Questions & answers about finding & fixing air conditioning, heat pump or refrigerator / freezer refrigerant gas or liquid leaks:

FAQs about how to repair refrigerant leaks in air conditioning, heat pump, or other refrigeration systems.

This article series 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.

Questions & Answers on How To Repair HVAC Air Conditioner Refrigerant Leaks

These questions and answers about finding and fixing refrigerant leaks in air conditioners, heat pumps, refrigeration equipment were posted originally at REFRIGERANT LEAK REPAIR - please be sure to see the advice given there.

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Question: Did corrosion cause this refrigerant leak in piping at the compressor?

2019/01/28

The contractor did not purge the line set before brazing, and did not pressure test after, so he discovered a leak on the liquid line upon opening the valves on the compressor/condenser unit.

While R410 spewed from the leak, the tech rebrazed the liquid line

Now 5 years later, the system develops a leak, which appears to be from corrosion, but the contractor claimed, in court, that the leak was caused by vibration.

I cannot find any literature citations which discuss the causes and effects of corrosion on heat pump systems. Any guidance would be helpful. - Anonymous by private email 2019/01/28

Reply: Common causes of a refrigerant leak include & extend beyond corrosion

Vibration OR a poor initial brazing connection ( or both ) is more likely to cause a leak in refrigerant piping except in the most-extreme case of corrosion.

I see no obvious corrosion on the piping exterior in your photo.

I do see that the leak is close to the point at which what looks like a swaged copper line is brazed to the compressor motor. The root problem could be any of several of the more broad list I give below of

Common Causes of Refrigerant Leaks

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- damaged or over-thinned copper flare or swage due to swaging to expand the copper line to fit the compressor's fitting: flare too small, flare over-thinned, flare ridged during preparation

- overheating during brazing

- incomplete braze joint, e.g. from inadequate cleaning of the joint or inadequate or improper flux or brazing rod application

- vibration possibly combined with absence of a flexible copper bend to dampen vibration effect (more-difficult or less common in heavy piping installations)

- corrosion inside or outside the line (not visible)

- other refrigerant piping installation errors described

at REFRIGERANT PIPING INSTALLATION

- sealant on threads; improper use

- missing caps on refigerant fittings such as gauge ports or TEV adjustment cap

- missing O-rings in fittings or caps

But note in your refrigerant leak photo close-up above (my enlargement) that the pattern of the refrigerant leak revealing spray appears to have a linear shape close to the tubing, suggesting a crack or open braze joint rather than a more-round or pinhole corrosion leak.

I suspect that an examination of the piping interior - if it were cut away to permit inspection - would not show significant corrosion, since in my OPINION if corrosion were the cause of this leak, by the time it perforated the tubing or piping you'd see very thin copper around the perforation and visible corrosion - probably green.

Vibration is a particular leak risk when there we have both heavy tubing - resisting flexing or bending. A bad or loose motor mount could be a factor too.

You'll see on many installations where smaller lines are involved there's an extra bend or length to permit some movement without breakage.

I'll do some research on corrosion studies.

Reader follow-up:

Your evaluation seems rational, and conforms with my own understanding of broad corrosion patterns, particularly with regard to the thinning that normally occurs

. I did not expect this to be corrosion from an outside source, and we did not cut the leak out for examination, which would be the only way to confirm the mechanism by which the leak occurred. However, the leak appears to be within the heat affected zone of prior brazings.

We know that heating changes the orientation of drawn copper tubing, and can make it susceptible to other contaminants, such as flux, which might have been on the interior surface when the heating occurred.

Such a potentiated localized site would then be susceptible to pinhole corrosion, in this case perhaps facilitated by high velocity gas flow sweeping the outside of the curve. The piping itself has two long radius curves over a net fall of 26 inches, and the compressor is firmly shock mounted.

There is obviously high frequency vibration being transmitted to the piping extending out from the compressor, a Copeland Compliant Scroll, but I have difficulty understanding how such vibration can separate the silver/copper bond, which is rated at some 15,000 psi tensile strength.

Have you seen actual evidence of such failures? Perhaps cutaway views of the separated area?

Also, I cannot find any significant information on the consequences of brazing refrigeration lines when they contain refrigerant and polyolester lubricant.

I did find that valeric acid based esters have a thermal decomposition temperature range starting at 530*F, which is why the manufacturers urge that newly installed systems be leak checked and evacuated before any refrigerant is introduced to the indoor coil side of the system (for split system heat pumps).

Can you steer me to some research on the likely decomposition products of the thermal breakdown of polyolesters?

Would this brazing temperature break down R410? The mechanism of mineral acid corrosion would be different from organic acid attack, and is known to slightly favor pinhole type attacks largely due to electrochemical factors which are less important in organic acids.

