Table of Contents
- discussion about HVAC compressor failure and how it is one of the most expensive air conditioner repairs
- comprehensive list of reasons why HVAC compressors fail
- actions to take to prevent compressor failure
- the importance of doing the job right and using the triple evacuation method
- a video on the importance of regular maintenance on HVAC equipment
Air Conditioner Compressor Failure - Air Conditioner Repair
Old Burned Up Semi-Hermetic Compressor from a Chiller
Air Conditioner Compressor Failure - There may come a day when your air conditioner or heat pump system fails to cool your home or business and you call an air conditioning and heating contractor to fix the problem. The HVAC technician arrives and starts the process of troubleshooting the air conditioner system.
About 30 minutes later the HVAC technician reports back to you that your Compressor Overheating Troubleshooting and either need replacing or the HVAC system needs to be replaced.
HVAC Compressor burnout is a serious and costly matter. Replacing the system requires a judgment call on your part. It is based on the cost of the burned-out compressor replacement. If the failed compressor is still under warranty, you might still have to pay for labor. You will likely have to pay for labor to replace the burned-out HVAC compressor for your air conditioner. Additionally, another factor is the current age of the air conditioning and heating equipment and whether you have the money in your budget to replace the system.
Before any of that, you’ll want to know what happened to cause the compressor to burn out in the first place. There are many reasons why an air conditioning and heating compressor can burn up, but the primary causes are neglect. Here is a list of possible reasons an HVAC compressor can burn out. Some of these reasons for compressor burnout are beyond your control, but the things that are in your control need to be addressed on a regular schedule.
Air Conditioner Compressor Failure | Excess Heat - Pressure
Some of the things on this list will cause excess heat inside the compressor. Excess heat inside a compressor is not good for mechanical components, and the oil in the system. Eventually, with excess heat that is outside of design temperatures, metal components will fail or not work as designed, and the excess heat causes the oil to break down and not provide the lubrication as designed, and that leads to more heat. The situation can snowball, and eventually, you have to either replace the compressor or replace the whole system.
Air Conditioner Compressor Failure - Possible Causes
HVAC Compressor Failure - Poor Maintenance to the HVAC system especially the air conditioning or heat pump condenser. Compressors don’t get compressors to burn out because of poor maintenance on the compressor. Many hermetic compressors are maintenance-free, so you need to look at the condenser instead of the HVAC compressor. Over a period of time, the air conditioning and heat pump condenser coils can become clogged with dust, dirt, and debris.
This restricts airflow through the coils and causes pressures and temperatures to rise inside the air conditioner or heat pump condenser including the air conditioner or heat pump HVAC compressor. Under extreme operating conditions, the air conditioner or heat pump compressor has to work harder to compress and pump the refrigerant through the air conditioner or heat pump system.
When the compressor works harder, it pulls more amperage, which causes it to run hotter than normal. If the HVAC compressor exceeds its normal rated operating temperature, things inside the compressor start to break down, and eventually, over time, the compressor will fail, and the result is compressor burnout.
There are built-in protections against compressor overheating, but these protections are prone to failure under extreme conditions or may allow the compressor to run at just below the temperature protection level, but over time this higher than normal temperature will cause the compressor to burn out.
HVAC Compressor Failure - Restriction in the Refrigerant Lines
A restriction can also cause a compressor to burn out. Compressor burnout can occur as a result of a malfunctioning or clogged metering device or damage to the refrigeration line set. The copper lines that run between the condenser and the evaporator coil can be damaged or crimped, which will restrict the flow of refrigerants.
This refrigerant flow restriction causes an imbalance in the pressures of the air-conditioning or heat pump system, which causes the air conditioner or heat pump compressor to work harder. That causes higher compressor operating temperatures and amp draws, which leads to burnout, especially under extreme operating conditions.
A refrigerant line can become damaged when someone steps on or twists one of the copper lines running from the air conditioner or heat pump condenser to the evaporator coil located in the air handler. The damage may or may not affect the cooling capacity of the air conditioner or heat pump system, but it needs to be corrected as soon as possible.
