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American Standard Heat/ac system

The last 2 months our system has frozen up. We change the filter every 30 days. When it freezes up we turn off the unit, hose down the evaporator wait 30 mins. Crank it up and it works Compressor new 2 months old.

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It has been suggested to us we change out the thermostat.Good idea considering if the ifs its reading colder than actually appears on readout the unit will freeze up. The unit is working right at this moment, but, when we change thermostats we will let you know the outcome.

Posted on Aug 03, 2008

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American Standard heat pump troubleshooting


If the compressor is not frozen, then it is most likely one of the starting capacitors on either the compressor or the fan motor. These can fail without warning and without any outward indication. They are shaped like small cans or oblong cans and have 2 or more wires that attach to them with terminals. If you are going to remove one or check them, Make sure the power is off first.

Aug 11, 2014 | American Standard 282999 4" Heat Pump Snow...

Tip

Why your unit is freezing up.


To understand why your AC or heat pump is freezing up, it helps to know how your system works.

There are 7 major parts to an AC system, 9 with a heat pump.

1 - Condenser/heat pump (The outdoor unit)
2 - Air Handler (the indoor unit unless the system is a package unit, then all is outside in one system. The air handler is usually found under the home, in an attic, or in a closet.)

In the condenser are the following major parts.

3 - Compressor
4 - Condenser coil
5 - Condenser fan
6 - (HPs only) reversing valve

In the air handler are the following major parts.

7 - Blower motor
8 - Evaporator coil
9 - (HPs only) electric heat strips

Some systems known as "dual fuel systems" use another heat source in place of the heat strips, usually a gas furnace. I will address gas furnaces in another post.

When an air conditioner is operating properly several things are taking place.

1 - The compressor is compressing or "pumping" refrigerant through the system.

2 - through changes in pressure, the refrigerant makes the evaporator coil get very cold, and the condenser coil gets very hot.

3 - The blower motor/fan circulates air across the evaporator coils, as the room temperature air (Also known as "indoor ambient") goes through the cold coil, it exits, cooled approximately 15 to 20 degrees cooler than when it entered. (In a ducted system, the blower is also the fan that circulates the air throughout the home.)

4 - The condenser fan circulates air across the condenser coils. As the outdoor air goes through the condenser coil, it removes heat from the coils that are very hot. This in turn removes heat from the refrigerant so it can run its cycle again, and through pressure changes, cool the evap coil.

5 - With a heat pump, the reversing valve reverses the flow of refrigerant in the condenser and evaporator coils.
In AC mode, the evaporator coils get cold, and the condenser coils get hot. But in heat mode, the evaporator gets very hot, and the condenser very cold.

Now, whichever coil is getting cold will freeze up if there is inadequate air flow across the coil, as the refrigerant in it is far below freezing, and there is not enough airflow to keep the humidity in the air from freezing on the coil.

Things that can cause poor airflow are,

1 - Dirty/clogged coils
2 - dirty/clogged filter (will only effect evaporator coil)
3 - Closed/blocked vents (will only effect evaporator coil)
4 - Malfunctioning or dirty fan

Low refrigerant will also cause a coil to freeze up, reduce efficiency and cause the system to run for long periods of time. Not to mention, shortening the life of the unit.

With a heat pump, in heat mode only, the condenser (outdoor) coil will routinely begin to freeze up in cold temperatures. This is due to the fact that the refrigerant is below freezing, and the cold outdoor ambient temp is not warm enough to keep the condensation in the air from freezing on the coil.

Note, a properly working AC should never freeze up.

A heat pump is equipped with defrost controls to prevent ice buildup.
Some are controlled by timers, some by temp.

When a HP is going into defrost mode, the condenser fan shuts down, the reversing valve reverses the flow of refrigerant and the once cold condenser coil now gets very hot, defrosting the coil. (Many people have said this process sounds like the unit is coming apart, or about to explode and are frightened by the "smoke" which is really just steam from melting ice that comes off the unit.)

During defrost mode, the secondary or "auxiliary" heat comes on to ensure that you are still getting warm air from the vents. (Again, this can be electric heat strips or a dual fuel system)

If you are experiencing cold air from the vents during defrost, that means your auxiliary heat is malfunctioning.

The auxiliary heat is used for three purposes.

1 - during defrost mode to maintain warm airflow (automatic)
2 - when the HP cannot maintain the set temp due to extreme outdoor temps. It comes on when the indoor temp drops several degrees below the set temp on the thermostat (automatic)
3 - For emergency heat source when the HP is not working. (Manual)

To recap....

