A/C or Heat Pump Refrigerant Problems
Basic approach to fixing an A/C or Heat Pump refrigerant problems: leaks, wrong charge, overcharging, undercharged
REFRIGERANT PROBLEM TYPES - CONTENTS: Basic HVACR refrigerant problem diagnosis & repair procedures. HVAC equipment does not "consume" refrigerant. You should not normally have to add or replace refrigerant gas. If the charge is too low or high surprising things happen and costly damage an ensue.
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Air conditioner or heat pump refrigerant problem diagnosis & repair procedures: types of HVAC refrigerant problems.
Here 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
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 this 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.
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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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?
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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Timothy Hemm, Yucala, CA, contributed photographs of electrical wiring and equipment installed in California buildings. Mr. Hemm can be contacted at TimHemm@yahoo.com
A/C - HEAT PUMP CONTROLS & SWITCHES: air conditioner controls and switches - begin here if your A/C won't start. Here's an important tip: most refrigeration problems, in air conditioners, refrigerators, or freezers, are electrical, not mechanical. In air conditioning school, we used to drive out and collect abandoned refrigerators that people were tossing out during our community's spring cleanup week. Taking these appliances back into the shop we found that almost always the problem that had caused the owner to dispose of their air conditioner or freezer was in an electrical connection or electrical control. So it's worth checking out switches and controls on an air conditioner before replacing more costly components.
OPERATING DEFECTS: major air conditioning problem symptoms and how to get the air conditioning system working again,e.g. compressor or fan noises, failure to start, and inadequate cool air volume
A/C DIAGNOSTIC FAQs: air conditioning system diagnostic FAQs: Q&A about air conditioner repair - a detailed air conditioning system diagnostic checklist
Thanks to reader and research scientist Cyril Roberts, Barbados, for technical discussion and investigation of air conditioning system dehumidification problems (April 2009).
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]
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
"Air Conditioning & Refrigeration I & II", BOCES Education, Warren Hilliard (instructor), Poughkeepsie, New York, May - July 1982, [classroom notes from air conditioning and refrigeration maintenance and repair course attended by the website author]
Fiberglass: Indoor Air Quality Investigations: Fiberglass in Indoor Air, HVAC ducts, and Building Insulation
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