Photograph of attic air conditioning air handler, condensate drips on floor Air Conditioning & Heat Pump Refrigerant Leak Repair Procedures

  • REFRIGERANT LEAK REPAIR - CONTENTS: How to diagnose & repair refrigerant leaks in the air conditioning or heat pump system. Leak repair tips for the HVAC cooling coil or evaporator coil; Causes of leaks in air conditioning or refrigeration equipment; How to find air conditioning leaks; How to fix air conditioning or refrigerator refrigerant gas leaks; Where do leaks occur in refrigeration equipment? Why do leaks occur in refrigeration equipment?
  • POST a QUESTION or READ FAQs about how to find and fix leaks in air conditioner or heat pump refrigeration piping systems

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Refrigerant gas or liquid leaks: this article discusses how to repair refrigerant leaks in air conditioning and cooling systems, using as an example, repairing a leaky or damaged air conditioning the cooling coil (evaporator coil) in the air conditioning air handler unit. Our photo at page top shows the cooling coil in the attic air handler component of a central air conditioning system.

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How To Repair HVAC Air Conditioner Refrigerant Leaks

AC system refrigerant access ports (C) Daniel FriedmanIf your air conditioning or heat pump system has lost its cooling capacity or won't start see REPAIR GUIDE for AIR CONDITIONERS.

As we explain in our articles on lost cooling capacity or air conditioning systems or heat pumps that are not working, a refrigerant leak in your air conditioner or heat pump means that eventually it will just not produce cool air (during air conditioning) nor warm air (during heating if it's also a heat pump).

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First we need an accurate diagnosis of the air conditioning problem. If your air conditioning or heat pump system has lost cooling (or heating) capacity, there can be various causes besides loss of the refrigerant in the system.

  1. First, see LOST COOLING CAPACITY to diagnose just why the system is not working.
  2. If you know that the refrigerant level is low or zero, don't just re-charge the system. Find and fix the refrigerant leak. See REFRIGERANT LEAK DETECTION. While it's quick (and cheap) to just add refrigerant to a system, we were taught at HVAC school to scorn earning a living by developing a refrigerant gas delivery route.

    An air conditioning or heat pump system is normally completely sealed and should never "use" refrigerant. Refrigerant gases are not a substance which is "consumed" in an HVAC system.

    In an emergency, such as at a commercial establishment needing time to move frozen food, one might just add refrigerant, but the proper repair is to find and fix the refrigerant leak.
  3. If the refrigerant gas leak is in a valve or access port, such as the service ports to which the HVAC technician connects her gauge set, the valves there may be able to be cleaned and salvaged, or the valves may need to be replaced.

    Replacing a refrigerant gas service port valve is a soldering job similar to what we describe just below. In our AC repair career we never had to replace one of these valves but we did have to install them on some systems where they were not already in place.

    Our photo at left shows refrigerant gauge access ports on a compressor/condenser unit.
  4. If the refrigerant gas leak is in the air conditioning or heat pump copper tubing a repair should be easy - the damaged line is re-soldered using high silver content solder and a high temperature torch. (We used MAPP gas for silver soldering of copper fittings, some technicians use Acetylene or other gases).

    A damaged section of refrigerant line may need to be cut out and replaced. The repair is about the same regardless of whether the leak was in the larger diameter suction line or the smaller diameter high pressure line.

    Details about refrigerant piping installation or replacement are at REFRIGERANT PIPING INSTALLATION.
  5. If the refrigerant gas leak is in the condensing coil or in the evaporator coil, repair might be possible, but we're less optimistic that repair is possible, but it might be, as we explain just below.
  6. Use a halogen gas leak detector to pinpoint refrigerant gas leaks and for thorough inspection & testing of the entire refrigerant piping system, including the condensing and evaporating coils. Details are at Using the TIF 5000 Gas Detector.

Should We Just Add Refrigerant Rather Than Finding and Fixing the Leak in our Air Conditioner or Heat Pump?

Photograph of a
commercial air conditioning compressor charging gauge set (C) InspectAPedia.comAt HVAC school we were taught that some HVAC technicians, in the opinion of the instructor (and our own as well), like the idea of a "delivery route" business, coming around periodically to replace lost refrigerant. In our view in many circumstances this can be a questionable practice.

Air conditioners and heat pumps are designed as a closed, hermetically sealed system - they are not supposed to leak refrigerant, and refrigerant leaks are an abnormal condition. The refrigerant leak can be found and repaired.

If the technician was in a hurry, perhaps given many service call assignments, or if s/he didn't want to be hassled by a customer complaining over an "attempt convert a simple recharge to a costly service call", or if the company just likes to deliver refrigerant (lots of repeat business), or finally, if the system with the refrigerant leak is large, commercial, complex, and old - at end of life, s/he may not have mentioned that refrigerant leak repair is even possible.

