Category: A/C system leaks

a/c stop leak good or bad

A/C Stop Leak products ?

A/C Stop Leak products ?

Refrigerant must be 99% or more, pure, anything less than this value is considered a contaminated refrigerant and therefore contaminated automotive air conditioning system. Any warranty on the car’s ac system will be automatically void if any type of sealer is found in the system.

A/C stop leak.

Vehicle and A/C part manufacturers do not endorse the use of sealants. Sealant is made to plug small holes by hardening when it contacts the moisture in the air. The problem is that a leaking system has absorbed a lot of moisture and spread into every component of the air conditioning. The sealant reacts with moisture inside a condenser or other component, creating a restriction in the normal flow of refrigerant. They will weaken rubber parts, have no effect at all, or create larger particles that will clog the filters, orifices tubes, screen protections and other parts of the AC System.

Flushing the sealant out from the ac system.

Once installed it is difficult, if not impossible to remove all the sealant from the system. There is a big risk of contaminating and damaging a new ac compressor even after the entire system has been flushed. Some air conditioning components like parallel flow condensers or evaporators are virtually impossible to effectively flush. An small and inexpensive service valve core leak could become a time consuming repair job because of the use of a/c stop leak products.

Contaminated refrigerant symptoms.

Some of the symptoms of a contaminated air conditioning system are: reduced cooling performance, evaporator ,thermal expansion valve or orifice tube freeze-up, intermittent cooling, increased compressor noise, higher than normal or lower than normal pressures, and premature compressor failure.

Motor Vehicle AC repairs.

Many shops will refuse to even connect their recovery machine to your car’s ac system if they suspect the use of sealant. Sealants could do really expensive damage to recovery equipment creating a huge problem for repair shops.

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ac temperature out of the vents

How often does an AC system need to get recharged?


The A/C system in your car is a closed sealed system. It may never need to be recharged. The refrigerant inside the system is pressurized by the hvac compressor ,recirculated and reused in a closed loop infinite system. The Freon(refrigerant) will change from vapor to liquid and back constantly for as long as the system is running.

The R-134a/R-1234yf install in your car is in charge of moving the unwanted elevated temperature of one room or space (the cabin inside your car ) to the outside ambient temperature where it has no impact. To accomplish this task properly a factory calculated range amount of refrigerant needs to be running inside the system.

You need to get your AC system recharged as soon as the total amount of refrigerant is too low to carry the heat from inside your car’s cabin to the outside of the vehicle.

100 % sealed air conditioning system does not exist. All a/c systems leak, and this condition is taken into consideration when the a/c charge amount is calculated when designing the system. Some amount of refrigerant loss could develop over time, but it is a minute amount, and it should not affect system operation.

How do I know if my ac in my car needs to be recharged ?

There is not a periodic service interval that you need to follow to recharge your air conditioning system. This service is system dependent, meaning every car will have unique needs for freon(refrigerant) recharge.

The first sign that could indicate that you need to recharge the refrigerant in your car’s ac system is when the system begins to cool less than it used to.


  • Poor A/C performance. A/C not cooling down the vehicle
  • One Side of the car cooling more than the other side.
  • Back of the car cooling more than the front.
  • A/C compressor short cycling. A/C compressor turning on and off fast.
  • Frost in a/c lines.
  • Visible refrigerant (Freon) leaks.


Low refrigerant could mean low oil circulating and improper lubrication of the hvac compressor. Therefore when there has been a refrigerant leakage big enough the compressor gets to the point where there is not refrigerant to pump and then it pumps out the oil that lubricates the compressor’s internal components. Failure of the a/c compressor will result if the ac system is not recharged, and oil balanced properly.


Automotive air conditioning system.A/C lines.


If moisture enters the A/C system, it mixes with the refrigerant to form harmful acids. These acids damage the ac components from inside out.


How to prevent acids from forming.


The method of removing any moisture from the A/C system is to pull a deep vacuum on the system. Pulling a deep vacuum on the system, will cause any moisture to vaporize and be pulled out of the system.