The electrochemical factor is probably diminished somewhat in an environment which is largely free of water, thus inhibiting extensive dissassociation and significantly lower pH.
Thank you for your time and interest in this matter.

Mod reply: don't confuse brazing refrigerant line theory with actual field conditions

The shortcoming of our discussion is that it ranges in Theory without having the benefit of the actual physical conditions involved.

That sort of exercise is useful for understanding underlying Theory but too often fails to notice determining factors in the field.

It's very common, for example, for a worker to fail to properly clean or breed a copper surface. The result would be an effort at breathing that makes a poor connection that may in fact be incomplete or later crack or break.

Those details are usually obvious only when you come across sectionally cut or disassemble the prior joint.

That leads me to infer that the leak could well be a failure to have properly made the joint in the first place. But I wouldn't assume that the only explanation is corrosion.

Here is some research on refrigerant leaks, but none of these sources address your question about the effect of brazing heat on refrigerant itself.

I suspect that a greater concern is the effect of brazing on the copper fittings, oxidation, flux combustion, debris, that can cause later HVAC malfunction if not properly-handled, or more basic, improper original joint construction and brazing.

See the refrigerant leak research citations given

at REFRIGERANT LEAK REPAIR

On 2018-08-17 by (mod) - no pressure on the high side means?

With no pressure on the high side I suspect that you're either essentially out of refrigerant or is it bad compressor

On 2018-08-17 by Narciso

I have a Lennox model#TGA150S2BH1G, serial# 5604K06732, reading 26hg on the suction line when in operation? compressor is working but no psig, added a few lbs of r22 still reading 26 hg when I close the valve? is my compressor bad ?

On 2018-05-03 by (mod) - why does the AC turn off after just one minute?

Ambrose,

Apologies but from just your one line text I can't diagnose your system. Any of several problems could turn off your AC compressor after a minute, such as

- the thermostat was satisfied

- the unit compressor is drawing excess current (failing motor) and tripped a circuit breaker

- a control board in the unit is defective

- there is a loose wire

- a safety device detected overpressure, possibly from another cause (a jammed TEV) and shut off the system

On 2018-05-03 by Ambrose

Ac compressor started on, and within by 1 min its went off. Whats the caused of that?

On 2017-06-20 by sonny

how do heat pump mechanics check heat pumps for leaks

On 2017-06-07 3 by (mod) -

Nhan

That sounds right as I'm guessing there are no isolation valves immediately on either side of the gauge.

On 2017-06-07 by Nhan

I have a leaking suction indicator gauge on my refrigeration system (fluid type gauge). It's running R22. It's plumbed up to the crankcase on my compressor.

I'm assuming I will need to pump it down and then close both service valves to replace gauge?

On 2016-07-30 by (mod) - P0 error code on heat pump?

Sorry Rohan but error codes are product-specific. You'll want to find the manufacturer/brand and model number of your equipment - found on the equipment covers and on its data tag.

With that information, if you don't have one, you will want to download the users' manual for your equipment as that will give you the meaning of error codes it may display.

On 2016-07-30 by Rohan

When I turn on my heat pump that showed a code P0 on the led window what is that mean?

On 2016-07-08 by (mod) -

Mario:

If I were working on my own unit I'd try that, with some careful surface cleaning first. But I would not warrant the repair for a customer beyond the time that my truck left the end of the driveway.

On 2016-07-08 by Mario

I found a leak in the joint between the body of the compressor and the plate that containd the elctric terminals, the leak is very tiny. I was planning to perform vacuum and add a little cyanoacrilate for high temperature, expecting the leak to be sealed. What do you think?

Question: recurrent leaks in low pressure side of AC

(July 3, 2011) james said:

My friend in Tucson,Az just lost her ac unit due to low pressure (leak) for the second time. I'm writing this on July 3rd 2011 and it is going to be 115F here today on a holiday weekend and trying to get service is almost impossible. I might ad that her neighbor is having their system charged every year by another company.

I've found that this seems to be the norm in this part of the country and is not specific to the AC industry. I would like to see these incompetent companies held accountable for their practices.

I can only imagine the frustration reliable companies must feel. Thank you for your time and work posting this information.
Best Reguards,jim

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Reply:

James:
about recurrent air conditioning refrigerant leaks:
it is very common for a tech to just add refrigerant and leave; it's a quick, profitable, recurrent service call.

Good practice is to find and fix the leak. Of course some home or business owners decide on the less costly service call and just keep adding refrigerant but the cost of repeated service calls says to me we ought to find and fix the leak.

Question: is $1700. to replace a coil and add refrigerant a ripoff n a 6 year old unit?

