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Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 5550
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Amana prestige 5 ton ac unit intermittently blowing warm and

Customer Question

Amana prestige 5 ton ac unit intermittently blowing warm and cold (normally warm), 105 degrees out, blower under house and blower on condenser work great, freon lines warm to touch. Unit likes to work properly in cool morning. Once temps go up...nothing but warm air. Unit about 8 years old.
Submitted: 1 year ago.
Category: HVAC
Expert:  Phil replied 1 year ago.
Welcome to Just Answer!.

I will stay with you until the situation resolves. I hold questions open after positive ratings to allow for unlimited follow up.

I need some details on how the system is laid out. Is there two copper tubes going from the unit under the house, and a unit sitting outside the house.?

Is one of the tubes about the diameter of a ball point pen, and other tube close to an inch in diameter?

Tell me if you have pets in the house or not.

So far it seems like the condenser coil on the unit that sits outside is clogged with dirt or pet hair... that is common after 8 years, and will allow the system to run and cool properly in the mornings, but not in the hotter afternoons.


Tell me as much as you can about all of those, in detail, we can go from there until the situation resolves.

Phil
Customer: replied 1 year ago.

You are right...condensee sits out on patio, 2 copper lines run into house. large copper line is usually cold


 

Customer: replied 1 year ago.

Not sure if my last post went thru. Unit is outside on patio, 2 copper lines (1 large, 1 small) run into house. it seems for a second or two, the condenser comes on with the fan but goes off just about immediately. i dont know this for sure, just seems like i hear more sound from the unit for the first second or two.

Expert:  Phil replied 1 year ago.
Hello again, I got both messages. I must come and go however answering many questions and doing the research required and typing responses etc.

So far it sounds like a compressor problem... hopefully just a bad run capacitor... those cost about $60... replacement takes a bit of technical ability however.

If you have a clamp around type amp meter and a multi meter can coach you in diagnosing the problem if you are safe around high voltage electricity and safe working on appliances.

If you have the work done and *if its just a bad capacitor, the total charges will be in the $300 to $350 range

Let me know how you want to approach this, and what test equipment you have... you can buy a clamp around type amp meter/ multi meter for $60 at Home Depot or an similar store.

We can go from there until we get the situation resolved.

Phil
Customer: replied 1 year ago.

i just inspected coils and while not much pet hair (do have dogs) there is alot of mud and sludge inside on the base around the compressor. cleaning it out now. coils look pretty clean now after a light hosing.

Customer: replied 1 year ago.

while i am good around high voltages and inside appliances, i dont have a meter with an inductive pickup...just a basic sperry digital model. i think you are right on about the capacitor, they dont seem to last long up here in the desert.

Expert:  Phil replied 1 year ago.
Hello again, does your sperry meter have a capacitance setting on it? If it does you can check the capacitor with that... or you can buy a meter that does. Lacking that a clamp around amp meter will be needed.

OR... you can simply remove it and take it to Grainger Industrial Supply, or Johnstone supply and ask them for a match up and give it a try.

( It is easy to get the wiring wrong when replacing a capacitor... please tell me how many black plastic cups are on the run capacitor that connects to the compressor and I can coach you if you think its necessary..... look for any markings such as Herm, Com and Fan.)

The run capacitors rated at 440 volts will last longer than those rated at 370 volts in the desert.

Let me how you wish to proceed, we can go from there. I recommend that you get a clamp around amp meter though.

CLICK HERE PLEASE

Customer: replied 1 year ago.

Just had serviceman here...thinks compressor is on last leg. it was in thermal shutdown, quite hot. we removed the stunningly thick and insulated cover and its running now. doesnt seem as cool as normal, but it is running. probably in a downcycle, ready for replacement. sincere thanks for the effort, i am pleased.

Customer: replied 1 year ago.

...i find it completely absurd manufacturers like amana would enclose these compressors in such thick and fully enclosing fabric covers. no wonder my compressor was running hot. while i dont doubt its on its way out, it is running continuous right now without that ridiculuous thick cover.

