Question about Intertherm P3RA-048K Air Conditioner

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Out side unit will not go into defrost cycle

On cold mornings below 32degrees outside unit freezes on the outside coils. does not heat very well

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Most likely a bad temp sensor on the outdoor coil. you are seeing ice so its cold enough to defrost but the sensor is not seeing ice so it doesn't. usually a generic 3/8 or 1/2 clamp on sensor will fix. you can freeze the sensor with a little r22 and it should close and fall into defrost or jump it and it has to proof closed and the unit should defrost. if you jump it you may have to speed up the board to diagnose. usually jumping test pins together throws it into a 5 sec in 20 seconds out cycle. kind of like turning a 24 hour days into 24 seconds. or to protect the board you can just find the sensor pull it, replace it and watch what happens next cold night. good luck

Posted on Nov 10, 2008

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In middle of night, heat pump makes noise like something comes on and builds up then cuts off with a humming sound over and over again. Temp outside was only 43 degrees F.


The unit is defrosting. This is normal for heat pump systems, and they do it worst when the outdoor temperature is between just below freezing up to about 45 degrees F. The more humid it is outside, the more frost builds up, and the more the outdoor unit will defrost. Below about 25 degrees, most of the water is on the ground (not in the air), so the units will not have to defrost as often when it is that cold outside. If you are curious, you can monitor the unit on a cool, foggy day to see if it is actually building up frost, or if the unit is set wrong and defrosting on a false alarm. IF THE UNIT DOESN'T LOOK VISIBLY FROSTY, IT HAS BEEN SET TO DEFROST TOO OFTEN AND IS WASTING ENERGY! A TECH CALL TO REMEDY THE UNNECESSARY CYCLING WILL PAY FOR ITSELF QUICKLY!

While the outdoor unit is in this mode, it should be steaming and making a buzzing noise. This verifies the frost is being boiled off of the outdoor coil. 25355479-u40lsvyytnuesyuv3fbafhtd-5-0.jpg
Please mark my answer as useful.

Jan 05, 2015 | Air Conditioners

Tip

Why is Ice Forming on my Heat Pump


Many people have heat pumps and never realize that ice can form on the outdoor unit. Some have seen ice on their heat pumps but do not know how much is too much until they have a problem with not enough heat. Still others have a backup heat source and never know that they have a problem.

First off lets establish that heat pumps will form ice on the outdoor unit, usually whenever the outdoor temperatures go below about 40 degrees F. This threshold for ice depends a lot on the humidity of the air outside. If it is raining or snowing, the ice will form much more readily and rapidly. It is normal for ice to form on the outdoor unit because it is the cold side of the system when it is running in the heating mode. Because of this cooling, if the outdoor temperature is near or below freezing and there is moisture in the air, it will condense and freeze on the unit.

To keep the ice from building up to the point where it stops all the air flow, the outdoor unit will have a defrost timer board. This operates in conjunction with a sensor. Every 30 – 90 minutes the board will check the sensor. If the sensor tells the board that ice has formed on the coil it will then change the unit over from heating to cooling. This will make the outdoor unit the hot side for a short time to melt away the ice. While it does this, the unit will also energize the back up heat which is often an electric coil or a furnace. This will keep the inside air from blowing cold while the unit is defrosting.
When the sensor feels the coil temperature at about 50 degrees F it will then tell the board to return to the regular heating and switch the coils around again.

If this process fails to work for some reason the outdoor coil will become a big block of ice and look something like this.

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When your outdoor coil becomes totally frozen over it stops all the air flow through the coil and stops the heating process. In extreme case it can be very difficult and becomes a very long process to defrost the coil. You need to practice a lot of patience and care when defrosting a badly frozen coil. A torch or preferably a heat gun (hair dryer) can be used to speed up the defrost process. If it continues to occur the timer needs to be set to defrost more often or either the timer or the sensor has gone bad.

http://www.fixya.com/support/r3563896-air_conditioning__cleaning_the_condenser

http://www.fixya.com/support/r3636724-r_410a_new_refrigerant_air_conditioning

http://www.fixya.com/support/r3636751-air_conditioner_seer_seasonal_energy

on Jan 30, 2010 | Air Conditioners

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

The air conditioning fan outside the house is showing frost on the coils, what is the problem


Are you using your Air conditioner as a Heat Pump (Making heat in the house)- or as an Air Conditioner (making COLD air in the house.)

