# How do I know my house AC freon is low?



## JJboy (Oct 12, 2010)

You just need to read the gauges......easy like that........LOL


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## gregzoll (Dec 25, 2006)

First thing is, what temp are you setting the thermostat at. Also, when was the outside unit & A-Coil on the inside unit last cleaned. Also, make sure drapes are closed in all rooms, outlets & switches, doors & windows do not allow air leaks, your attic access has foam weather stripping around the edge where the access panel closes, to not allow heat to enter the home. Also, what is the temp of the are at the nearest register & farthest register on the furnace/air handler.


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## beenthere (Oct 11, 2008)

Reading the gauges is easy. know what the readings mean is a different story. there is no one set of readings that means good.


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## Dwillems (Jul 14, 2011)

PPang100 said:


> I know we are going through a heat wave, but I need to know why my AC is not keeping up with cooling sufficiently. My themostat appears to be about 3, 4, 5 degrees higher than the set temperature. One possibility is low in freon. I want to know how to read the gauges that the service man would hook up to the compressor. I can keep the service man honest if I knew how to read the gauges. Can someone help please? Thanks.


I had this problem recently and I haven't learned how to read gauges yet but there's another indication of your freon being low, or why your AC isn't cooling sufficiently. Check the evaporator coil that's installed in your ducting. It looks like a radiator with all the fins. Mine was freezing over. A few causes of this is first blocked fins, I cleaned it out gently with an air compressor and vacuum. Second is a blower that's running out of oompf which isn't that likely but I cleaned my blower fins from the 20 years of buildup. Third is low freon. It doesn't flow through the pipes well and ends up freezing the coils over. You can get an idea if this is happening if your condensation drain isn't draining, or if you hear a gurgling sound in this area (there shouldn't be any sounds coming from this part of the AC system). My return line coming from the coil was even freezing over outside of the ducting. 

Once you figure this problem out it's a good idea to go through your attic or crawlspace/basement and looking at the ducts that are visible. Ensure they aren't kinked anywhere, and take some metal tape (we call it speed tape in the military) and seal all of your joints in the ductwork. Also don't close off too many vents throughout the house or there won't be enough airflow going through the ducts. In order to keep that coil from freezing, sufficient airflow has to keep running over it to take the coldness away. Another common problem is a blocked return duct, ensure there's no furniture within a few feet of the return duct/vent opening or the system can't draw enough air in to pump through your house. Also keep objects away from the Unit outside, keep it clean (a good spray with the garden hose works fine), and use pipe insulation over the supply line going from your ac unit outside all the way to your evaporator inside.


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## COLDIRON (Mar 15, 2009)

If the unit has been doing the job all summer and now it's not keeping up maybe you should clean the coils outside, change the filter, close all drapes previously mentioned, and give the unit plenty of time . In this weather it will probably run mostly all day, we are at or close to design conditions so the least little thing not maintained will show up right now.


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## tech95 (Jul 21, 2011)

COLDIRON said:


> If the unit has been doing the job all summer and now it's not keeping up maybe you should clean the coils outside, change the filter, close all drapes previously mentioned, and give the unit plenty of time . In this weather it will probably run mostly all day, we are at or close to design conditions so the least little thing not maintained will show up right now.



This is sound advice. Also if it is 100+ in your area right now, it is possible that the unit may be running outside of it designed sizing conditions, the area I live in for example typically uses 95 as a design outdoor temp for sizing, and I have responded to many calls where this is the case. But, you definately want the outdoor coil, as clean as possible. I have been a tech for 12 years now and I can assure you my personal unit is very well maintained but did fall almost 2 degrees behind set point a few days ago when it was 104. So shut all power off to the condensing unit (outdoor unit) and clean the coil from the inside, forcing water outward. If at any point you begin to question what should be taken apart, or what not to touch, it would probably be worth calling a qualified technician.


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## PPang100 (Jul 21, 2011)

Thanks for the response. If no set reading can mean goof, then how does one tell if the freon is low?


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## PPang100 (Jul 21, 2011)

gregzoll said:


> First thing is, what temp are you setting the thermostat at. Also, when was the outside unit & A-Coil on the inside unit last cleaned. Also, make sure drapes are closed in all rooms, outlets & switches, doors & windows do not allow air leaks, your attic access has foam weather stripping around the edge where the access panel closes, to not allow heat to enter the home. Also, what is the temp of the are at the nearest register & farthest register on the furnace/air handler.



Excuse my lack on knowledge on home AC, but what is an A-coil?