There are instances when the installation crews inadvertently crimped the lines upon installation, and the problem can remain hidden until the air conditioner or heat pump system has a compressor burn out. A good air conditioning or heat pump technician using thorough air conditioning and heating troubleshooting techniques can resolve the issue and prevent a compressor burnout before it happens.
Restricted or Malfunctioning Metering Device | Air Conditioner Compressor Failure Root Cause Analysis
Restricted or malfunctioning metering device can also cause the air conditioning, or heat pump compressor burn out. That can be a complicated problem to diagnose even for experienced technicians, especially when the problem is intermittent. The most common metering devices are fixed orifice metering devices and thermostatic expansion valve device (TXV).
Fixed orifice metering devices can become clogged with trash or even ice up if moisture is in the system, and this can lead to compressor burnout. The same thing can happen with a TXV metering device. However, the TXV is more complex than the fixed orifice metering device, but it too can malfunction and result in a compressor burnout. The TXV has moving parts, and these moving parts can stick, causing the system to experience restrictions.
Burned out compressors that have been replaced before, and two weeks later, the technician is back looking at another burned-out compressor. Because this problem was intermittent and not diagnosed when the new compressor was installed. Now everyone is scratching their heads, the air conditioning or heat pump technician looks bad, and the customer is perturbed. It happens, and the best thing to do is find the intermittent metering device problem and replace the old burned-out compressor.
Moisture in the Refrigeration System | Air Conditioner Compressor Failure
Moisture in the refrigeration system can also cause air conditioner or heat pump compressor burnout. Moisture in the refrigeration system will eventually cause a compressor to burn out and is usually a result of poor installation. The oil in the refrigeration system mixes with moisture and creates an acidic sludge that slowly eats away at the windings on the compressor motor.
The installation technician must use proper installation practices when installing a new air conditioner or heat pump system. Or that the service technician uses the proper methods and procedures when opening the air conditioner or heat pump refrigeration system for any reason. A triple evacuation with a nitrogen purge in many cases will eliminate all moisture and non-condensable gases in the air-conditioning or heat pump system.
That, along with using the proper filter driers will prevent compressor burn-up from moisture. The filter drier should be replaced any time the air conditioner or heat system is opened for any reason.
Oil Loss from Refrigerant Leaks | Air Conditioner Compressor Failure
Oil loss from refrigerant leaks can be another reason for air conditioner or heat compressor burnout. That is common as many people do not want to pay to find a refrigerant leak when the cost of filling the air conditioner or heat pump system up with refrigerant is cheaper. Whenever there is a refrigerant leak, oil from the system also leaks out through the same hole where the refrigerant is escaping.
The proper oil level is necessary for good lubrication and also cooling the compressor. While the air conditioner or heat pump compressor is cooled mainly by the return suction gas, the oil still contributes to keeping the air conditioner or heat pump compressor cool by reducing friction in the air conditioner or heat pump compressor. The best advice High Performance HVAC Systems can offer is that you have the technician find and fix the refrigerant leak.
That will cost more than just filling the air conditioner or heat pump system with refrigerant, but the long-term alternative will cost more. This is especially true for the new R-410A refrigerant systems which operate at higher pressures than the older R-22 systems.
Compressor Short Cycling | Air Conditioner Compressor Failure
Compressor short cycling can also cause air conditioner or heat pump compressor burnout. That occurs when the unit is turned on and off quickly without giving it the proper time to recover, equalize, and cool down. An air conditioner or heat pump compressor pulls a high amp draw on startup, which is technically called locked rotor amps.
The compressor has to start from a full stop to a full blast in less than a second. It also has to overcome the head pressure, and if the unit just quit (within the last 3 minutes), the head pressure is still high and equalizing. Starting and stopping and the compressor continuously under these conditions will create a lot of heat, and this increased heat level can cause a compressor to burn out.
An air conditioner or heat pump unit with the proper controls that prevent short-cycling will prevent compressor burn up under these circumstances. Much modern digital heating and cooling thermostats have built protection for short cycling. The thermostat has a built-in time delay which prevents the user from turning the air conditioner or heat on and off and on again too quickly.