Iced up coils?

Poor airflow
low refrigerant
Malfunctioning fan
failing defrost system


There are two things that can be done in a pinch to help de-ice frozen coils. This may get you by until the repairman can get there, or you can fix the system if you are a do-it-yourselfer.

HPs frozen outdoor coil in heat mode, not going into defrost?

Cover most of the vents, and turn the system onto cooling mode until the outdoor coil is thawed. then uncover vents and return to heat, or emergency heat. (this usually takes 15 min or less)

Frozen coils in AC mode with a heat pump?
Turn the system to heat with the thermostat on just high enough to get the system to come on. (again, usually takes 15 min or less to thaw.)

AC only, with frozen evap coils? (this can sometimes be seen frozen all the way outside to the compressor on the copper lines.)

Turn the system off, and the fan switch from "auto" to on".
This will usually defrost the coils within 1 to 2 hours.
(If your system has the furnace in line before the evap coil, turn the system to heat, and the furnace will defrost the coil within minutes.)



on Dec 25, 2008 | Carrier XHB123D X/Y Series Heat/Cool Air...

1 Answer

Why does ac go to 80 degrees when set at 76


Sounds like you need another opinion from another AC man. If you are in an apartment complex, it has been my experience most apartment techs have limited knowledge of what to check. Try this
1. With the unit on, go to you air filter and check for proper air flow. If you are using pleated filters, stop. Use what is called 30 day throwaway filters. Pleated filters block 35 % of the air flow and can cause evaporators to freeze over. Ace hardware still stocks the ones with the blue mesh with cardboard edges. I have used the same filters for over 2 years. All I do is use my vacuum cleaner and clean the dust bunnies collected every 30 days.
2. Perform an sight inspection of your duct system. I have had several customers whose duct have fallen off and they were air conditioning the attic space and/or crawl space.
3. Have your AC man determine your superheat and subcooling value for your airconditioning unit. If your AC man does not know what these are then he really isn't an AC man. A typical value for most superheat (SH) and subcool (SC) is 12 to 15 degrees. These values are typically normal values but can change due to design criteria established among manufactures. If your AC man does not know what these are or can not measure these you need to get someone that know how to obtain them. These values are typical value for a normally charged equipment and does not vary from refrigerant to refrigerant.
Hope this helps.

Jun 26, 2014 | Goodman Air Conditioners

1 Answer

Water leak in condensing furnace


Several problems can be associated with this problem

If running heat it is likely a drain hose or Drain connection that is plugged up. Simply blowing these lines out can solve your problem.

If running AC it is likely a Drain from the coil to the Drain line that is plugged up, or you have frozen the unit up. Check the unit outside, if the big copper line or compressor is frozen, turn system off immediately and call a service company to check the system out.

I also recommend changing your air filter every 3 months if you haven't done so.

Mar 06, 2014 | American Standard Air Conditioners

1 Answer

The heat pump stays on to 20 deg (outdoors) and the burners will not work till the temp is under that leaving the house at a max 65 deg, I beleave the heat pump should true off around 30 -35 deg ? then the...


Remove the cover of the circuit board and controls on the outside unit. Some units have a thermostat that allows you to set the temperature at which it switches to the second stage of heat. Set that for about 34 degrees.

Jan 02, 2011 | Air Conditioners

2 Answers

Why does my AC keep freezing (Carrier FB4ANF036). I have replaced the blower motor less than a month ago due to the same problem. Just last night we had a lightening storm and shortly after that the AC...


if your system is a heat pump you can switch to heat and see if coil outside gets cold while indoor blows warm air - then switch back to a/c - both coils should not be cold at the same time - low freon pressure / dirty coil / dirty filter / low air flow causes freezing

Sep 22, 2009 | Carrier Air Conditioners

1 Answer

Honeywell T8112 Air Conditioner Will Not Cool, But Blower Works


make sure the system switch is in the cool position, then press run program button and allow a couple of minutes for system to cycle on, if it doesn't come on press the button for lowering the set point, set it to 72 degrees and then press the hold temperature key.

May 27, 2009 | Honeywell ER150B Air Conditioner

1 Answer

Wall ac unit keeps freezing up inside.


Do not run it on maximum cool and fan on low. Freezes up all the time this way.

May 01, 2009 | Air Conditioners

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