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## PPang100 (Jul 21, 2011)

Dwillems said:


> I had this problem recently and I haven't learned how to read gauges yet but there's another indication of your freon being low, or why your AC isn't cooling sufficiently. Check the evaporator coil that's installed in your ducting. It looks like a radiator with all the fins. Mine was freezing over. A few causes of this is first blocked fins, I cleaned it out gently with an air compressor and vacuum. Second is a blower that's running out of oompf which isn't that likely but I cleaned my blower fins from the 20 years of buildup. Third is low freon. It doesn't flow through the pipes well and ends up freezing the coils over. You can get an idea if this is happening if your condensation drain isn't draining, or if you hear a gurgling sound in this area (there shouldn't be any sounds coming from this part of the AC system). My return line coming from the coil was even freezing over outside of the ducting.
> 
> Once you figure this problem out it's a good idea to go through your attic or crawlspace/basement and looking at the ducts that are visible. Ensure they aren't kinked anywhere, and take some metal tape (we call it speed tape in the military) and seal all of your joints in the ductwork. Also don't close off too many vents throughout the house or there won't be enough airflow going through the ducts. In order to keep that coil from freezing, sufficient airflow has to keep running over it to take the coldness away. Another common problem is a blocked return duct, ensure there's no furniture within a few feet of the return duct/vent opening or the system can't draw enough air in to pump through your house. Also keep objects away from the Unit outside, keep it clean (a good spray with the garden hose works fine), and use pipe insulation over the supply line going from your ac unit outside all the way to your evaporator inside.


Thank you for being so helpful. I will save your mail for later use.


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## PPang100 (Jul 21, 2011)

COLDIRON said:


> If the unit has been doing the job all summer and now it's not keeping up maybe you should clean the coils outside, change the filter, close all drapes previously mentioned, and give the unit plenty of time . In this weather it will probably run mostly all day, we are at or close to design conditions so the least little thing not maintained will show up right now.


Your advice is useful. I saved it for later reference. Thank you very much


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## beenthere (Oct 11, 2008)

Whats called super heat and sub cooling tells weather a system is low has a restriction or dirty coils.


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## PPang100 (Jul 21, 2011)

Dirty coil seems like a very common problem with AC not cooling properly. Thanks.


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## Mrdippy (Jan 25, 2011)

I had a day this week where my AC ran full tilt but could not get the temp of the home under 77. The air out of the vents was a very cool temp the whole time - the outside environment I think was beyond the abilities of my home's insulation and the outside temp. Calling a tech to check your refrigerant is the only real way to know if you are lacking and preferably when the temp outside is 70+. I have, but since my AC is working relatively AOK I am low priority for them to get here to check the refrigerant levels.


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## Dwillems (Jul 14, 2011)

PPang100 said:


> Excuse my lack on knowledge on home AC, but what is an A-coil?


Its the condensor coil inside the ducts that transfers the cold to the air and heat to the refridgerant... Most of them are in the shape of an A to maximize surface area while still fitting in the ductwork


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## G-Mo (Feb 16, 2009)

Dwillems said:


> Its the condensor coil inside the ducts that transfers the cold to the air and heat to the refridgerant... Most of them are in the shape of an A to maximize surface area while still fitting in the ductwork


Most people call this an evaporator coil.


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## COLDIRON (Mar 15, 2009)

What do most people say when their A/C is not working properly?

I think I need freon.

Truth be told most units don't need freon , most of the time it is an electrical problem. It's just one of those things people have always said it probably started years ago with unscrupulous air conditioning mechanics / freon jockeys that made money telling people their unit was low on freon and they need to fill it.

Note; freon does not wear out or need to be changed unless there is a leak or something happened internal to the system.


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## Technow (Nov 12, 2010)

COLDIRON said:


> What do most people say when their A/C is not working properly?
> 
> I think I need freon.
> 
> ...


What I have been running into lately is lack of maintenance contributing to the electrical problem. dirty condensers, unchanged filters, dirty evaps on the days where you need 100% capacity


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## yuri (Nov 29, 2008)

Years ago we had a LOT more freon leaks, at least where I am. We had those self piercing DIY aereoquip fittings on the precharged lines sets the Cdn built Keeprite units used and later Heils. Carrier had those tapered ferules/comp fittings that leaked. Ground shifting caused lots of those to leak. Lennox had leaky plastic service valves caps and no packing on the stem etc etc. Passing gas :nuke: /topping up every year was a common occurrence and people got used to it. New units are all welded or proper flare fittings that don't usually leak.

Maintenance, what the heck for? Out of sight and out of mind the unit is.:thumbsup:


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