Refrigerant Contamination
Refrigerant Contamination - If the system was recovered of refrigerant and the recovery tank contained contaminated refrigerant and acid from an old burnout, the contaminated refrigerant will cause problems. Eventually, the acid will cause compressor failure. If the technician cannot do a refrigerant pump-down method into the condenser then it is best to use virgin refrigerant on the refill after the triple evacuation of the system.
Liquid Slugging
Liquid Slugging - this happens when the evaporator is not absorbing enough heat, and liquid refrigerant makes its way back to the compressor. The liquid does not compress and will cause irreparable damage to a compressor.
Defective Compressor | Air Conditioner Compressor Failure
A defective Compressor can also be the cause of an air conditioner or heat pump compressor burnout. That is not very common, but it does occur. Hopefully, if this happens to you, the air conditioner or heat pump compressor is still under warranty. Either way, the technician needs to look at the other issues described here before determining that it was a defective compressor.
Other issues to look at in the air conditioner or heat pump compressor system are the compressor motor capacitor and the proper amount of voltage the compressor is getting. The capacitor and the voltage should fall into plus or minus 10 percent of the rating by the compressor manufacturer. Anything out of this range can cause problems that lead to compressor burn-up or burn-out.
Lightning Strikes
Lightning Strikes can fry an air conditioner or heat pump compressor and other HVAC components in the air conditioner or heat pump system. In this case, hopefully, your insurance will cover the cost of replacing the air conditioner or heat pump. A large amount of voltage and the current passing through an air conditioner compressor that is running can have devastating effects the may damage the system beyond repair.
Conclusion | Air Conditioner Compressor Failure
While compressor burn-out is quite common for compressor failures, another common problem is compressor lock up. An air conditioner or heat pump compressor is a mechanical and electrical device. It has mechanical parts which are driven by an electric motor. If the mechanical parts lock up or seize up and the electric motor in the compressor does not have the horsepower to overcome the lock-up or seizing of the mechanical parts, then the compressor is mechanically locked up.
There are techniques a good air conditioning, and heat pump technician can use to unlock the compressor, but approximately 25 percent of compressor lockups cannot be unlocked. It becomes necessary to replace the air conditioner or heat pump compressor or the whole condenser. The important thing is that you have a regular maintenance schedule for the air conditioner or heat pump system to prevent most problems that can cause a compressor to burn out, burn up, or mechanical lockup.
Video | Air Conditioner Compressor Failure
Air Conditioner Compressor Failure Helpful Video - Here is a video of a man explaining preventive maintenance on condenser coils. Dirty condenser coils contribute to burned-out compressors.
HVAC Compressor Failure
Technical Resource: Refrigeration and Air Conditioning Technology
Given extreme freezing conditions like -5 below and temps below 32 for 7 days, is it possible the heat pump could have frozen and then Liquid Slugging occur locking up the compressor. If so, what steps would have to be taken to determine this was the cause for he compressor to fail?
I have a Lennox 5 ton furnace and the air compressor on the heat pump went bad a few months ago, I ended up having a new Goodman 5 ton heat pump installed with an A coil to go to the Lennox furnace in which the tech. wanted to sell me a new furnace also but I did not have the extra money for it at the time. At any rate the new heat pump kept freezing up if I put the thermostat below 73 degrees, then the capacitor went bad and I had a different company come out and they told me that there was a 5 1/2″ gap behind the A coil which could be causing the freeze ups, would that also have caused the capacitor to go bad since the capacitor in the heat pump was still new
No, I doubt it made the capacitor go bad. When I first read your story I was thinking it was an airflow issue and a 5.5-inch gap will cause an airflow issue.
Seems like whoever installed the system didn’t really know what they were doing. Without proper airflow, the refrigerant charge will also be off. Hopefully, the second guy recognized that and took care of everything for you. And it’s not uncommon for capacitors to go bad.