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r1234yf refrigerant tank

What is the refrigerant used in AC?

R-134a and R-1234yf are the refrigerant found in the automotive indurstry.R-12 was used in older cars built before December 1995 but is no longer used.

R-134 and R-1234yf are chosen for its low  Ozone depletion potential ODP ,its low flammability and toxicity. These refrigerants do not contain chlorine and have no Ozone depletion potential. Automotive refrigerants have a very low Global Warming Potential GWP and have a minimum impact in the environment when used properly.

What is the best AC refrigerant?

The best A/C refrigerant are those that get the job of cooling the interior of your vehicle down in the most efficient way with the minimum contamination impact on the environment. To be a good ac refrigerant candidate in the automotive industry must have some additional safety characteristics like low flammability and low toxicity.

How often does AC refrigerant need to be replaced?

The A/C refrigerant needs to be replaced as soon as the system must be opened to do service to the air conditioning system or when a leak is developed in any component of the auto ac system.

The a/c refrigerant in the auto ac system is in a virtually endless closed loop and does not have to be refill or replaced. The auto a/c system major components are designed in a way that the ac refrigerant cycles repeats endlessly with refrigerant changing state from gas to liquid and in the change of state process cooling down the interior of your vehicle.

Who can refill the ac refrigerant in my car ?

Only (EPA) certified technician can refill the ac refrigerant in you car.

The United States Environmental Protection Agency (EPA) regulates section 608 of the Federal Clean Air Act. Failure to comply could cost you and your company as much as  $27,500. Per day per violation and there is a bounty of up to $10 000 to lure you competitors , customers, and fellow workers to turn you in.

Specific recovery techniques and tools are required to properly and environmentally friendly refill the ac in a vehicle.

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A/C low pressure & high pressure service valve ports

Car a/c service ports.

Most Air conditioning systems use Schrader valves at their service ports. These valves are similar to tire valves, although they can never be interchanged. They are covered with caps (resembling tire valve caps), containing O-rings.

Unless the system has been completely discharged due to a leak, recover the refrigerant using the appropriate method and equipment before servicing any hose , line, or fitting.

Which port do you charge AC in car?

Although charging the system can be performed through either the high side or low side when the engine is not running, it must be done only through the low side when the engine is running. This safety measure prevents the high-side backpressure from entering the refrigerant container and possibly causing an explosion.

Use the manufacturer’s specification for refrigerant capacity. On most newer vehicles, a sticker is affixed in the engine compartment indicating the type of refrigerant , type of oil, and the refrigerant capacity of the system.

How do you add freon to your car’s air conditioner ?

The most accurate method to assure that the proper amount of refrigerant has been added to the system is to use a charging station that can be programmed to deliver a specified amount. It is crucial that the exact amount of refrigerant according to specifications is used. Overcharging the system can cause damage, and undercharging will cause poor performance.

Where is the AC service port?

The location of the ac service port will depend on the make, model, year, and refrigerant type of the vehicle. The easiest way to find the ac service port in any car is to follow the lines from the compressor all the way into the firewall. The A/C service ports will be at some point between the ac compressor and the firewall.

Are all AC service ports the same?

The low side service port the  is the smaller of the two ac service ports. In all car new models, the high side fitting and low side fitting are different diameters .This prevents connecting the service hose to the wrong fitting. Systems with different refrigerants also require differently designed service fittings. This is to discourage technicians from putting incorrect refrigerant or oil in a system and contaminating it. Do not try to circumvent them with adapters.

R-134a refrigerant systems use quick-connect fittings, like the type used on air tools, and this time the low side port is smaller of the two.

R-1234yf refrigerant systems use quick-connect fittings too, but with different diameter to prevent contamination with R-134a refrigerant systems.

Some older systems have three-way stem-type service valves at the compressor inlet and outlet ports.

Your service tools must have the proper connectors for the various service fittings, and the equipment used on one system should not be used on another.