If you are faced with a costly service call or repair on an old air conditioning system (such as the need to replace a corroded, leaky evaporator coil) on a system that is at or near end of life, it is understandable that you might just prefer to wait and replace the whole system.

But it is not air conditioner or heat pump system age that makes a refrigerant leak able to be found or not, it is system complexity. Sometimes, especially with large complex commercial systems, because tracing all of the piping and tubing and looking for leaks is time consuming, some people opt to just add refrigerant.

Just adding refrigerant is not the best practice. And with old freon-based cooling or heat pump systems such leaks might be illegal as you are damaging the environment and making a prohibited release of Freon gases to the air.

The refrigerant gauge set photo above is discussed in detail at GAUGE, REFRIGERATION PRESSURE TEST.

Guide to Repairs of an Air Conditioning or Heat Pump Evaporator Coil or Condensing Coil

Sketch of a cooling coil (C) Carson Dunlop Associates

  1. Review the coil inspection, diagnosis, and repair tips at COOLING COIL or EVAPORATOR COIL. We find that the terms "cooling coil" and "evaporator coil" are used as synonyms in most cases. Sketch at left courtesy of Carson Dunlop Associates.

    Even if the cooling or condensing coil has a repairable leak, if the coil is badly damaged such as having all crushed fins, it may be best to replace it.

    Damaged cooling / evaporator coil fins over more than 10% of the coil surface, blocking air flow may be a reason to replace the coil.
  2. If the cooling coil or condensing coil is in good physical condition but it's dirty, it needs to be cleaned before it can be repaired. Spray-on coil cleaners are used by lots of HVAC technicians.

    If the coil is dirty with moldy dust and debris and especially if the building is occupied by people at extra health risk, we don't like to see an indoor coil cleaned by blowing it off with compressed air, as you're simply sending all of this moldy junk into the building. See DIRTY COOLING COIL and see Mold Growth in Air Handlers. You may also want to check out Leaks, Rodents In Air Handlers.
  3. Next check the cooling coil or evaporator coil for visual evidence of refrigerant leaks. Visual evidence of a refrigerant leak on a coil may include stains from refrigerant oil left at the point of leakage. See REFRIGERANT LEAK DETECTION.
  4. When the one or more places where the cooling coil or evaporator coil is leaking refrigerant gas have been found, it's time to decide if we can perform a solder repair of if the coil has to be replaced. We offer some suggestions just below at Guide to Evaluating Evaporator Coil or Condensing Coil Refrigerant LeakS

Guide to Evaluating Evaporator Coil or Condensing Coil Refrigerant Leaks and Deciding to Repair or Replace a Coil

Sketch of an air conditioner or heat pump evaporator coil (C) Carson Dunlop Associates

Evaporator coil or cooling leaks or holes: if an evaporator coil is leaking (or also if the condensing coil is leaking) you'll find out pretty quickly as refrigerant will be lost and the cooling system will stop providing cool air.

You'll need expert diagnosis by an HVAC service technician. Sketch at left courtesy of Carson Dunlop Associates.

  • How easily a cooling system refrigerant leak repair will be depends on where the refrigerant leak has occurred and what caused the leak.

    If the cooling coil has a single point leak caused by some mechanical damage (one of our readers accidentally drilled a hole in his coil while trying to drill a drain hole in his air handler), it may be possible to find the hole and repair it using silver solder.
  • If the refrigerant leak is in copper tubing anywhere in the cooling or heat pump system that is not too close to an evaporator coil or condensing coil, it should be possible to solder a repair, then evacuate and recharge the cooling system.
  • If the refrigerant leak is in thin copper tubing that just melts when you try to solder it, as suggested by one of our readers, your technician may fabricate a copper sleeve that slips over the damaged tubing and is then soldered in place.
  • If the refrigerant leak is in copper tubing in or close to the cooling coil (or in a condensing coil) a solder repair is hard to complete because the heat of the soldering process tends to de-solder other nearby connections. It might be possible if the technician is very expert and if s/he knows how to keep nearby surfaces cooled (we've used a wet rag).
  • If the refrigerant leak is in an aluminum part, soldering aluminum is more tricky and may not be feasible. Ordinary procedures using a torch, for example, just melt the aluminum. Expert welders use inert gas welding methods.
  • If the refrigerant leak is due to severe corrosion anywhere in an HVAC system we're not optimistic that a solder repair is possible. The conditions that caused a corrosion-related leak are likely to have thinned and weakened other parts. The cost of an attempted repair may be wasted.

Replacement of the cooling coil (or condensing coil) is more often going to be recommended by your HVAC technician because of these difficulties.