On May 1, a scheduled maintenance was performed on my AC. It is a Trane 12 yrs old. The tech did a complete inspection of all AC parts and stated everything is working correctly. No concerns or problems. On July 6 I turned on AC for 1st time and very little airflow and definitely not cooling the inside. Another Tech came out following Monday and after pulling out the disconnect we noticed one side had melted. Additionally, the compressor was determined to be grounded. How is it possible for a disconnect to melt and a compressor become useless over 2 months when it is not used and especially after the original Technician said “AC is working correctly”? The AC company has no answer only that it happens.
Not sure how it could have happened except for a mechanical/electrical issue or possibly a lightning strike.
We had a technician checked our AC and found that one small compressor is dead short/grounding as he said. He then proceeded to disable the cable so that our AC can run on the bigger compressor. After 3 weeks, we had another technician came to check and found that both compressors are broken. Another with open wiring. Does having one compressor run cause it to break?
No, but I would call and get a second opinion from another company. It may be true but it sounds a little fishy to me. Sounds like you have one of the older systems that has staging with two compressors and from my experience the odds are way out there that both failed in the frame you are describing in the same way. Try another company for the second opinion. Some companies pay their technicians a commission for selling new equipment and sometimes that policy creates dishonest technicians. I’m not saying those techs are being dishonest but it is possible. A compressor is a major component and if it fails in an older system it is best to replace it. That means big dollars and a major job so get a second opinion before doing that. It will cost you for the service call but it can also save you a lot of money if the new company finds a simple problem and gets the oldsystem running again.
What does it mean by a compressor has dead short? Do I have to replace the entire compressor?
Yes on replacing the compressor. A dead short is a bad winding in the compressor motor. The windings are either touching each other or one of the windings (copper wire) is touching something it should not touch and there is no repair for this as the compressor is hermetically sealed.
12 year old Coleman 2 1/2 ton heat pump had failed compressor at 4 years. Tech replaced, then 3 days later he was back out because new one also failed. Since then, I am constantly having issues with leaks (Condenser coil fitting, plugged filter from discharge line, reversing valve at center port) and of course they have to add coolant every time. Now there is a leak that they say cannot be repaired and whole unit needs to be replaced @ $4300. I have paid over $1300. in service calls. Feel like I’ve been paying for incompetence. At what point should Coleman have been contacted about this unit?
In my humble opinion, and it is backed up by others in the industry, is that much of the HVAC equipment they sell these days are good for 13 to 16 years when properly installed and maintained. Within that time frame the industry has made improvements and the efficiency levels have jumped not only through mandates but also innovation from the ever changing and improving technology. So either way it makes sense to replace the equipment after that time especially if are having or have had several problems with the equipment as you have described here. A good manufacturer will offer a good warranty for their product.
I know Daikin and Maytag have some warranties on select equipment that include 12 years limited parts warranties. Of course, always read the fine print and understand many of these warranties do not include the cost of labor, as you may well know.
The point being, if someone is going give me a 12 year warranty on something that has many moving parts I’m thinking they make quality products. Products that are reliable and will not break down that often.
I think the most important part of selecting any HVAC equipment is selecting the best HVAC contractor to install the system. I’ve seen problems occur because of poor installation. Proper installation is a huge factor in the proper and reliable operation of the equipment. It also makes a big difference in efficiency of the unit also. For help, you can use the provide links to find a good HVAC contractor and to read more about proper installation, reliability and energy efficiency. You can also use our free HVAC Buyers Guide to help you. We have tons of information here to help people especially when make buying decisions concerning HVAC.
Sorry you have these problems Juli. There is probably nothing Coleman will do at this point. Outside of the warranty they have no liability and will likely tell you this if you contact them. You can make a review of your Coleman describing everything you experienced with their unit. That will let other people know, good, bad, or ugly about your system. You can also browse our reviews to make a decision on your next new system. I also emphasize to homeowners purchasing new equipment to make sure you do your homework especially on the HVAC contractor. We have provided all the information here on this site to help you so make it a part of your homework. Good luck!
