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Reversing valve Model: PHJ030-1A Seral: 9705062008 The reversing valve is not reversing to heat. I found a small hole at the condenser coil, with oil residue around the "U" shape joint. When the heat stop, the condenser froze up. I think the a/c part will continue to cool with low pressure. Could low freon keep the reversing valve from switching. Reversing valve need more pressure to work. I check coil, the ohms is 17.6, and I do have 24 volts going to the coil, but I did not check it in cool for 24 volt. What should the pressure be in temp of 50's to 30's, so I know what to do.

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Re: reversing valve

The first thing you need to do is fix the hole in the coil. It will only get worse no matter what you do. The reversing valve is controlled by the thermostat, then to the defrost board, as it has a timer, sensor and all that jazz. As to your question, that is a tricky one. The way I found worked best for heat pumps is to turn it to cool. If its so cold outside that it will not turn on because of an outside thermostat, cover the coil and yourself with a cardboard box or a large tarp. Give yourself some room of course, get a set of gauges that has temp. ring for R-22.Take suction temp. from the line about 1 foot from the compressor, look at the low side of the gauge and find the temperature, not the pressure for R-22. You should have a 20 degree differential. If more than 20, add freon, less remove. This sounds a little odd, but its easy to overcharge heat pumps on the heat mode. The condenser has a sensor that switches on the electric heat if the heat pump is not working. Ice on the condenser is normal on heat mode, that's why there is a defrost board.

Posted on Jan 12, 2008

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I'm a hvac technician myself looking for some advise

if it is a heat pump you could have a clogged actuator piston or a stuck reversing valve depending on whether the unit is energized in the heating or cooling cycle. Try pulling the wire on the reversing valve coil on and off a few times and that may force it to unstick. There is a lubricant that you can pour directly into the true suction line above the reversing valve itself. Supco oil is the name i believe. Also can try removing the actuator piston at both the condenser and the evaporator and checking to see if there is some trash in the line, especially if the lines were brazed without using nitrogen.

Jan 29, 2013 | Air Conditioners



What is a condenser?
Is a device or unit used to condense vapor into liquid. A condenser is simply one component of an air conditioner. Whether you have an outdoor air conditioner or a window unit air conditioner your air conditioner contains a condenser.
Condensers are used in outdoor air conditioning systems as well as heat pump systems. Condensers in an air conditioning unit have very few controls. They will have an on and off switch. Occasionally these air conditioners will also have a brown out option. This option shuts down the compressor when the electrical current is low.
A condenser is simply a heat exchanger. It compresses refrigerants into a hot gas to then condense them into a liquid. A condenser is a major component in a air conditioning or heat pump unit. It moves air across the coils to facilitate the transfer of heat.
In a heat pump unit the condenser has a few more features. It will have a reverse valve that allows the unit to switch back and forth between air conditioning and heating. Even when the unit is heating, it uses the condenser for defrosting the coils. If the coils become layered with frost it will effect the units effectiveness this is defrosted when the reverse valve switches to air conditioning mode to move the hot gases through the coils melting the built up ice. It will automatically switch back to heating mode once the ice is cleared to once again heat the home.
To keep your unit in good operating condition it is vital to keep the area around the condenser clear of all debris as well as keeping the filter clear of dust and dirt. A clean machine makes a happy machine. A happy machine will keep you cool during the summer months and warm during the cold months. It is suggested to change the units filters when they become dirty, depending on your area and conditions near your home this may be as often as once a month or as seldom as every 3 to 6 months. You will have to pay close attention to your units needs to decide the right time to change or clean your unit’s filters.
It is very important no matter what type of unit you have to prevent the blockage of the condenser. If the condenser becomes block it can effect the units efficiency or even cause the until to completely fail. For this reason it is one of the most important components of a cooling or heating system. A condenser allows the maximum airflow to the unit.
Keeping you condenser in good running condition will not only prolong the life of your heat or cooling system but also provide you with the most efficient heat and cooling system saving you money on heat and

on Apr 08, 2010 | Air Conditioners


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 loud buzzing noise if you have heat pump. May be comming from your reversing valve. To quiet this down. Turn off power to outside unit and squirt some oil into the reversing valve coil area. The coil slides onto a shaft this shaft has corroded a liitle and does not let the valve center itself. Alittle oil on the shaft help and quiets this down. DO REMOVE THE COIL WITH THE INSIDE AIR HANDLER POWER ON IF YOU HAVE POWER TO THE THE COIL AND REMOVE IT IT WILL BURN IT UP. yOU CAN JUST UNPLUG THE COIL IF YOU LIKE. RUSS