Bubbles seen or heard in the liquid refrigerant line?

Clean Dust & Dirt Off of the Condensing Coil - Air conditioning and refrigeration performance &maintenance tip

Refrigerant sight glass use to check for low HVACR refrigerant (C) Carson Dunlop AssociatesAs we also introduce at CONDENSING COIL REPAIR REPLACE, there is a big payoff in cleaning dust, debris, grass clippings off of a dirty refrigeration condensing coil (this includes outdoor condenser/compressor units for air conditioners and heat pumps and also the condensing coil on a home refrigerator or freezer).

Because a refrigeration system works by transferring heat from hot refrigeration gas/liquid to ambient air around the condensing coil, if the condenser coil is blocked by dirt and debris, this can prevent complete cooling of the high temperature refrigerant gas back to a liquid state.

The result is you'll get refrigerant gas bubbles passing through the refrigerant metering valve. On refrigeration systems that include a sight glass you can actually see these gas bubbles passing through the system.

More details are at REFRIGERANT SIGHT GLASS.

Incidentally a second source of bubbling sounds heard in the refrigerant piping suction line near the compressor could be refrigerant oil pooling in that location.

This oil pooling is not usually a consequential problem provided the collection of oil does not block passage of refrigerant in the system. In good HVACR design the refrigerant piping slopes back from the evaporator unit (cooling unit or air handler) towards the compressor/condenser unit so that refrigerant oil in the line finds its way back to the compressor motor.

Recharging the HVAC System after Refrigerant Leak Repair

In case you didn't realize it, in order to solder a repair in an air conditioner or heat pump piping, tubing, evaporator coil/cooling coil, or condensing coil, it will first be necessary to remove all of the refrigerant from the system.

The HVAC technician will connect a pump to pull a vacuum on the system to remove as much air, gas, debris, and moisture as possible. An evacuator pump is needed for this step. [We made our own vacuum pump using a particularly good performing Frigidaire rotary compressor retrieved from an abandoned antique refrigerator.]

The HVAC technician will probably want to install a refrigerant filter/drier (see our photo below) to remove any moisture that leaked into the system while it was open to the atmosphere, and perhaps she will install other filtration equipment on the system at this time. It's a good idea.

See GAUGE, REFRIGERATION PRESSURE TEST for details about the refrigerant charging procedure using a gauge set and charging cylinder or scale.

Installing a Refrigerant Drier / Debris Filter after Piping Work or System Evacuation/Re-charge

Watch out: good practice following work on refrigerant piping systems or system evacuation and recharging withn refrigerant includes the installation of a debris filter and refrigerant drier device.


Decision to Replace an HVAC Cooling Coil or Evaporator Coil & Replacement Costs

If the decision is to replace the cooling coil or the evaporator coil, be sure that the new coil is the proper size and shape to match the condenser or evaporator unit itself.

Reader Question: should I try to fix a leaky refrigeration coil on my air conditioner?

3/27/14 Mike said:

My air conditioner is 8 years old. The system is leaking refridgerant at a slow level and the hole is midway through coil. Should I try to fix the coil or opt for a new unit?


Some AC coils can be repaired using epoxy but I am not optimistic about this approach. Here are some considerations:

If the coil leak was caused by an accident, like a mechanical puncture, repairing it might yield a durable remaining life for the system provided we don't contaminate (or contaminate and fail to clean) the refrigerant piping system in the process.

If the AC coil leak was caused by vibration and rubbing or by corrosion I fear that fixing the leak in one place is a band-aid repair that won't give a durable repair since other leaks are coming soon. It's the beginning of the end.

If the HVAC system is relatively new so that it uses modern contemporary refrigerants, then replacing the coil is a plausible repair and the recommended one. The system will have to be evacuated, cleaned, new refrigerant installed along with appropriate refrigerant dryer/filters.

If the HVAC system were old enough (probably not your case) that it still uses R22, repair people either take another band-aid approach by replacing the ruined coil with an R-22-rated coil and R22 refrigerant (no longer a proper repair as this refrigerant has been phased out of use) OR the technician may be tempted to install a new coil rated to use a new refrigerant.

But that last approach leads to more costs: a coil mis-matched to the rest of the equipment will operate very poorly, as demonstrated by

and when we change refrigerant we may need to change additional controls (TEVs for example) increasing the job cost until it begins to look as if a complete outdoor compressor/condenser unit replacement or even a whole system replacement would have been a smarter change.

For an example of coil replacement costs see our condensing coil replacement discussion at CONDENSING COIL REPAIR REPLACE .

Continue reading at REFRIGERANT PIPING INSTALLATION or select a topic from the More Reading links shown below.

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