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Photograph of client using tissue to look for air conditioning air flowRepair A/C or Heat Pump Refrigerant Problems

Basic approach to A/C or Heat Pump refrigerant problems:
leaks, wrong charge, overcharging, undercharged

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.

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

Air conditioning refrigerant gauge set (C) Daniel Friedman

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.

 

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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

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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Citations & References

In addition to any citations in the article above, a full list is available on request.

  • Timothy Hemm, Yucala, CA, contributed photographs of electrical wiring and equipment installed in California buildings. Mr. Hemm can be contacted at TimHemm@yahoo.com
  • Thanks to readers Beth & Dennis for asking about how to improve an inadequate air conditioning system supplying cool air through crawl space ducts and floor registers. (May 2010).
  • Thanks to reader William Smith for discussing cooling coil leaks and lost cooling capacity diagnosis - June 2010
  • Thanks to reader Jacob Behrends, FL for discussing how a clogged condensate drain line can overflow condensate into a condensate pan that in turn may contain a safety switch that shuts down the whole air conditioning system. August 2010.
  • Determining Electric Motor Load and Efficiency, U.S. Department of Energy, web search 08/01/2011, original source: http://www.p2pays.org/ref/40/39569.pdf [copy on file at InspectAPedia.com]
  • In addition to citations & references found in this article, see the research citations given at the end of the related articles found at our suggested

    CONTINUE READING or RECOMMENDED ARTICLES.


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