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The a/c on heat mode will start indoor fan on start and outdoor compressor starts but the outdor fan does not run out door coil icing up

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Sounds like you are low on refrigerant or a refrigerant restriction somewhere...reversing valve or txv.

Posted on May 19, 2017

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Why does my sanyo model KHS2472 has a red light blinking in heat mode and a green in cooling mode, does not work in either mode makes a gurgling sound when it tries to run?


Hi,
The red light indicates it's either heating or in defrost mode
Check the outdoor unit if the compressor is running - the large pipe on the outdoor unit should be hot on heating or cool to touch on cooling
When in heating mode - the indoor fan will not start until the indoor coil is warm enough
If the reversing valve that changes from heating to cooling is faulty then you may encounter the same symptoms too
Probably need a Refrig Tech to have a look at it?
Good luck

Jan 07, 2016 | Sanyo 24KS72 Split System Air Conditioner

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

Is the heat pump cooling itself down? It is a combination heat pump/air conditioner wall unit.


If a unit is in heating mode the outdoor unit is in cooling mode (outside always does opposite of indoor) after a while if there is a build up of ice on outdoor coil unit stops and puts hot gas through outdoor coil to clear it. The indoor fan stops to avoid and heat loss in area served buy unit once this has been done and indoor unit coil is hot again fan will start. This is the correct operation of the unit to save against bust could and reduced efficiency

Dec 31, 2015 | Heating & Cooling

1 Answer

Front grill


Check the air filter and if it is dirty, replace..
Turn equipment off and let the ice melt.
After ice melts, place a/c in cooling mode and set the thermostat to 3 degrees below room temp display.

The indoor unit fan should start blowing cold air immediately and then turn off once the room temp drops one degree below the cooling temp setting.
If the indoor unit does cycle off, check the outdoor unit and make sure it turns off at the same time.
If the outdoor unit continues to run and the indoor fan is not running, the indoor unit will ice up.
A defective compressor relay that is stuck in a closed position will cause icing of the indoor unit because it keeps the compressor running when it should turn off with the indoor fan.

Do you have an error code being displayed on the controller?
Is there an led light that is flashing on the indoor unit?

Another possibility causing the indoor unit to ice up is if the freon in the system starts to get low.
Make sure the ice has all melted for this next check.
Pretty easy to check without special tools.
If the air filter is clean and there is no dust/ dirt blocking the fins on the indoor unit, turn a/c back on to cool and check that the indoor unit fan comes on and is blowing air good.
Once everything seems to running good go to the outdoor unit.
There will be two lines with black rubber insulation covering them.
Peel back the insulation three inches on each line and observe the copper lines.
If either line starts to frost up the a/c system is most likely low on refrigerant.


Another cause of indoor unit icing could be that the aluminum fins behind the air filter are clogged with dust or other foreign material.
This would block the air that must be pulled in causing the indoor unit coil to become too cold due to lack of air flow and it will ice up.

Operating the cooling system when the outdoor temperature is below 60 degrees can cause the indoor unit to ice up also.

I'm Robert.
Florida certified a/c contractor. 30 years experience.
Hope this helps.


Mar 18, 2014 | Fujitsu Heating & Cooling

2 Answers

I have a Mitsubishi heat pump that runs well but the outdoor unit does not defrost what could be the problem.


Why does my heat pump ice up in Winter?
Heat pumps naturally ice-up in the winter. It is normal for the entire coil to be covered in a white frost and even light ice, during cold weather conditions. However, it is bad for the entire unit to be encased in ice. This indicates ductless heat pump problems which should be addressed quickly to save energy and avoid serious damage to your ductless unit. These systems should periodically go into a defrost cycle. This keeps the unit running efficiently. If the coils are blocked by ice, proper heat transfer between the coil and the outside air will not occur.
How does the defrost mode work?
When the mini split heat pump goes into defrost, the reversing valve inside of the outdoor unit is energized, switching the system from heat to the air conditioning mode. The outdoor coil becomes the hot, the indoor coil becomes cold, and both - the outdoor and indoor fans shut off. This allows the outdoor coil to melt accumulated ice. When the built-in micro-computer analyzes that all ice have been melted, the heat pump heating system goes back to heating mode.
sanyo-mini-split-defrost.pngA cloud of water vapor may be seen rising over the outdoor unit and a "whoosh" sound can be heard as the refrigerant reverses direction. The entire process usually takes up to 10 minutes (depending on conditions).
How often does the system goes into defrost mode?
Ductless mini-split heat pumps have different ways of determining when to go into defrost. The built-in microcomputer determines outdoor temperature, refrigerant pressures, and several other factors. In colder temperatures the system will go into defrost more often than in warmer.
If a ductless mini split heat pump is severely iced-up in the winter it is possible that it isn't defrosting (though there could be many other causes). Let the manufacturer certified technician check your system

