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I have been working on a Goodman Heat pump. The indoor coil keeps freezing. Outdoor temp is 70F and indoor is 78F. It has a brand new air filter. My superheat is 2F and subcooling is 10F. I have replaced the blower motor. This is a 2.5 unit, my return duct is 12x14, there is a return grill at the return side of the furnace 8x8. It has been working fine for the last couple of years. If I take freon out my superheat become -2. I think I got an airflow issue, and that's why I replaced the blower motor. Return duct is not obstructed or anything. Any idea what might be going on? Also my TD is 19F.

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Hello
Is there a high speed setting for the blower motor.Check the specs on the rpm requierd for the unit.

Posted on May 17, 2011

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Goodman gph1348m41ac unit is blowing cool air in heat mode with mid 30s ambient outdoor temp. I turn it off then on and will usually blow warm air but this cycle is becoming more repetitive. any expert...


A heat pump on the optimal heating day (about 50 degrees ambient) will only deliver approximately 85 degree air as compared to 125 degree air from a fossil fueled furnace. The colder the outdoor air is the less heat there is available to be transferred to the living space. At 30 degrees, the heat transfer capability is getting close to negligible meaning the run cycles will be approaching continuous and eventually as the heat pump along cannot maintain setpoint, the outdoor stat or stats will bring on auxilliary heat in the air handler.

If your ambient temp is below the 'balance point' of the heat pump, the house temp will drop a little lower and most times energize the heat strips through the outdoor t-stat. Your outdoor stat could be set too low for the heat pump to carry the structure all the way down to the balance point so when you turn it off and back on, the lower indoor temp automatically brings on the heat pump plus a heat strip or two, thus the warmer air. Second stage on the stat satisfies due to the heat strip, drops them out of the circuit and the heat pump is left running on first stage heat delivering the perceived cold air.

Your outdoor stat could also be not functioning correctly and not allowing the heaters to come on until the system is turned back on reestablishing the two stage call for heat.

Tons of possibilities and not enough room to list....

Jan 01, 2015 | Goodman Manufacturing Goodman GPH1348M41 4...

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

Ice on coils of heat pump not cooling


Which coil?, indoor or out? Indoor coils freeze due to clogged filters, low freon, blower motor not working. Outdoor coil freezing could mean, in rare cases in cooling mode, reversing valve not shifting.

Oct 02, 2013 | Carrier 52CQ-312-4 Comfort Series Heat...

1 Answer

I have a 2.5 ton ac outside. the indoor unit downstairs in the basement is a goodman. a new a coil was put in about a month ago. which is a goodman product. ive heard goodman is not a good product. a


the inside coil and outside unit should be matching in tonages another word if you have 2.5 ton outside the inside sould be the same. it don't matter what brand name or who made it.

Aug 04, 2012 | Goodman CKL36AR36 Air Conditioner

1 Answer

Above 78F no longer works gives heat head pressure is 300 and slightly above while low side varies bet 45 and 55 psi,noise in the return. i have about 85 feet of coil run 3/8 high side and 3/4 return from...


Your head pressure is a little high, depending on the ambient temp and your suction pressure is a little low. The suction pressure should be around 68 psig, the equivalent of a 40 degree coil. You can try adding a little refrigerant, check your compressor amp draw. If head pressure keeps going up and suction doesn't come up you may have a restricted metering device or filter dryer

Jul 17, 2011 | Goodman Heating & Cooling

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

Outdoor heatpump unit,twx736a100a2, coils freeze over solid,replaced outdoor thermastat, checked freon and replaced a relay switch at a cost of $500/for 2 service call-outs.It worked fine whole month of a...


Coils freezing due to dust blocked coils and or air filter or short of gas. Service your unit completely.Please do not change any spare/s without knowing exact problem. Please follow the steps given below.

Toget proper heat, keep your temp setting at 30+ degree and also mode in "heat"position. If still no heat, check your heating sensor for closed circuit by anOHMs metre.It it's with RV, check power to RV.If it's with heatingelement check power to element. If power is there but still no heat meanselement defective. Replace new heating element. Thanks. To get proper cool, keep the tips as follows:
1. Check air filter is cleaned. 2. Check indoor coil is cleaned. 3. Checkindoor blower motor is working. 4. Keep in cool mode. 5. Set temp minimum 3degrees less than room temp.6.Check compressor is working with correctpressure.
Thanks. Helpful?

Jan 04, 2011 | Heating & Cooling

1 Answer

My 4 ton goodman heat pump goes into defrost and than after the cycle return in cooling stage at least the indoor coil starts freezing is the expansion valve working corectly


The reason for indoor coil freezing due to coil dust blocked-(Clean coil). 2. Less rpm of indoor f.motor. (Replace capacitor). 3. Short of gas. (Find leak and repair and then recharge gas.)

Jan 04, 2011 | Heating & Cooling

2 Answers

Indoor unit temperature between 60F & 70F after R22 charge..


The pressure changes with temperature, it is not a true gauge to ensure a proper charge.

You should have a 15 to 20 degree temp drop across the evap coil. (return air vs supply air)

Can you verify that the compressor is running?
Not the condenser, but the compressor located inside the condenser (outdoor unit)

it really sounds like it is still undercharged.
Check the temp drop, let me know what it is.
Also tell me what the outdoor ambient temp is.

( for example.... 98 degree outdoors with 85 degree indoor temp could result in pressures something like 325 on the high side and 75 or 80 on the low side.
With the exact same unit, but 80 degree outdoor temp combined with 70 degree indoor temp, your pressures could read 215 low side and 55 low side. Not to mention that more efficient units often have higher pressures on the low side because they have more coil space and remove heat more efficiently)

Aug 21, 2009 | Sanyo Split System Air Conditioner

1 Answer

I am working on a coleman self-contained a/c which is low on charge. it is for my sisters mobile home, what should the pressures be. Any other ways to check charge? The model # is 7330D901. Thank you very...


If it uses R22, with a 70F to 75F indoor temp, and a 70F to 80F outdoor temp, I would think the suction pressure would be 65 to 70 PSI. Liquid line pressure might be 200 to 250 PSI. On a warmer day, they could be higher. Granted, those pressures are for the cooling mode. If it is a heat pump, the pressures will be higher in the heating mode.

Jul 07, 2009 | Coleman Heating & Cooling

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