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Auto A/C Evaporator Failure Symptoms

Auto A/C Evaporator Failure Symptoms

Auto A/C Evaporator Failure Symptoms:

  • When the evaporator core is leaking, the ac system performance is greatly decreased.
  • The driver and passengers start to smell refrigerant from the cabin vents.
  • In cars with dual ac units another sign is that the front unit stops blowing cold air first while the back unit still blows some cool air.
  • in cars with front ac unit only, the vents from one side of the car blows colder than the other one.
  • Compressor cycling on and off too often.
  • A/C compressor inoperative due to low refrigerant condition.
  • Weak air flow if evaporator core surface is restricted with debris.
  • Low air conditioning system pressures.
  • Air conditioning system freezing up at high engine speed.
  • Pressure and temperature sensors prevent the a/c compressor from engagement.

How to fix an auto a/c evaporator core failure.

The evaporator core can’t be repaired, it must be replaced. Usually, the evaporator core is not an expensive part, but because is deeply buried underneath the dash is a very hard to reach component and time-consuming repair. In most cases the whole dashboard and center console must be taken apart to get to the hvac box.

Car Evaporator core leak and low A/C oil condition.

When the evaporator is leaking refrigerant ,the oil that lubricates the a/c compressor internal components will leak out as well. If the a/c system is only recharged with refrigerant without replacing the evaporator core, the compressor will be running low on oil. The a/c refrigerant and oil lubricate and cool down the automotive a/c compressor. Running the a/c compressor low on oil and refrigerant will eventually damage the air conditioner compressor. A leaking evaporator must be replaced and the oil must be balanced to ensure all components are properly lubricated.

Auto A/C Evaporator core repair near me.

If you need assistance replacing the evaporator coil in your vehicle, Call Us Today. We operate in all Miami-Dade County area.

car ac evaporator

Car A/C Evaporator Core Repair.

The Car A/C Evaporator’s job is to remove heat and humidity from inside the vehicle. Heat and humidity is transferred to the outside of the vehicle by the ac system refrigerant; as warm moist air passes over the aluminum fins of the cool evaporator, heat is transferred from the air to the evaporator. The moisture contained in the air, condenses on the evaporator surface. Dust and pollen passing through the evaporator stick to the wet surface and then drain to the outside of the vehicle. The water can often be seen dripping from the bottom of the vehicle on humid days when the a/c system is operating.

After the expansion valve or orifice tube ,inside the evaporator, the pressure of the refrigerant is allowed to decrease from the high pressure of the liquid refrigerant to a very low pressure. This pressure change inside the evaporator causes the refrigerant to boil, or evaporate. The latent heat of absorption from this state change makes the evaporator cold and allows it to pick up excess heat from the outside air or re-circulated air before it reaches the passenger compartment.

How much does it cost to replace an evaporator coil?

The Car A/C Evaporator core can’t be repaired, it must be replaced. Usually, the evaporator core is not an expensive part, but because is deeply buried underneath the dash is a very hard to reach component and time-consuming repair. In most cases the whole dashboard and center console must be taken apart to get to the hvac box.

The cost for replacing the evaporator core will depend on the make, model, and year of the car. The price range is from about $700.00 to $2000.00 dollars.

What are the symptoms of a bad evaporator core?

Refrigerant Leakage often happens because leaves or other organic material enter the evaporator case through the exterior air intake vents and come in contact with the evaporator’s surface, this moisture surface and decomposition of organic materials, can form corrosive substances which could eventually damage the evaporator core. Moisture inside the system interacts with the oil and refrigerant and creates corrosion inside the evaporator core damaging it from the inside out.   The evaporator fins are also susceptible to clogging from leaves or hair from pets and other outside road debris.


When the Car A/C Evaporator core is leaking, the ac system performance is greatly decreased.

The driver and passengers start to smell some particular odor that is often described as the odor coming from a room that is been locked in a long time.

In cars with dual ac units another sign is that the front unit stops blowing cold air first while the back unit still blows some cool air.

in cars with front ac unit only, the vents from one side of the car blows colder than the other one.