If as a heat pump, then remember-- that the WARM coil is now inside the house-- and the COLD one is outside-- So, if it is COLD outside, there is not enough HEAT out there, to keep the coil from going below freezing-- The unit may have to be turned off, and allowed to defrost, if you want more heat from the Heat Pump-

Let me know if this helped

Mack B

Jan 15, 2011 | Ruud Air Conditioners

1 Answer

My carrier heat pump has frosting on the outside on it's coils. I know that it's cold outside but is that normal?


Yes it is normal especially with high humidity. The moisture freezes on the coils just like on the evaporator coils in a freezer. The heat pump will defrost itself by shutting off the fan outside and reverse the flow of refrigerant to melt the ice when it build up then switch back to normal heat. That's why at times you may feel cold air coming out of the vents in the house. The outside coils are defrosting.

Dec 16, 2010 | Air Conditioners

1 Answer

Our air con runs, on heat, and after a time cuts out, blows cold and makes a sort of hissing noise (but not a real hiss) and then shuts down. It then restarts after a couple of minutes. Is this normal?


Yes.Think of a heat pump as a A/C in reverce in cool indoor coil is cold&outdoor coil is hot.Naw indoor coil is hot &outdoor coil is cold&fan is pulling in cold air from outside.its going to iceup& go into defrost cycle.If your unit has a timed defrost every 30,60,or90min.(witch ever yours is set for)Defrost control board checks a sensor on cond.coil,if it is frozen unit goes into defost.You will here a swishing noise,iis the reversing of refrigerant.you will also notice the outdoor fan is not operating&at termanation of defrost fan will blow out steem.the other metod is on demand defrost.when coil freezes unit defrosts.

Mar 02, 2010 | Air Conditioners

3 Answers

Goodman package- no heat below 30 degrees outside


I believe the unit you are describing is a heat pump. Heat pump are great when the temperature isn't below 30 With low ambient temps. outside it is much more efficient and comfortable to run aux. electric heat from the heat pump.

Jan 03, 2010 | Goodman PHKJ048-1 Air Conditioner

1 Answer

I have a heat pump and it freeze up


If you are referring to the outside unit freezing up, the issue is in the defrost cycle. The defrost cycle works something like this: The unit reverses the flow of freon causing the inside coil to blow cold air into the conditioned space and the outside coil is now working like an a/c unit, it gets warm to melt the frost/ice. The inside unit electric heat strips come on so you do not notice the cold air being blown in. The fan on the outside unit stops running to allow the coil to get good and warm.
Now the unit should go into the defrost cycle every 90 minutes or so. It should not terminate the cycle untill the coil is clear of frost. There is an "Klixon" type termostat that measures the temperature of the outside coil. This is most likely the problem. It is prematurely terminating the defrost cycle. I'd start there first.

Hope this helps, Let me know if I can be of any further help.

Dec 29, 2009 | Intertherm P3RC-030K Air Conditioner

1 Answer

My heat is freezing up because it is cold out side,what do I do


Sounds like you having a problem with the defrost board, also check to see if the freeze stat is connected, if not it will not since the coils temp and send a signal to the board to go in defrost and your electric heat strips should kick on if you have them. Depending on what unit you have you be able to which the dip switches to call for defrost at a quicker or longer time depending on the outside temp.

Jan 17, 2009 | Air Conditioners

1 Answer

Condenser frost's up on my heat pump


On a heat pump the system reverses during the heat cycle to bring in outside heat that will cause the outside coils to ice up. There is a defrost timer or pc board to send the unit into defrost every so often. This is a common problem with heat pumps or possibly low or refrigerant. Heat pumps will freeze up at low outside temps, but unless your in the Artic right now that shouldn't be a problem.

Sep 27, 2008 | Air Conditioners

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