Oct 29, 2011 | Mitsubishi Mr. Slim MXZ30TN Air...

1 Answer

I have a goodman self contained heat pump that is 3 and 1/2 years old. I wake in the night to hear what sounds like the fan runnning and running and running and air moving thru the vents. Then I will hear...


Heat pumps are a very efficient design when working properly. But lose efficiency the colder it gets outdoors. I usually tell people when it drops below freezing to turn the thermostat to aux or em. heat. A heat pump can remove heat from 20°f air. But not very well. More heat at 30°f air, obviously, and so on. So the colder it is outdoors, the longer it will operate to remove heat from outdoors. And then, if it can't keep up, it brings on the electric heat elements to compensate. Now you are running both outdoor and indoor heat. This is where it's inefficient and costly. Also, the outdoor will start to freeze up. This is normal unless you can see a substantial amount of ice. The heat pump will engage defrost mode, cycling on the electric heat indoors. And defrost mode is actually cooling mode! The reversing valve in the heat pump switches to cooling mode, cycles off the outdoor fan, and defrosts for a set time or temp. So now your electric heat is engaged, and your indoor coil is a COLD coil! Not hot! Very inefficient. These 2 things are why your elec bill is higher in the winter. So it makes sense to me, if the elec heat is going to be on anyway, to move the tstat to aux or em. heat, when it's going to be below freezing outdoors. This will turn off the heat pump and use elected heat only. The only down side to this is, if you don't have enough elec heat to keep you warm, you may need both heat pump and elec heat. So trial end error until you find what works. Also, have a qualified tech check the system for operation and efficiency. Hope this helps!

Apr 08, 2017 | Goodman PHKJ048-1 Air Conditioner

1 Answer

Indoor fan slow to rotate in heat mode and no heat/compressor


The indoor fan will not run at normal fan speed untill the indoor coil reaches 32oC. This is done so that a cold draught is not felt when outdoor unit is not running. Check to make sure the outdoor unit is operating. If the outdoor fan is running but there is no indoor fan after 5 mins then you must likely have a gas issue or a fault compressor circuit.

May 31, 2010 | Fujitsu 24R1 Air Conditioner

1 Answer

Indoor unit freezing up


THE OUTDOOR UNIT HAS A CONTACTOR WITH THE CONTACTS WELDED TOGETHER THE CONTACTOR CONNECTS TO THE COMPRESSOR AS IT TYPICALLY PULLS A SURGE OF 20 -30 AMPS OR MORE..WITH THE INDOOR UNIT IN FAN ONLY THE COMPRESSOR SHOULD NOT BE RUNNING. THE CONTROL WIRES GOING TO THE UNIT HAVE 24 VOLTS TO THE CONTACTOR TO PULL IN THE CONTACTS TO SUPPLY 220 TO COMPRESSOR.

Mar 09, 2010 | Heating & Cooling

3 Answers

Split unit, I get heat but no cold


I have run into this with the LG brand systems. try shutting power off to the outdoor unit to reset all units. If problem persists, it could have to do with a charge level of refrigerant (freon) or possibly a failed control board.

May 16, 2009 | Fujitsu 24R1 Air Conditioner

2 Answers

Soleus KFR-18 Air Conditioner Problem


Check your thermostat settings at heat mode.

Jan 03, 2008 | Soleus KFR-18 Air Conditioner

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