Expert:  Phil replied 1 year ago.

Hello again, those compressors rely entirely on the cold return refrigerant coming back from the cooling coil inside the house to cool the compressor.

They put the insulation around the compressor to reduce the sound from the compressor, it is not common practice though... with the insulation in place the compressor will not cool off on the off cycle as quickly.


The compressor may or may not be on its last legs... generally these fail suddenly like light bulbs.. if it still runs it could keep on running for a few more years.

Here is a list of what causes them to run hot:

_ Dirty condenser coil. dirt between the fins, the coil looks clean but is actually clogged ...at 8 years old I would expect the coil is clogged with dirt, To clean it turn off the power and press a garden hose with your thumb over the end tightly against each square inch of the coil surface.. and watch the water come out black on the other side.

- if the system is a few ounces low on refrigerant it will also run hot.

- There is a much lower chance that the run capacitor is starting to go bad... if you buy an amp meter we can assess that.

 

- Most service men carry an acid test kit, if the oil in the compressor has any acid in it, then the refrigerant drier should be changed. We can discuss what you can do about that yourself later if you are interested.



Meantime clean the condenser coil. let me know how that goes.

 

If you care to rate my service so far positively I will keep the question open without any time limit

Thanks!

Phil

Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 5550
Experience: Retired HVAC/ Electrical & Boiler contractor. Industrial
Phil and 2 other HVAC Specialists are ready to help you
Expert:  Phil replied 1 year ago.
Thanks for the positive rating. Use a garden hose to clean the condenser, with the power to the unit turned OFF, don't get any water on the electrical controls or the fan motor... if you do let them dry out for a few hours.
then run the unit and tell me how it goes, we can proceed from there as necessary.

Phil
Customer: replied 1 year ago.

i did hose those coils nicely today, they are clean. As of a couple days ago (before 100 plus temps, the system was strong). its just amazing today...that even with all his troubleshooting, just taking off the heavy compressor cover and hosing it down for ten minutes...did it start to work. while it is working, not quite as cold as usual...or even 2 days ago. but at least it is running. will keep you posted.

Expert:  Phil replied 1 year ago.
OK, thats a good plan.

but just be sure, just hosing down the condenser if thats all that was done is not sufficient, the water has to be FORCED between the fins, aggressively... virtually all condensers that old will be loaded with dirt deep between the fins and the water will come out black. even though the coil looks clean at the surface.

Stay in touch as needed.

Phil

Customer: replied 1 year ago.

Phil, give me yout thoughts on this... Predictably, my ac compressor did fine thru night and into the cool morning. Then around noon with heat of day, compressor wont engage. Hose compressor down for 5 minutes and it engages. Merely light cool air at first, but the more it runs, gets a bit colder. Fins are spotless also as we discussed. Question is this...do we assume this is a weak compressor or could the compressor have an overly touchy temp sensor for shutdown. I can get a compressor for about 5oo to 7oo online. Whatever the issue is, its in the compressor. The hose gets it going every time.

Expert:  Phil replied 1 year ago.

Hello again, indeed the compressor IS going off on its internal overload.

That could be the result of a compressor problem, or the overload being too sensitive and wearing out. But can also be caused by external forces... such as:

- Low voltage supplied to the unit... (about a 10% chance)
- Motor windings in the process of burning out. (thats why I asked for the amperage
and acid tests of the oil)
- A dirty condenser, with the fins totally clean looking. (but with dirt *deep between
the fins* where it can't be seen. However if that were the case the head
pressure readings would be over 300 psig. if the head pressure is actually
only 115 psig, the condenser is in fact not dirty. )

The statistics on replacement compressors is that they last about half as long as the original compressors because of the acid and contamination produced when replacing them.

I never recommend changing a compressor in a condensing unit that is over 5 years old, and then only if it tests clean for acid...it has acid in it is cheaper in the long run to replace the entire condensing unit.

Working on these is not like working on a car, simple mechanical issues. Its more like a chemistry project... where contaminants can create major problems.