(July 19, 2011) Wilson said:

My A/C has been diagnosed with a coil leak and quoted $1694. to replace and add the 9 lbs of refrigerant. Sound reasonable or a rip off? The unit is only 6 y/o. Of course the 5 year warranty is gone.

Reply:

Wilson, replacing the coil involves more work than just a bolt-on repair: the system has to be emptied (and refrigerant saved for disposal), the old coil cut out, new coil soldered or brazed in place, a vacuum pulled on the system, tested for leaks, probably a drier installed, and then the system recharged;

I don't think that quote is weird, but certainly for any repair over $1000 it makes sense to get two estimates from two experts and to make sure that they are bidding on doing the same job so you can make an apples to apples comparison.

Question: $1300 to replace a coil and pan on my 2 year old Air Conditioner

(July 19, 2011) AC Coil leak and drain pan leak said:

I got an estimate today from Airtron in San Antonio $1298 to replace the coil/pan/ and a few other things for my Carrier A/C it's 2 years old and has 5yr warranty. Tehy came out and said i had a coil leak and drain pan leak my freon level was 75 and the norm is 125.

The $1298 i guess is for labor since the other parts should be covered by Carrier warranty. I may try to have someone who works there do it on the side for a smaller fee. It just seems so expensive to fix.

Reply:

Some reasons that an A/C coil leak/replacement and drain pan leak repair is costly (more than $1000) are listed in the Q&A above.

Question: can I re-solder a leaky air conditioner coil that has a tiny leak?

(July 22, 2012) Jim said:

I have a micro leak in the small diameter line from the outside compressor to the inside unit. the hole is at the junction of the tube to the connector, bad weld.

I want to try and re solder it but I don't know what would happen to all the freon in the pipes. I doubt that it is flammable but the molecules could break down to something bad. I still have sufficient freon so I don't want it to go to waste.

(July 22, 2012) Richard O'Hara said:

In looking for an a/c leak in a central a/c unit, why not first check for a loose wrench nut fitting? See if any of the nut connections are loose? You didn't even mention that.

Reply:

Richard your suggestion to try to fix a single leak in an AC coil makes sense - though there should be almost no wrench nut fittings except at the very ends of the refrigerant piping - all the rest are more often brazed.

YOu can often spot a leak at a threaded fitting because the leaking refrigerant gas also brings along a bit of lubricating oil that leaves the fitting dark and sticky.

The oily surface on the outside of the fitting around the leak also collects dirt and dust.

Watch out: you may have trouble soldering aluminum coil tubing or brazing and thus melting and destroying other thin-walled tubing materials.

You may contaminate the refrigerant system with debris that can then cause a cap tube or TEV vailure. If the leak is on the low pressure side perhaps an epoxy repair would work better.

Question: York heat pump keeps tripping the main breaker. Do I need a new unit?

(Mar 17, 2013) Diane said:

I have an 8 year old York heat pump system. It has been tripping the fuse and not producing air or heat for the past few days. I've been told it could be as simple as replacing a part if one canbe found or I will need to purchase a new unit. Thoughts?

Reply:

Diane,

The tripping breaker/fuse suggests an overcurrent that in turn may be due to a failed compressor motor (not at all trivial) or something less costly such as a bad contactor relay. This is a task for a trained service tech not a homeowner.

Don't make any expensive repair before the problem has been properly diagnosed.

Comment:

(Dec 9, 2015) a Houston appliance repair company

sam gordon said: very nice concepts.

Question: sulphur gases and refrigerant piping damage

(Apr 27, 2016) pankaj shah said:
why leaking is create often around area were sulferbase gas passes in the atmospher and what is the permanently solution

Reply:

Search InspectApedia.com for CHINESE DRYWALL to read about this sort of problem, causes & cures

Question: my ac gas is leaking

(June 3, 2016) Anonymous said:
my ac gas is leaking ,what is the easiest and best way to determine and fix it.

Reply:

Anonymous:
Please take a look at the article and links above on this page and let me know what questions remain, as that's my best organized answer to your question.

Question: AC tech says a refrigerant leak at a quick connect valve is not repairable

(June 8, 2016) Soph said:
A tech had told me my AC was not repairable due to fact that it was leaking at the quick connections. Why is this?

Reply:

Soph:

I can't fairly guess your AC tech by a mere e-text, but it sounds rather suspicious if not downright lazy.

The truth may be less irritating. Sometimes a tech will tell you "it can't be done" when of course it could be done, because she is making a judgment call that when you hear the cost you'll say that's not cost-reasonable.

But in the case of an AC system that is otherwise in good working condition and has a forward life, to condemn it because of a leak is rather odd.

Only if the leak were, for example, at the tubing brazed to the bottom of the compressor can might I think so negatively.

