Question about Amana Comfort Zone 18M33PCEH Air Conditioner

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Not heating Unit works on cooling mode, will not work in heating mode..blows cold air.Does reversing valve have a seperate coil or built in

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Re: Not heating

I'm a Certified HVAC Technician and have been working in the industry since 1996. I totally agree with Rob. But, I'm a bit confused in that I have read "Problem with Amana Comfort Zone 18M33PCEH Air Conditioner" but then I read "Not heating

Unit works on cooling mode, will not work in heating mode..blows cold air.
Does reversing valve have a seperate coil or built in"

First of all, an AIR CONDITIONER does not have a "REVERSING VALVE" - only a HEAT PUMP has a REVERSING VALVE. If the THERMOSTAT was REPLACED, did the ORIGINAL COLORED WIRES and ORIGINAL TERMINALS get RECORDED onto a piece of paper? It is imperative that the CORRECT COLORED WIRE within the Thermostat is CONNECTED to the "O" which, on MOST HEAT PUMP Thermostats is the REVERSING VALVE and, in MOST cases is the ORANGE wire. In every HEAT PUMP system that my company has installed, I have directed all of my technicians to use the STANDARD wiring COLOR Codes, regardless of WHAT was previously used. That way, when another HVAC Technician is called, he or she can easily troubleshoot and reduce the amount of time spent on the Service Call, thus saving the homeowner $$$ in the long run. Good Luck!!!

Posted on Sep 20, 2012

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Re: Not heating

Yes, the reversing valve has a separate coil. some energize on cool mode, some on heat mode. Has the thermostat been replaced? I find this a common mistake.

Posted on Nov 04, 2007

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My Home AC blows hot air

You need to check to see if you have 24 volt signal from thermostat to your reversing valve. To go into cooling mode the reversing valve needs to be energized. Orange is normal color of the reversing valve power supply. On your unit will be a reversing valve which looks like a pipe with 3 pipes attached to one side and 1 pipe attached to the other side. On the side of the the reversing valve will be a coil with a 2 wire connection. This coil needs 24 volts applied to shift unit into cooling mode. In your thermostat wire bundle where it is connected, check for voltage between common and the orange wire. If it does not have 24 volts with the thermostat in cooling mode, you have a break in the line normally a connection on the orange junction inside your air handler or your thermostat orange wire is loose. Keep checking for 24 volts available until you find the source of the loss. If you have 24 volts at the reversing valve, you can check to see if the valve is working by unplugging the 2wire connection on the side of the valve, if it clicks its powered if not and 24 volts available then the coil needs replaced.
Any more than this you will need a professional tech to troubleshoot and fix.
Hope this helps.

Jun 21, 2014 | Goodman CLQ36AR49 Air Conditioner


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

My mistral reverse cycle mss25ss model does not work at all in heat mode. what would be broken?

firstly is the air comming from the outdoor unit cold or warm? if it is cold then the 3way valve is working and it has changed to heating. If it stays warm then it is still in cooling mode. The indoor fan wont come on until the coil temp gets warm enough, ( so it doesnt blow cold air on you straight up). If it is changing into heat mode then the larger of the pipes connected to the outdoor unit should get warm/ hot. If this is not happening then the unit is either out of gas or the compressor is on hollidays and wont come back to work.

May 22, 2012 | Air Conditioners

1 Answer

Why is ge ajes12dcc 11600/11400 window air condition/heater combo blowing cold air for heat the air conditioner is working fine but the heater is blowing out cold air

Hi, it sounds to me like your reversing valve is not switching the flow of freon over to heat, stuck in cooling. The valve is located near the compressor, it has a 24 volt coil on it. If you unplug it, it should switch the valve into heat. If not, the valve is probably froze stuck, and will need to be replaced. Something a service tech would have to do.

Nov 06, 2011 | Carrier XHB123D X/Y Series Heat/Cool Air...

1 Answer

Unit will not heat, change batteries controller cleaned filters etc. Still blowing COLD air

Check the thermostat the auto machines, with a reversing valve, there is no heating or cooling, generally, in the sensing temperature band of 19 Deg C to 22 Deg C and it only works on blower mode, re-circulating the room air. When the sensing temperature goes below 17 deg C, it works on heating and when the sensing temperature goes above 24 deg C, it works on cooling

Sep 05, 2011 | Air Conditioners

1 Answer

Indoor fan blowing cold air when on heating

The indoor fan will continue to run. When heat pump goes into defrost the outdoor fan stops, the reversing valve switches and the unit is basically working in the cooling mode. In order for you not to feel a blast of cold air in the winter the electric strip heat also comes on so the indoor fan must run while the strip heaters are on.

Jun 03, 2010 | Air Conditioners

1 Answer

Hi, I have a wall mount midea split a/c model- MSG-36HR that will only heat. when put in cool mode it only blow's room temp air and the outdoor unit won't run. On heat mode it works normally. I have cycled...

Most heat pumps are 'fail-safe to heat'. That is: the normal position of the valve which reverses the function is in the position which provides heat. The reversing valve must be powered to switch to the cooling position.

Although the lack of valve function could be a mechanically defective reversing valve - it's more likely to be an electrical issue. Start with checking for power at the reversing valve's coil. If it's powered unpower it - you will be able to hear the reversing valve distinctively

Oct 03, 2009 | Midea Air Conditioners

1 Answer

Heat Pump and fan work fine, but will not blow cold air on AC setting

The reversing valve coil may be bad or no power to it during cool. Most heatpumps are set to have the coil of the reversing valve energize in the cool mode. The heating mode is the fail safe mode if the rev valve fails to energize. Check this and let me know.

Jun 18, 2009 | Dometic Rooftop RV Air Conditioner

1 Answer

Uotside unit blowing cool air but hot on the inside

It sounds like you have a unit called a heat pump. When a heat pump unit is in cooling mode the outside unit blows hot air and the inside unit blows cold air. If the outside unit is blowing cold then the indoor unit is most likely blowing room temperature or warm air. It sounds like the thermostat could be controlling incorrectly or you could have a failed reversing valve which is the device that switches the unit from heating to cooling mode.

May 31, 2009 | Ruud UBHC Air Conditioner

2 Answers

Heat pump is not kicking in, no heat at 42 degree outdoor temp


Most likely has a freon leak , or a control problem causing heat to turn on, or if you have a heatpump the reversing valve has a problem.

Oct 10, 2008 | Amana PTH123B35AE Air Conditioner

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