Category Archives: Refrigeration

Replace Air Conditioner Compressor | HVAC Refrigeration

Replace Air Conditioner Compressor Decision | HVAC Refrigeration Question

Replace Air Conditioner Compressor | HVAC Refrigeration – Question – Richard – I am an HVAC technician and have read all of your articles on refrigeration and compressors. Great information and it has helped to hone my skills and offer better service for my customers. Thanks! I was wondering what your experience is with replacing compressors. How do you arrive at the decision to replace a compressor technically speaking of course? I look forward to reading your answer. Brett

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Air Conditioner Condensing Unit Frozen | HVAC Troubleshooting

Air Conditioner Condensing Unit Frozen | HVAC Troubleshooting

Air Conditioner Condensing Unit Frozen | HVAC Troubleshooting

Old Condenser

Richard – Early last month we turned our air conditioner on and it worked fine for a few days. Then I noticed it was getting a little warm in the house so I went around and checked the Air Conditioner. Of course I checked the thermostat first and then the air filter. I went up into the attic to look at the air handler. I did not notice anything out of the ordinary that I am not used to seeing but I am not an expert. Then I went out to the the condensing unit on the back patio and I saw some ice inside the condensing unit. The compressor and the all the pipes connecting to the compressor were a block of ice and frozen solid. I turned everything off and called the HVAC contractor I am used to dealing with. They told me they would send someone out to take care of it. A few hours after making the call I got a call from the technician. He told me there probably very little he could do for me now as we would have to let the ice melt before he could properly troubleshoot the problem. We agreed for him to come the next morning to check it out. He told us to leave the air handler blower fan on but make sure the condenser was off. He told me to go to the breaker box and turn the condensing unit off and use the thermostat for Fan Only operation. We did exactly as he said.

Air Conditioner Condensing Unit Frozen | HVAC Troubleshooting – The Disaster

To make a long story short sometime during the night the pan(s) under the air handler filled with water and spilled over. Eventually the ceiling became waterlogged and caved in all over our living room furniture. It was a mess and terribly upset my wife. It’s been a few weeks and we have finally got everything back to normal again including having the air conditioner repaired. What I want to ask is: Should I ask the contractor to pay for the ceiling and cleaning up the mess? I had no idea the air handler would flood over like that and make a mess of my living room? He was the professional so shouldn’t he have known? I just keep thinking he should of at least warned us that this would be a possibility? I like your advice and often recommend your site to others. Can you please sort this out for me? Thanks – Carl

Air Conditioner Condensing Unit Frozen | HVAC Troubleshooting – Advice

Carl……….I have seen this happen before but not in the order that it happened to you. I often tell people to do the same thing when I get a call and the customer tells me their is ice on their condenser or air handler. Sometimes the ice is on the pipes or refrigerant lines but wither way if you can visibly see the ice on the outside on the inside there is probably a ton of ice especially inside the air handler where the evaporator coil is frozen solid. When you find a frozen compressor or one with as much as you describe inside the condensing unit I can guarantee you have a frozen evaporator coil inside the air handler unit. The freezing can be for various reasons but a frozen air conditioner whether the evaporator coil is frozen or the condenser is frozen is not good and will not function properly until you get rid of the ice and fix the problem of what caused the air conditioner to freeze up in the first place.

Air Conditioner Condensing Unit Frozen | HVAC Troubleshooting – Heat Pumps


Now we could also be talking about a heat pump system in cooling mode. Heat pumps can freeze up in cooling mode also as a heat pump is an air conditioner. Heat pumps also freeze up in the winter but that is for different reasons than the cause of it freezing up in the summer or when the heat is operating in the cooling mode and the condenser or evaporator coil freezes up.  In this situation, whether you have a heat pump or an air conditioner the cause of the condensing unit freezing can be the same problem from the heat pump to the air conditioner. In cooling  mode, either an air conditioner or a heat pump should never produce ice or freeze up the condensing unit.

Air Conditioner Condensing Unit Frozen | HVAC Troubleshooting – Troubleshooting the Problem of a Ice in the Condenser – Airflow and the Evaporator Coil

One thing I always tell my customers is that airflow is very important. If you do not have airflow across the evaporator coil then your air conditioner or heat pump will not cool. I have written this before and I can’t repeat it enough. Make sure you have enough air flow because the evaporator coil needs to be absorbing heat from the air passing over the coil. If it does not then you are simply wasting energy. It comes down to a few things here but the homeowner can check these things to find out for themselves if it is the problem except under the circumstance of when the evaporator coil is completely frozen over.