If the "quick connect" used a perforation method to make a connection to a refrigerant line and that perforation is leaking it would probably be necessary to cut ot that section and braze in a new one. It's a bit of work since it'd be good practice to also cut in a filter dryer on the same line after such repairs.

But "not repairable" sounds a bit extreme to me.

Question: nail perforated the refrigerant line

(June 23, 2016) Anonymous said:
Discovered a nail in the insulated line a year after the siding was done. Turned on the cooling no freon in system. Had short dist of pipe replaced should a gas and low filter be used after repair

Reply:

Anon:

I hate those nails through piping - at least it was refrigerant leaking out rather than water costing thousands of dollars in moldy wall and insulation repairs.

The use of a filter after repair is an interesting one in this case because the system is new. Still it'd be best-practice to install a filter or filters (in my OPINION) for a couple of reasons:

- the brazing of new line itself can place debris into the piping system

- the system sat empty for a year so there could be moisture in the system or other debris that never was caught

Even a small amount of crud, if it jams into the TEV, can foul up system operation.

Question: refrigerant charge in my car lasts only a few months

(July 4, 2016) Mike said:

My car air con leaks but lasts for two or three months, after which I hook up the bottle and rev until the vents chuck out air at 4c ( from 34c ambiant) Good to go for another couple of months.

My question is if the gas leaked out, how come there is negative pressure (I Dont have a vacuum pump) to suck the refrigerant back in, why isn't the system full of air?

Reply:

MIke:

There may be air contamination in your car AC system. But typically refrigerant remains in the system but at too-low a concentration to provide cooling. When the AC compressor runs that creates the suction to raw refrigerant back into the system from your charging can.

Often car AC systems leak around the compressor motor drive shaft - unlike building A/C compressor motors that are in a completely-sealed can and driven by electricity, the automotive AC compressor has to be driven by an external drive shaft, pulley, and motor fan belt.

The seal around that drive shaft often dries out and leaks during long periods of inactivity. For that reason in my vehicles I make a point of running the AC at least once a month regardless of weather, and when leaving a vehicle parked for a few months I make a point of running the AC for 15 minutes or so of driving before we leave the vehicle.

Question:

(July 4, 2016) Og said:
What is the causes of leakage in split unit air conditioning

Reply: Refrigerant leaks are caused by

Refrigerant leaks are caused by

- mechanical damage

- poorly-made connections, brazing errors

- vibration that wears a hole

- external corrosion at a cooling coil, condensing coil, or sometimes along the refrigerant piping itself

- internal corrosion in the system due to contaminants

- defective service valves

- something else I've not thought-of

See REFRIGERANT PIPING DAMAGE & LEAKS for details

Question: try using glue to seal a refrigerant leak?

(July 8, 2016) Mario said:

I found a leak in the joint between the body of the compressor and the plate that containd the elctric terminals, the leak is very tiny. I was planning to perform vacuum and add a little cyanoacrilate for high temperature, expecting the leak to be sealed. What do you think?

Reply:

xMario:

If I were working on my own unit I'd try that, with some careful surface cleaning first. But I would not warrant the repair for a customer beyond the time that my truck left the end of the driveway.

Question: meaning of heat pump error code P0

(July 30, 2016) Rohan said:
When I turn on my heat pump that showed a code P0 on the led window what is that mean?

Reply:

Sorry Rohan but error codes are product-specific. You'll want to find the manufacturer/brand and model number of your equipment - found on the equipment covers and on its data tag.

With that information, if you don't have one, you will want to download the users' manual for your equipment as that will give you the meaning of error codes it may display.

Try changing the filter.

If your air conditioning or heat pump system has lost its cooling capacity or won't start

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).

...

Continue reading at REFRIGERANT LEAK REPAIR or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• LOST COOLING CAPACITY
• REFRIGERANT GASES & PIPING - home
• REFRIGERANT CHARGING PROCEDURE
• REFRIGERANT LEAK DETECTION
• REFRIGERANT LEAK REPAIR
  • ACCURATE REFRIGERANT LEAK DIAGNOSIS
  • BUBBLES in the REFRIGERANT LINE SIGHT GLASS
  • ADD REFRIGERANT to "FIX" a LEAK?
  • REFRIGERANT LEAK SEALANT USE
  • DIAGNOSE NEED to REPLACE COOLING COIL
  • REFRIGERANT FILTER DRIER INSTALL AFTER REPAIR
  • REFRIGERANT RE-CHARGE AFTER REPAIR
• AIR CONDITIONING & HEAT PUMP SYSTEMS - home

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INDEX to RELATED ARTICLES: ARTICLE INDEX to AIR CONDITIONING & HEAT PUMPS

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