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I have 2.5TON heat pump that works fine in ac mode but does not heat only have heat in emergency .condenser fan does come on when heat is selected

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The heat pump is either wired wrong on the low voltage side or the reversing valve is sticking. these need checked by a tech. if you are showing emergency heat then your thermostat is meant for a heat pump and that is also a good place for the tech to look to make sure it was wired properly from the start

Posted on Dec 15, 2009

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Fan doesn't work in heat mode it works on all other functions. Heat does come out but fan doesn't kick in. Outside unit is operating


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Nov 01, 2015 | Heating & Cooling

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 my American Standard heat pump compressor and condenser fan run when I have the thermostat set to emergency heat?


It's possible the "brain" thinks it can still supply some heat. Other wise there is a wiring problem or thermostat switch problem. Installed recently? Never used emergency heat before? What is your emergency heat type, gas or electric? Are you sure they are working. If not the "brain" senses and uses the only source available: heat pump. Thermostat? probably Honeywell? If so call Mfg customer service. Warranty on thermostat or heat pump? If so call customer service. Call your installer.

Feb 28, 2015 | American Standard Heating & Cooling

1 Answer

Why contactor on heat pump will not energize heat mode?


Heat pump and AC are basically working the same principle. When you turn on the heat pump is just like to turn on the AC. The main contactor will energize to turn on the compressor. The only difference is the 3 way valve, either switching to AC mode or heat mode. It is the most commom problem for heat pump. Check the thermostat wires for heat mode and defrost control.

Feb 05, 2015 | Heating & Cooling

1 Answer

The difference between the heat pump and condenser


Well...they are kinda the same. The condenser is where the refrigerant is condensed from a gas to a liquid. When in AC mode this happens outside at the AC unit. (You ever put your hand over a running AC unit in the summer? Feels warm!). When in Heat Pump mode the process is reversed. Instead of condensing the gas to liquid outside (which creates heat) the condensing happens inside and helps warm the building up (with the help of the fan of course). So essential the condenser is where the gas is condensed into a liquid, which creates heat. A heat pump can reverse the direction of the flow and cause this condensing to happen either outside or inside.
This is a very watered down version of what happens but I hope this is sufficient for what you are asking.

Jun 29, 2014 | Goodman Heating & Cooling

1 Answer

Condenser won't kick on, and is hot. Fan works? What's should I do?


Check whether the AC is on fan mode. There are two mode for this type. FAN and AC mode. Put it to AC mode and set the temperature. Solved!! :)

If it doesn't work, call the AC repair guy.
1) Either there will be error with the capacitor circuit which triggers the condenser.
2) there is an issue with your condenser and the circuit.

This is a small repair.

Jun 16, 2014 | GE Zoneline Deluxe Series Cooling &...

2 Answers

Carrier 38CKC042300. oUTSIDE UNIT FAN WAS TURNING REAL SLOW. ac UNIT IS OFF BUT FAN TO OUTSIDE UNIT IS STILL TURNING. sHOULD NOT BE TURNING AT ALL WITH AC UNIT OFF


The outside fan may run if the unit is in defrost mode this is normal for most heat pumps it is there way of trying to keep the outside unit from staying iced over so the next time the unit runs it will have air flow through the coil and the ice will not be there to prevent air flow.

Jan 12, 2010 | Carrier 38CKC042 Air Conditioner

1 Answer

Aprilaire 600: water only runs in "Emergency" Heat mode


When your unit is on normal the outside unit works and the inside only the fan runs. your heat pump does not remove any humidity when it operates so the installation cotractor did not wire it to operate then. you can change the wiring on the humidifier to operate all the time by wiring it to the fan (g) terminal then it should work just turn it all the way to the lowest humidity when you are in cooling mode.

Jan 07, 2009 | Aprilaire 600 Humidifier

1 Answer

BLOWER MOTOR PROBLEM


If the thermostat isnt set to fan on, and the temp in the house is ok, there is probabily a fan off delay in the units circuit board thats defective.

Dec 30, 2008 | Carrier 38CKC036 Air Conditioner

1 Answer

No heat


Your compressor sounds like isn't working? And the problem is if we are lucky you just lost the capacitor. turn off the breaker to the ac/heat pump unit. Open the electrical panel on condenser locate the capacitor if it is swelled up like puffed up can then for sure it is bad. It has two sides to the capacitor one for the fan and one for the compressor. If you have a meter check it in ohms. If you don't have a meter take the capacitor to a heating and air conditioning parts house and get a new one just like the one you have very important to get right size. let me know how it turns out. ken

Dec 20, 2008 | Carrier 38BRC048 Air Conditioner

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