Jul 18, 2009 | Air Conditioners

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I have a heat pump that when turned on the tube get cold and condensation develops but 45 seconds later cooling stops and compressor keeps running. the coil for the reversing valve is not energized, there...

Sounds like low on freon. The suction line will turn cooler upon first start up. Heat pumps do sound scary but you all ready have cked the reverse valve coil, ck the lines in\out temp. If you can ck temps on your suction line vers press. repost if you need more help.

Jul 10, 2009 | Air Conditioners

1 Answer

Reversing valve issues.

You will need to replace the reversing valve. You cannot replace the coil with a remote sensing bulb on this unit. Usually you know when reversing valves get stuck when you are having low side problems with heat working properly

Jun 01, 2009 | Ruud UPMC036 Air Conditioner

1 Answer

Reversing valve not switching over to air on heat pump. compressor will come on for about 10 minutes, then shut off. Hot air comes out vent.

Look for any refrigerant leaks - no or low refrigerant can cause problems in both modes. The unit may be going off on low suction.


The unit may be stuck in the heating mode.

Make sure the system is calling for the correct mode (cooling or heating) - some systems are auto, but if you can, select cooling since that is the requested mode. Check for power at the reversing valve inside the condensing unit. If power exists, then the reversing valve is stuck. It could also be the reversing valve solenoid coil, so make sure that isn't bad. There should be a strong magnetic field at the solenoid coil.

If you can hear the reversing valve clicking (moving), check the T-stat and make sure it will switch modes. Also check the reversing valve relay (those can be located in either the indoor unit or condensing unit).

May 25, 2009 | Ruud Matching Split Air Conditioner

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My intertherm heat pump has freon but will not heat is it posible that the reversing valve is stuck in the middle and will not let it heat if so where can i get a new one. My heat pump cools good and when...

You can't replace a reversing valve (must remove ALL refrigerant first), unless you are EPA certified and have the equipment to recover the refrigerant and to braze the old valve out and the new one in. That said, it's probably an electrical problem anyway. Could be the thermostat, the thermostat settings, the wiring between the thermostat and the furnace and the condenser, or the controls in the condenser - probably not in the furnace. If you don't see anything wrong you're probably gonna need a pro.

May 05, 2009 | Air Conditioners

1 Answer

Lg minisplit heat pump will not heat

You may want to check that the pressure switch is not functioning? Secondly there is also a thermo sensor on the condenser coil which could be faulty.

Feb 26, 2009 | Air Conditioners

1 Answer

Rudd 2 ton 10 S

The small copper line should not be really hot its supposed to be carrying liquid refrigerant which has already had the heat "pressed" out of it by the compressor and carried of by the air flowing over the condenser coil. This could indicate a few things; that your unit is overcharged, you have a mismatched evaporator coil and condenser, an ineffective condenser fan motor or a clogged condenser coil and as a result your compressor is shutting of due to an overload condition from the building heat and back pressure between the compressor outlet and the evaporator inlet.

First make sure your condenser is clean and that adequate air is flowing over the fins of the condenser coil. Then be sure your equipment is a matched system. A indication that your condenser fan motor is not at speed is slow starting a humming sound and excessive heat. In my experience this complaint is generally the result of a bad condenser fan motor that over heats and shuts of after a short period and the build up of heat in the liquid refrigerant line of course trips the compressor overload circuit- which by the way usually takes hours to reset. I hope you've already resolved this, but in case you haven't......

Aug 01, 2008 | Ruud Matching Split Air Conditioner

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