Air con compressor unit very hot???

Hey there,

A week ago, one of my system 3 air con broke down, so I arranged for an air con guy to come take a look.

Today, He examined the air con compressor and said the capacity burst, so he exchanged a new one for US$100.

Before he left, he commented my air con system is old - 9 years and needed a full overhaul. Most importantly, he said the compressor unit is very hot, so the parts must be working very hard, and it will spoil soon.

I find his remarks troubling as it is bizarre a machine can ‘overwork’? Couldn’t he just replace the faulty part that cools down the compressor? He said the new capacitor is inclined to blow again under such conditions.

Please share your insights and experience, should I get another guy to look at the compressor again, maybe replace the cooling unit or whatever faulty?


All machinery either industrial, commercial, or residential needs to be maintained and overhauled on a routine basis or indeed it will break down and be in need of expensive repair.

Such odd expressions.

system 3 air con
the capacity burst
it will spoil soon

OK, you mean the capacitor burst and was replaced for $100 (US, implying you are a USAian).

OK, in an air conditioner the compressor gets hot. Ideal gas law and such. As the pressure goes up, so does the temperature.

If the condensation coils (the ones that are usually outside) are dirty, it will cause the compressor to run hotter, making it work harder. Typically, these coils should be cleaned every year or two to make sure they do not cause a problem. Perhaps this is what the technician meant, your air conditioner needs to be cleaned.

A machine is designed for certain run times. Some are designed to run continuously. An air compressor is designed to run till the reservoir tank is filled to the proper pressure. Then the compressor stops for quite a while and cools down, till it needs to start again. It is designed cheaply enough to run and rest, for those time periods.
If it is leaking around the pistons, it will take longer to reach pressure, if it even can. If demand is too high, it will run too long. When worn, lubrication can be failing, causing even more heat.
So if your compressor is too old, it will have a few problems that will lead to overheating.

I suppose there are compressors designed to take continuous running. But you would have to pay a lot more for one. It would also fail after some time though.

^^^ What excavating said.

In addition: The capacitors (you’ll have another one on the air handler unit) can fail and it doesn’t mean something else is wrong. Capacitors get old and just stop working. My system is 17 years old and I’ve had to replace the air handler cap twice, although the compressor cap is still original.

there are no parts in a compressor to replace. if it dies it dies. Servicing would include proper amount of Freon and proper cleaning of the heat exchanger cooling fins. if the compressor dies then make sure the lines of blown out to ensure metal shards don’t circulate after the new compressor is installed.

I had the compressor replaced on my AC over 20 years ago. It’s running just fine.

Your miss use of words leaves us a little confused and not sure.
9 years old may not be new but it is not old.
Did he say overhaul or major service work?
Small household air conditioning compressors are not overhauled normally. If the compressor is at fault it is replaced, that is a major repair.

If the condensing coils are dirty and damaged then they need to be cleaned up. If the coils are damaged too much they will need to be replaced. And that is again a major repair and both the condensing coils and compressor (condensing unit)should be replaced.

If you decide to replaced the condensing unit get 3 separate bids from 3 separate contractors. Do not necessary go with the cheapest one look at the bids and compare the work being done.

Thanks everyone for the insight!!

He was actually here to clean the air cons. He didn’t say it was dirty - he said the equipment was old and overheated easily - and suggested to change the WHOLE system.

That’s why I thought maybe he was dishonest and just wanted to earn more money instead of a simple clean or lubricant or replacing parts - which at most just the compressor.

Should I get another technician to look at it? I doubt he cleaned the condensation coils, though he did open the compressor to check. I would be annoyed as he could have cleaned and charged me for the cleaning, or he actually don’t know how…

Oh yes, he suggested replacing the ENTIRE system - which meant pulling out all the cables and links. That’s why I was so disturbed after his advice and came here for help. It sounded very unusual. His reasoning was that the condenser is getting heated too quickly. Also the model of the condenser is too old.

He didn’t clean the condenser though. Or he did but did not say…

We use British English here - hehe

Old or new, abnormal internal temperatures can be from a loss of refrigerant or other issue besides being “worn out”.

It is quite common to need to clean the outside (condenser) coils. If you can’t remember the last time they were cleaned, then they’re overdue. This will involve getting access to the coils by removing any covers, etc. and then using a coil cleaner like Coil-Rite to get rid of any gunk, followed by a coil comb if many of the fins are bent over, followed by removing any accumulated crud in the base pan at the bottom of the coil.

The coolant system is sealed at the factory for window units or at the time of installation for central and mini-split systems. The bottom of the compressor contains a pool of lightweight oil. There’s no way to add oil without opening the system, which is a pain on an older unit for reasons I’ll get into below.

Is this a window unit? If so, then it is normal to replace the whole unit if something in the sealed system goes wrong. But that is an infrequent occurrence (as you can see by the long warranty period for the sealed part of the unit).

If it is a central or mini-split system, it is usually more cost-effective to replace damaged components. However, there are some issues to be considered:

  1. As this is an older system, the refrigerant used (R-something) may no longer be available. Older ones have been banned for being ozone-depleting substances. Changing the refrigerant type will involve (at a minimum) carefully flushing the entire coolant loop. If it is one of the older compounds and lost its charge it can be a real pain to obtain material to recharge it, and it can get quite expensive as well, although there are “retrofit” refrigerants available with varying levels of compatibility. If the unit has lost its charge it also needs to be pressure-tested with an inert gas first, as well as possibly replacing the dryer unit.

  2. If there is a catastrophic compressor failure the lines can become contaminated and depending on how long the run is, it could possibly end up being cheaper to just replace them. For example, a condenser just on the other side of a wall in a mini-split system. And if the installer replaces both the inside and outside units and re-uses the lines, they might well describe it verbally as “replacing the whole system”, though I would hope the written quotation has some additional specifics.