Compressor cycling on and off too often.

What is evaporator core in car AC?

The AC evaporator is one of the heat exchanger in your car. It resembles the condenser but is much smaller and usually more difficult to access it inside the hvac case for repairs. They are generally of the tube and fin design. The evaporator can be thought of as a heat sponge. It creates, together with other ac components in the vehicle a comfortable in cabin air temperature. Typically, when the body is at rest (sitting) and in surroundings of 75 F and 50% humidity with a slight air movement, the body is close to being comfortable.

What is the function of evaporator in air conditioner?

The evaporator works with other components in the A/C system to maintain the pressure and temperature of the evaporator to desired levels. These components can vary, but their main function is the same-they keep the pressure in the evaporator low and keep the evaporator cold without allowing freezing. Some A/C systems use a temperature sensor to prevent evaporator freeze-up by shutting off the compressor.

What is the difference between an evaporator and a condenser?

The evaporator core and the condenser coil both are heat exchangers devices. The main difference between the evaporator core and the condenser is that the evaporator core absorbs heat into the system, cooling down the surrounding air; the condenser on the other side rejects heat created by the compression action of the ac compressor and the heat in the area been cooled.

What state is refrigerant in in the evaporator?

Inside the evaporator core the refrigerant enters as a mixture of about 75% liquid and 25 % vapor. The ideal temperature of the evaporator is approximately 34 F. To maintain this temperature, low pressure liquid refrigerant is metered into the evaporator. As this happens the refrigerant changes state from a liquid to a vapor and cools the evaporator. Warm air is directed over the evaporator from the hvac blower fan, and then the heat in the air is transferred to the refrigerant in the evaporator. This heat is then carried off with the refrigerant to the outside of the vehicle.

Where is located the evaporator core?

The ac evaporator core is located inside the hvac box underneath the dashboard of your car. The temperature of the coil is lower than the in-cabin air temperature being pushed thought it by the action of the blower motor, because of this the evaporator is able to absorb the heat from the passing air and lower its temperature and humidity.

The evaporator absorb heat from the medium being cooled.

Allow the heat to boil off the liquid refrigerant to a vapor in its tubing bundle.

Allow the heat to superheat the refrigerant vapor in its tubing bundle.

Filters the air and get rid of road debris and other forms of contamination from inside the car.

Dehumidify the air and adjust the humidity to level more comfortable to the human body.

What happens to refrigerant in the evaporator?

The refrigerant coming from the metering device enters the evaporator coil from the bottom as a mixture of about 75% liquid and 25 % vapor. Evaporators are usually fed from the bottom to help ensure that no liquid leaves the top without first boiling off to a vapor. If they were fed from the top, liquid could quickly drop by its own weight to the bottom before it is completely boiled off to a vapor. This protects the compressor from any liquid refrigerant.

About halfway up the coil, the mixture becomes more vapor than liquid. The purpose of the evaporator is to boil all of the liquid into a vapor just before the end of the coil. This occurs approximately 90% of the way through the coil, leaving pure vapor.

At the point where the last droplet of liquid vaporizes, we have what is called a saturated vapor. This is the point where the vapor would start to condense if heat were removed from it or become superheated if any heat were added to it.

What are the types of evaporators?

Numerous types of evaporators are available, and each has its purpose. The first evaporators for cooling air were of the natural convection type. They were bare-pipe evaporator with refrigerant circulating through them. The stamped evaporator was one of the first designs to create a large pipe surface.

Types of evaporators

Aluminum parallel-flow ,flat-plate-and-fin evaporator

Forced-draft evaporator

Finned-tube evaporator

Drum-type evaporator

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Air conditioning car system O-ring leaks

Air conditioning car system O-ring leaks

Air conditioning car system O-ring leaks

Air conditioning car systems are sealed at every connection using O-rings to avoid the refrigerant from venting into the atmosphere. O-rings are used at every connection of the air conditioning system creating a sealed system. The seals can withstand variable or constant pressures, high and low temperatures, preventing the venting of the refrigerant into the atmosphere.

