Air conditioner or heat pump refrigerant problem diagnosis & repair procedures: types of HVAC refrigerant problems.

In addition to giving an index to our air conditioning or heat pump refrigerant problem diagnosis and repair articles, we explain what happens if the refrigerant charge in an A/C or heat pump system is leaking, under-charged, over-charged, or if the technician used the wrong type of refrigerant.

Understanding what's wrong with the refrigerant in the system can explain temperatures that are too low, too high, or it may explain refrigerant line and cooling / evaporator coil icing - too-cold, too-warm or too-weak air flow in the system.

This article forms part of our series on how to diagnose an air conditioner or heat pump that is not cooling: this article explains how to diagnose and correct air conditioning problems like lost or reduced air conditioner cooling capacity, reduced or no cool air flow, reduced or no actual lowering of the air temperature, or an air conditioner that won't start.

Air Conditioner Refrigerant Problems - Refrigerant Leaks, Low Refrigerant, Wrong Temperatures

Refrigerant problems: Improper air conditioner refrigerant charge - too little, too much, too leaky:

An air conditioner system which has lost some (but not most) of its refrigerant will sometimes run too cold at the evaporator coil, leading to coil icing and loss of cool air delivery in the home.

If the filters are clean and the coil ices-up th,is condition may be present. A service technician will need to evaluate and test the system and if needed, adjust the refrigerant charge.

• Low refrigerant level in the air conditioning system:
  
  Watch out for refrigerant leaks that lead to a repeat of this problem. An air conditioner or refrigerator is a sealed system that should not normally "use up" refrigerant.
  
  If the cooling system is low on refrigerant because it has a leak, it is much smarter to find and fix the leak than to simply keep adding refrigerant. If you keep adding refrigerant to a cooling system you're leaking possible contaminants into the environment as well as wasting money.
  
  Abnormally low output air temperature:
  
  A refrigerant leak in an air conditioning system may show up first as abnormally low system output air temperature, followed by rising air temperatures, followed by just plain old warm air coming out of the system, as the amount of refrigerant that has been lost increases.
• Loss of most refrigerant
  
  from an air conditioning system means that the cooling coil will not get cool at all.
  
  Abnormally high output air temperature: A service technician will need to evaluate and test the system and if needed, find and fix the refrigerant leak, evacuate the system, and install the proper refrigerant charge.
  
  Don't keep adding refrigerant. Refrigerant leaks should be found and repaired. It may be easier to keep adding refrigerant, and sometimes a refrigerant leak can be hard to find, and of course it's convenient and profitable for the HVAC repair company to keep delivering refrigerant,
  
  but the proper repair for low refrigerant is to find an fix the refrigerant leak, not to just keep adding refrigerant.
  
  See A/C REFRIGERANT LEAK DETECTION for details.
• Improper refrigerant charge - overcharging: too much refrigerant
  
  can also lead to improper air conditioning system operation and in some cases can damage the compressor (called liquid-slugging the air conditioner compressor).
  
  A service technician will need to evaluate and test the system and if needed, adjust the refrigerant charge. In this case the cooling coil is probably not going to ice-over, it just won't get cool.

 

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Tech said our system had no refrigerant but he couldn't find a leak

Our brand new air conditioner installed October 2018 never cooled when system was turned on 3 weeks ago and our home was vacant..

Technician said there was no refrigerant at all and he could find no leaks.

He filled it with refrigerant.

What could have caused this if no leaks could be found.

Will the fact that it was running for weeks without refrigerant cause damage to the system. - On 2019-06-15 by Anonymous -

Reply by (mod) - no refrigerant but system ran: damage?

Nevertheless if there was no refrigerant in the system then without a doubt, there was a leak.

It could have been a leak anywhere in the system or even a valve that was dirty in the valve seat or otherwise left open.

Yes, unfortunately, running an HVAC compressor for weeks without refrigerant may (possibly, not definitely) have damaged it or shortened its life.

Why? Because normally there is a lubricant included in the refrigerant mix that lubricates the moving parts in the compressor motor.

A/C service company says leak in new system: lines need replacement

Just finished purchasing a new unit, I being experiencing problems with the unit leaking and not cooling.