I recently had my Heat pump serviced for a leaking valve. The unit was under warranty but the large amount of freon was not. Three weeks later I have a compressor that is not working> The technician says I need to replace all the freon again because the freon could be bad. Is this likely in 3 weeks? Have run the heat very much and just started using the AC again when we noticed the issue.
The only reason the refrigerant goes bad is because it gets acid inside it usually from moisture. Moisture in the system is typically the result of poor installation practices and not properly evacuating the system before charging the system with refrigerant. See https://highperformancehvac.com/hvac-triple-evacuation/ for further details. It really depends on the original problem with the compressor. Was it a burn out? Did the windings burn up? If so, then the system should have been flushed before charging with virgin refrigerant otherwise the residual oil left in the system will likely cause the new compressor to burn out simply because the oil holds acid. Not sure what happened in your case but refrigerant simply does not go bad or burn up by itself. There are some other underlying factors causing the issue.
Very informative.
My outdoor unit will run for 1-2 seconds then turn off, then back on again for 1-2 seconds again. Ive changed the capacitor, the contactor, an installed a hardstart kit, an it still wont say on. What could be causing this?
Can’t really say 100% without looking at it but on the face of what you said it doesn’t look good for the compressor. Again, without looking at it I can’t say 100%.
Without readings diagnosis is difficult. It could be shutting down on thermal overload because of overamping caused by locked rotor or bad start devices. Another cause could be low pressure or high pressure switches. Possible causes for these are low refrigerant and low air flow, inside or outside.
Shorted compressor unit.
I have a compressor unit that is shorted, as a result the capacitor cap blew-off. The system is cleaned and maintained. Filters are cleaned, coils are cleaned no air flow restrictions. The unit is about 14 years old. My warranty tells me the compressor shorted because of poor maintenance. Are they right? what could cause the compressor to short out.
If everything is as you say it is then take pictures of the unit. Also, hopefully you had an HVAC company performance maintenance from time to time on the system. If so, call the HVAC company and get them to send you a letter saying they performed routine maintenance on the system. I would say a lack of maintenance is a possibility but they are likely taking a shot in the dark trying to wiggle out of paying for that compressor. Too much heat inside the refrigeration circuit could cause degradation but most of these systems are designed with overload protection.
A warranty company has come out and replaced my fan once and compressor twice in the last three weeks. The unit worked for 15-20 min each time then the compressor burnt out. They are now saying that the need to replace the metering device and compressor. Before they could, they called today and said they reviewed the pictures and its dog urine causing the compressor to ground. Is there any truth behind this? What else could it be? Also, unit is old (15-20 years) but super clean, no rust.
That is impossible as the refrigeration system is hermetically sealed and impossible for dog urine to get into the system unless the dog knows how to inject the urine into the refrigeration circuit. I’ve seen dogs pee on condensers and cause corrosion on the coils. Dog urine could also cause the wires on the outside of the compressor to corrode but unlikely because the wires are inside the condenser. An educated guess as to your problem is that the system had moisture in it some how. Perhaps when maintenance was done. Acid is the primary cause of burnouts. Moisture mixes with the oil in the system and it creates an acidic sludge. The acid eventually eats away at the protective coating on the windings inside the compressor and that causes a dead short.
Given the age of the system I would recommend replacing the system. It’s really not worth it spending the amount of money replacing the compressor when you can get a newer more efficient system that will likely be trouble-free compared to what you currently have. Probably a good idea to start thinking about it.
Since the home warranty is on the hook here and they are doing everything they can to wiggle off the hook get them to replace the compressor but you want a competent company to do the work. The entire refrigeration circuit needs to be flushed with a chemical to get rid of all the acid in the system. And yes, it is probably a good idea to replace the metering device. After the system is flushed a proper evacuation of the system is necessary. Use our search feature to search for triple evacuation to find out about that. If they do the job right and use correct procedures then your air conditioner should be up and running again with no further problems.
But again, highly consider replacing in the near future. You will save money on your electric bill.
