehicles. As a rule of thumb, on hybrid vehicles you should ONLY use hybrid lubricant and straight refrigerant, however A/C Pro® has your back. Refer to our individual product pages for more information and to find what specific products can be used on your vehicle.

  • To properly charge you automotive A/C system the ambient temperature should be above 65ºF. Anything below that does not allow the system to build up enough pressure for a proper reading on your A/C Pro® pressure gauge. Because of this, adding refrigerant to your vehicle is not recommended when the ambient temperature is under 65ºF.

  • No. While our new universal gauges work with both types of valve systems, they do not make a piercing valve act like a self-sealing valve. If you are using a piercing can, you will want to keep your gauge attached to the can until it is depleted.

  • There are several possibilities behind why this is happening. One is that the compressor may be damaged and thus not working properly. You can check to see if it is cycling on and off properly by looking at the clutch faceplate in the middle of the compressor pulley. If your compressor is not cycling on, you should seek the help of a certified A/C professional immediately. Ignoring the problem will not make it go away and in fact can worsen the situation.

    Other possible causes are blown relays and fuses, defective sensors, and stuck blend doors. Seek the help of a certified A/C professional to assist in determining the cause.

  • No. Not only is it harmful to the environment to vent refrigerant into the atmosphere, it is also illegal. Violation of this Federal Law may carry a fine of up to $25,000. If you need to recover refrigerant from your system please seek the help of a qualified service technician.

  • The smiley face on the bottom of the can is a pressure relief vent to help release the pressure of the can should it become overheated. The refrigerant in the can is a high-pressure gas and, as with any gas, it expands when heated. You should never leave or store any cans of refrigerant in your vehicle as they can overhead and rupture the can. Always store cans of refrigerant in a cool, dry location.

  • The blue bezel turns on the gauge so that you can set the pressure range as it relates to the outside temperature. Here is how it works: determine the outside temperature around your car. Turn the bezel so that the arrow points to the outside temperature. Notice the “V” shape on the dial.

    This is the appropriate pressure range based on the ambient (outside) temperature. When reading the pressure, if the arrow is below the range then charge the car until the needle on the pressure gauge is in the range. If it is above the upper end of the range your system is overcharged. In this case you should seek the help of a qualified technician to recover refrigerant from your system to bring the system back into the proper range. Never vent A/C refrigerant into the atmosphere. It is harmful to the environment and illegal to do so.

  • Refrigerant and the additives that accompany A/C Pro® products do not expire or “go bad.” You can purchase or store an older generation can of refrigerant with the confidence that its contents are just as capable as a newly-packaged product.

  • The most common reasons the pressure gauge indicates a red/high pressure reading are either that the car is not running or the A/C is not on with the fan set to its highest setting and the A/C temperature set to its coldest setting. To obtain an accurate pressure reading, the car must be running with the A/C set to its coldest and the fan set to its highest. Also, as the car’s compressor cycles on and off, the needle on the gauge may move in and out of the red/high pressure area of the gauge. This is normal.

A/C Leak Sealers

  • If your vehicle’s A/C isn’t blowing cold it is likely low on refrigerant due to a leak. Most leaks are in rubber components such as O-rings, hoses, and gaskets.

  • The best way to find leaks is with our R-134a UV Leak Detection Kit (part # 436) which provides UV dye, high-intensity UV light and yellow tinted protective glasses.

  • Yes. The dye will not affect A/C performance.

  • Yes, the dye will continue to work the same way.

  • The leak sealer will take effect within 1 day of installation.

  • It of course depends on the nature of the leak, but typically leaks are sealed for approx 12 months of A/C usage.

  • They seal small holes that leak less than one can per month.

  • Your system will leak less refrigerant than it did previously. You cannot find a leak with the UV light that was there previously. Your system continues to blow cold air.

  • You should seek professional help.

Diagrams / Specs

DVA-1 Basics

  • Universal gauges never require a DVA-1.