  1. Dirty Filters – the homeowner can make sure that the air filters are not clogged and preventing the proper amount of airflow from going through the system. Dirty and clogged air filters will cause an air conditioner or heat pump to freeze up.
  2. Collapsed or broken duct work can also cause a problem with air flow. Perhaps the cable man came over to fix something or some other work was being done and they accidentally did something to cause a problem with the duct work. It has happened before in my experience so don’t rule it out.
  3. A bad blower fan motor. Happens from time to time. A bad run capacitor or even the blower motor failing altogether could be the problem.

Another issue that could cause the air conditioner to freeze up is the condenser will continue to run when the air handler shuts off. That is an electrical problem that keeps the condenser running when air handler shuts down normally as it should. The problem is in the condenser and quick fix by an HVAC technician.

Other than that what would cause the evaporator coil or the condensing unit to freeze up is a low Freon or refrigerant charge. I say Freon only because a lot of people refer to their refrigerant as Freon. Technically it is a specific type of refrigerant that could include Freon. In that case a refrigerant leak check is on order to make sure the refrigerant does not leak out again. A repair of a refrigerant leak is specialized and can take some time but a true profession can take of a the problem and offer you a warranty on their work.

Now, Carl, as far as your ceiling is concerned it is nearly impossible to see every possibility with every customer. I am only guessing but it could be the drain on your air handler was clogged. The condensation drain that drains the condensate off the evaporator coil can become plugged up and spill over. It is possible that both condensation drains became clogged. In that case a float switch should of been installed in the secondary drain pan so that in the event that pan over flowed it would kill power to the unit. Who did your annual maintenance? If no one then you can only blame yourself. If it was done recently I would have some questions for the contractor that did the annual maintenance on the air conditioner. I would say turn it in to your homeowners insurance and leave it there. Good luck Carl and I hope my answer helps you.

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High Performance HVAC Air Conditioning and Heating SystemsAir Conditioner Condensing Unit Frozen | HVAC Troubleshooting



Delay Timers and the Air Conditioner Condenser | HVAC Control

Delay Timers and the Air Conditioner Condenser - Unit with the top off - condenser fan motorDelay Timers and the Air Conditioner Condenser – Heat Pump Condenser

Air Conditioners are big HVAC refrigerators. Air Conditioners and Heat Pumps use the HVAC refrigeration cycle to transfer heat from a place where it is not wanted (inside absorbing heat with the evaporator coil) to a place that makes no difference (outside using the condensing unit)(in the cooling cycle). The heart of any HVAC air conditioning, heat pump, or refrigeration system is the compressor which pumps the refrigerant through the HVAC air conditioning system. When the refrigerant leaves the compressor it is compressed and therefore a higher pressure than it was before it entered the compressor inside the condensing unit. This pressure remains constant (give or take under certain conditions) until it passes through the metering device where the pressure and temperature are reduced. This low pressure remains constant (again give or take under certain conditions) until it again reaches the compressor inside the condensing unit and is compressed again.

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Copper Versus Aluminum Coils – Condensers and Evaporators

Copper Versus Aluminum Coils - Condensers and Evaporators

Copper coils covered with aluminum fins

Copper Versus Aluminum Coils – Condensers and Evaporators – Some manufacturers are starting to transition from copper coils to aluminum coils for both condensers and evaporator coils for various reasons. When making a decision to purchase a new system you need to inform yourself about the pros and cons of purchasing a system with aluminum coils or copper coils. Traditionally, copper was the chief choice to use to manufacture evaporator coils and condenser coils because of heat transfer rate, cost, pliability (easy to bend and swage), and because copper line sets are used to join split systems. The cost of copper has skyrocketed and that was a game changer. Many manufacturers have started looking at aluminum because the cost of aluminum is cheaper than copper and aluminum has some of the same benefits of the above mentioned properties that copper has. 

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Compressor Overheating Troubleshooting | Diagnosis and Repair

Compressor Overheating Troubleshooting - Diagnosis and Repair

Compressor Overheating Troubleshooting

Compressor Overheating Troubleshooting - There are some problems with an air conditioner or heat pump system that can be avoided with proper maintenance. Other problems result in a mechanical or electrical problem with the systems that needs to be resolved. Compressor overheating is a serious issue that can cause serious problems with your air conditioner or heat pump system. A compressor that overheats can still operate and provide effective cooling or heating but if the temperature inside the compressor rises too much then the oil in the compressor can break down and reduce the lubrication and cooling effect the oil has inside the compressor. This leads to possible mechanical failure and other problems that will occur to the compressor and in the refrigeration system that results from compressor overheating. When the oil becomes overheated it changes chemically and other a lack of lubricating and cooling effects it becomes like an acid. This eats away at the windings and will cause compressor failure.

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