I have a Rheem ac u it and the coil in the attic had a leak. We had let it run for about 24 hours before we shut off the compressor. I have replaced the coil and the capacitor since it was leaking and now the compressor wont start. It ran for 2-3 seconds after it was charged but thats it. Any suggestions?
its difficult to answer this question without actually looking at it myself and knowing the history. Was it properly evacuated before being put back into service? Was virgin refrigerant used for the recharge? There are to many variables here to properly answer the question with a definitive answer. Electrically and mechanically.
I have a new 2 ton Trane a/c cooling unit. It ran for about 3 hours while completely depleted of refrigerant. Will this shorten the life of the condenser?
the compressor likely tripped on overload or if equipped with low pressure switch then the low pressure switch would kill the compressor if there was no refrigerant in the system. It’s hard to say if the life was shortened as the compressor is hermetically sealed. The only way to tell is to fix the leak, evacuate the system and then recharge it.
thanks a lot for the information…i have a AC unit and is burned for 3rd time..i going to check the refrigerant , gas lines , metering device…i hope to find the problem…could you comment about electrical failure?..My Ac unit is a triphase and could burn the motor if the motor is running in the opposite direction as to be?….
I am assuming when you say triphase you mean 3-phase motor? And if it is a reciprocating compressor the rotation does not make any difference unless specified by the compressor manufacturer. The piston and valves will working the same no matter the direction the motor is turning………..again unless the compressor manufacture has specified the rotation it does not make any difference. If you are replacing the compressor for the third time then something is definitely wrong. If it is an electrical burnout then the entire system needs to be flushed including the line set, condenser and the evaporator to remove the old oil from the system as the old oil will contain acid that would cause the burn out. Flush kits are available at an HVAC supply house. If it is a mechanical problem then you likely have an oil issue. Either getting too hot and breaking down or circulation. Also the oil level is important. Most three phase compressors have an oil level indication on them so regular maintenance checks can be made to ensure there is plenty of oil to lubricate the compressor.
what is the effect of higher condenser water temperature have on refrigeration equipment
depending on the temperatures the higher the temps the higher the pressure in the system. I would say you are okay as long as you stay with the range of specs as set by the manufacturer. I’m sure you will lose some efficiency but if the temps get too high you will have serious issues. The condenser does the job of removing heat and I am assuming you are talking about a chiller since you mentioned water in the comment. If the refrigerant temperature is 110 degrees and the condenser water temperature is 105 degrees you aren’t removing that much heat but if the water temperature were 90 degrees then you will be removing much more heat. You would have to run some efficiency curve experiments to see what the effect is on energy use and cooling affect of the equipment based on the condenser water temperatures from one temperature variable to the next. If you have the proper controls in the system you could set up trend charts to get this information otherwise it would have to be done manually.
how would you explain blowing out on a 2004 residential train unit . it blew out one of the compressor terminals and put a hole in the condenser . just before it happened it was locking up .
I can only guess but the compressor likely had serious mechanical issues which caused it to run very hot and that created an electrical problem. Unless you cut the compressor open and do a forensic examination you will not know the root cause of the failure. Typically that is time consumer and can be expensive. I would flush the system to get any residual oil out of the line set and evaporator/condenser and replace the compressor provided the unit is less than 10 years old and has been well maintained. You can repair aluminum in the Trane condenser just find an aluminum solder repair kit. If it is an R-22 unit or is has not been well maintained then I would replace the entire condenser and evaporator (possibly the air handler also (depending)) along with the line set.
The evaporator blower motor on my central AC failed and the system continued to run in 85 degree plus weather for over 24 hours before I discovered the problem. We replaced the blower motor and the compressor unit, although still functioning, is now making a lot more noise than it did before the blower motor failed. Is it likely that the compressor was damaged by running without the blower motor?
Yes and it really depends on the type of compressor you have will depend on if it can possibly survive. A scroll compressor can take liquid slugging far better than other compressors. Without airflow across the evaporator coil you likely had liquid refrigerant make it to the compressor it damaged the compressor in some way. A good refrigeration technician can make a diagnostic check for you and determine how bad it is. Liquid does not compress and when it makes its way into a compressor usually some type of mechanical damage can occur.