  • Self-sealing valve gauges never require a DVA-1.

  • You will need a DVA-1 when using these R-134 products:








  • You will need a DVA-1 when using these R-134 products:








  • You will need a DVA-1 when using these R-134 products:









  • For retrofitting and top-offs, use products that include Polyol Ester oil. When rebuilding a system that has been opened and flushed, use a pourable PAG oil of the viscosity that is recommended by the compressor manufacturer.

  • When an A/C system leaks refrigerant, some oil escapes also. Our products all have the proper ratio of oil to refrigerant already blended to replace the lost oil.

  • Please click here to view the R-134a oil specifications by vehicle make.

  • Hybrid vehicle A/C systems use a special oil with electrically insulating properties is used to keep voltage from leaking to the compressor case through the oil. According to the hybrid manufacturers, if even a small amount of another (i.e., the incorrect) oil is introduced into the system, it may significantly decrease the electrical insulation properties which can cause compressor damage. The introduction of the wrong oil can cause a diagnostic trouble code to trigger which may disable the air conditioning system.

    Hybrid vehicle manufacturers also warn that if the wrong oil is introduced into and subsequently circulated through the system, all of the main A/C system parts (such as the evaporator, condenser, receiver/dryer, and compressor) should be replaced. It is recommended that a dedicated manifold gauge set be used when charging the system to ensure that any residual refrigerant oil left in the manifold gauges from refrigerant recovery on other vehicles does not enter the air conditioning system and deteriorate the insulating performance of the special oil.

Super Seal Leak Sealer

  • Any leak fixed by A/C Pro® Super Seal during a recharge creates a permanent bond that should not leak from that point again. In addition, A/C Pro® Super Seal will continue to flow through the air conditioning system as a lubricant and seal any new leaks that may develop, making it great for preventative maintenance.

  • One can of Super Seal is all you need to seal pin hole sized leaks in your system. In order to determine the size of your leak use the following rule of thumb: your car must be able to hold a refrigerant charge for at least two weeks. If you car can hold a charge for two weeks before blowing warm again, then Super Seal will be able to patch your leak. If you have a large hole or leak using two cans of Super Seal will not help.

  • Yes. The sealant technology in Super Seal has been used for decades in the underground gas transfer industry, sealing leaks in pipes, tanks, compressors, and other gas filled containers.

  • No! The chemical formulation in A/C Pro® Super Seal remains in a liquid state inside of the A/C system until it detects moisture at the leak point and self-seals. A/C Pro® Super Seal contains a drying agent to prevent any sealing activity while in the system and will be removed from the system along with the refrigerant should it ever leak out of be removed/evacuated.

  • Super Seal has a lower boiling point than the refrigerant oil. This enables the Super Seal to be removed from the system as the refrigerant either leaks out or is removed.

  • A/C Pro® Super Seal will repair most leaks in automotive air conditioning systems. However, the general rule is that if the system cannot hold a charge for 24 hours, the leak is too large and probably needs manual repair. If the system is leaking slowly and holds a charge for more than two weeks, A/C Pro® Super Seal should seal the leak. A/C Pro® Super Seal can seal multiple holes in both the metal and rubber parts of the A/C system and is an inexpensive alternative to having a mechanic work on the car, which could cost well in excess of $1,000.

  • Super Seal has sealed leaks in over 1,000,000 vehicles since its introduction in early 2000. This moisture activated sealant technology has long been used in the gas transfer industry, sealing leaks in pipes, tanks, and other gas filled containers.

  • While in the air conditioning system, it remains a liquid lubricant and contains additives to penetrate and rejuvenate o-rings, gaskets and other rubber connectors to prevent leakage. Included in Super Seal is a drying agent that gets rid of any moisture that may be inside the air conditioner. If the refrigerant leak occurs in a metal part, the refrigerant leaves the system and chills the outside air causing condensation. This moisture activates the Super Seal fluid to form a scab on the exterior of the metal.