The company says I have a leak in the lines, they checked condenser and evaporator and the problem they say is on the lines.

And that they need to replace lines. My question is could this be possible . - On 2018-09-20 by Albert

Reply by (mod) - find and fix the leak; replacement is sometimes cheaper than troubleshooting

Albert:

what leak? condensate or refrigerant?

If I assume you mean refrigerant, the lines could be damaged or leaking somewhere but most often the leak is at a connection.

Leaks occur at the cooling coil too but not so likely with a brand new unit.

Usually one can spot leaks by using a leak detector.

The repair could be re-brazing/soldering a connector such as at a filter-drier, but the company may think it's faster and will be less costly to simply replace a refrigerant line than to try to find the leak point.

Just adding refrigerant to the unit is not a real solution.

Just adding refrigerant to the unit is not a real solution. It might feel right, but it isn’t. The amount of refrigerant in the unit must be very precise and exactly match the manufacturer’s specification. Understand that an undercharged installation is rare, and if your AC unit s low on refrigerant, a leak is most likely the problem and needs to be fixed immediately. You need to figure out why your AC is leaking and what you can do to fix it. - On 2018-08-01 by Alex Stanford - J

Reply by Mod

Thanks Alex,

We don't recommend that any homeowner try to add refrigerant themselves: there is virtually no chance that it will be done correctly and the risks add to the above that of damaging the equipment.

We agree completely that simply adding refrigerant without finding and fixing the refrigerant leak not only wastes money, it continues to contaminate the environment by releasing refrigerant to the atmosphere.

However I've also been disappointed to find that some techs scrimp on the re-charge, basing it only on temperature measurements and not on adding enough refrigerant to reach the full refrigerant charge quantity specified by the manufacturer. The result is an expensive service call that leaves the consumer feeling short-changed.

On 2016-09-26 by Julian Heat Pump doesn't cool but heat works in winter - coolant leak

I have a heat pump and the ac does not cool will the heat still work this winter. There appears to be a coolant leak. The fan works fine

Reply by (mod) - you're running on backup heat - more expensive

Julian:

If the A/C doesn't cool then the heat pump won't heat either.

A heat pump in heating mode is simply running its refrigerant in the opposite direction, moving heat in the opposite direction.

So when the heat pump is in HEAT mode and isn't producing heat, your system will either automagically or manually switch into BACKUP HEAT mode. That'll probably run electric heating elements in your air handler and give you heat, but at a higher cost.

What might cause very high pressure on both HI and LO sides?

Did a startup. on Thursday Friday unit was making loud noise and showing 240 psi on both high and low side,what could cause this in less than 24hrs - On 2016-04-02 by Shaunoffshoreair@Gmail.com -

Reply by (mod) -

stuck TEV ?

Is Air Conditioning refrigerant a liquid or a gas?

is an air conditioning refrigerant liquid or a gas? are there any concerns with a leakage of a window ac unit? - On 2016-03-16 by james

Reply by (mod) - It's both, depending on where you look

James: depending on where the refrigerant is in the system it is a liquid OR a gas. The refrigerant changes state - or has its state changed by the compressor and the condensing coil from a gas to a liquid and in the evaporator coil where cooling takes place the refrigerant changes from a liquid to a gas.

Refrigerant systems in good working order are sealed systems, there is not refrigerant leakage. If refrigerant is leaking, say from corrosion or mechanical damage to refrigerant tubing or to one of the system coils, the system needs to be repaired: and you'll know it because the system will stop cooling.

Question: ok to use automotive freon re-charge canisters to top off low refrigerant in a heat pump?

(May 9, 2015) Blaine said:
my heat pump is low on Freon...can I use a can of auto ac Freon to boost it up?

Reply: NO

Blain:

No you should not use auto refrigerant to try to re-charge a leaky central air conditioning or heat pump system.

The proper repair is to first find and fix the leak.

Trying to adjust the charge as you describe is improper, cannot provide the proper charge quantity as you don't know what's needed nor how much you've inserted, may use the wrong refrigerant type, and further risks introducing air or other contaminants into the system, and is not something you suggest.

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

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Suggested citation for this web page

REFRIGERANT PROBLEM TYPES at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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

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