The most common causes of a car O-ring failure and A/C leaks are the following

  • Incompatibility between the O-ring material and the fluid it is to seal.
  • The wrong O-ring size.
  • Improper O-ring installation.
  • Gland or cavity deformation.
  • O-ring dry installation or using the wrong type of lubrication

Car O-ring tools & installation to avoid air conditioning system leaks.

The use of the proper tools for O-ring installations are critical to avoid any damage to the O-ring surface. The use of sharp-edged tools, passing the O-rings over sharp threads, lack of lubrication and use of poor quality O-ring materials are the main causes of O-ring damage and possible air conditioning leaks. It is recommended the use of picks for removal & installation of the O-rings. Always lubricate the O-ring with the right type of oil and cover sharp threads before passing the O-ring over. Choosing the right size of O-rings for every application in the air conditioning system is crucial.

Where do most car AC leaks occur?

All sealed auto systems leak. Concentrate your efforts at car ac system connections and fittings as these are the most likely leak sites.

Every pressurized system leaks, because flaws exist at every joint fitting, seam, or weld. These flaws may be too small to detect with the best of leak detection equipment. But  given time, vibration,  temperature and environmental stress, these flaws become larger, detectable leaks.

It is technically incorrect to state that a unit has no leaks. All system has leaks to some degree. A sealed system which has operated for 10 years without ever needing a charge is called a tight system. The system still has leaks, but not enough leakage to read on a gauge or affect cooling performance. No pressurized system is perfect.

Refrigerant escapes at different times and at different rates. Leaks may plug, and then reopen under peculiar conditions. A leak is a physical path or hole , usually of irregular dimensions. The leak may be the tail end of a fracture, a speck of dirt on a gasket, or a microgroove between fittings  

Types of auto ac refrigerant leaks

Types of leaks:

  • Standing leaks
  • Pressure-dependent leaks
  • Temperature-dependent leaks
  • Vibration-dependent leaks
  • Combination-dependent leaks.
Standing leaks

Passive leaks are leaks that can be detected while the unit is at rest of off. Standing leaks are the most common of all leaks.

Pressure-dependent leaks:

Pressure dependent leaks are leaks can only be detected as the system pressure increase.

Temperature-dependent leaks:

Temperature-dependent leaks are associated with the heat of expansion. They are usually due to high-temperature ambient air or condenser blockages or restrictions in the ac system.

Vibration-dependent leaks:

Vibration dependent leaks only occur during a/c system operation. The mechanical strain of motion, rotation, refrigerant flow , or valve actuation are all associated with vibration-dependent leaks.

Combination-dependent leaks:

Combination dependent leaks are flaws that require two or more conditions in order to induce leakage.

How can I find where my AC is leaking?

Electronic Leak detector procedure according to EPA:

When using an electronic leak detector ,always follow the manufacturer’s operation instructions. In addition to the manufacturer’s instruction, the following should be observed

  1. Always leak test with the engine off
  2. Only a small amount of refrigerant is required to perform a leak test. A gauge reading of 50 psi is all that is needed. At temperatures below 50 F ,leaks may not be measurable , since 50 psi may not be attainable.
  3. To avoid contaminating the tip of your leak detector, remove excessive dirt from suspected leak areas. Do not use cleaners or solvents, your detector may be sensitive to their ingredients.
  4. Visually inspect the system , and look for signs of air conditioning oil leakage , damage , and corrosion on all lines, hoses and components . Each suspected area should be carefully checked.
  5. Follow the system around in a continuous path to ensure that no areas are missed. If a leak is found , continue to check the remainder of the system for additional leaks.
  6. At each area checked , move the probe tip around the location 1” per second while holding the probe no more than ¼ inch above the surface of the area being leak checked.
  7. To verify an apparent leak, blow shop air into the area of the suspected leak to clear any refrigerant that may linger and repeat the leak check

Alternate methods:

An alternative method of leak testing is to use Nitrogen to pressurize the system, then pin-point leaks with a soap and water solution.

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