_______

This job needs to be seen by a trained technician in order to get a repair done... the pressure readings given do not align with a suction line that is sweating... so it is quite likely the compressor is good, and that unit is over charged with refrigerant and that there is air in the system causing the head pressure to run very high.

That would cause these problems... if you have not used a vacuum pump to evacuate the system when doing the work you have done, air in the system would be the problem.

These issues must be sorted out first... before you do further work, or you will have problems with what ever you do... air inside the refrigerant circuit, over charged with refrigerant, damage from acid inside the system, and other problems.

The community colleges have training courses on how to work with these systems, those classes take two years for most people about 8 hours a day... some people learn pretty well after a one or two year apprenticeship...

Doing this work without that training can be a problem. If you want to work on your own unit the least you will need is a vacuum pump and a clamp on type amp meter, and a way to insure you are getting good gage readings. Learning to use the pressure temperature chart I linked to will be important in that regard.

Stay in touch as needed.

Phil





Customer: replied 1 year ago.

I should have elaborated... While i will buy the compressor, I will have HVAC professional install. I dont think i ever provided you and pressure readings, but do recall seeing high side pressure around 175-180 and low side i think i recall perhaps 110-120 on the servicemans gauges. Also the serviceman did check the voltages aroumd the unit and gave a prognosis of weak compressor. If I can find a reasonable 5 ton condenser assembly, I would do it. As you would imagine, the quotes for a whole new unit installed are ridiculous. They clearly understand they have me over a barrel...hence the crazy quotes. If the compresser is the faulty part, that will be my replacement focus.

Expert:  Phil replied 1 year ago.
Hello again, be sure they install a new refrigerant filter drier if the compressor is replaced (about the size and shape of a 1 lb can of food with a fitting on each end.).... have them test for acid in the system before the compressor change out, and install an over size filter drier if there is slight acid contamination...

with a damaged compressor the damage does beyond the compressor. It is not just a compressor issue unfortunately as would see in a car... with these systems the compressor and electric motor are welded into a single unit, the oil and refrigerant react under high heat when the compressor gets to hot, and acids are formed, those contaminate the entire system and must be removed entirely if the new compressor is going to last very long.

Historically replacement compressors last about half as long as compressors in the original equipment solely because of these contamination issues.



The thing to remember with the compressor being the faulty part... there is collateral damage. A good technician can avoid much of such damage but not all of it.

Stay in touch as you need to. we can go from there,


Phil

Customer: replied 1 year ago.

Well....things are looking up. I researched system pressure increases with increased in outside temp (significant) and many compressors inability without a hard start capacitor to overcome higher pressures and start....or at least start quickly without dragging. I installed a $10 Supco capacitor and it has started fine so far. Once running, its always done fine. Just wouldnt start on hot days. Ill keep you posted on our progress. In my research, many sources said older AC units typically had start and run capacitors, but the mfrs in their desire to make more money eliminated them.Judging by the huge number of onling posts of folks like me of whom a hard start capacitor remedied their problems...seems like they made a mistake. Funny how my HVAC tech never mentioned this $10 part as a possible solution... :)

 

Expert:  Phil replied 1 year ago.

Hello again, the hard start kit should come with a relay that takes the start capacitor out of the circuit once the compressor is running for 3 seconds.

Adding a start capacitor without the relay can be dangerous... I am surprised you got the kit for $10... retail price is generally a bit over $50. It will be a good idea to check and see if it has that relay.

_______

The older compressors were piston types, the typically required a start capacitor in addition to the run capacitor... the newer compressors, rotary and scroll types require less starting torque, and do not typically need a start capacitor... if they do need a start capacitor that points to low voltage problem or a problem inside the compressor.

 

The start kits are left out not so much to save money, as to eliminate failure modes.. so that motors in the compressors are designed for more torque with out the need for the hard start kit.

 

Many times however a hard start kit will give new life to a compressor.. it is certainly not a bad idea to try it... but be sure it has that relay I mentioned.

 

 



Stay in touch as needed.

Phil




Customer: replied 1 year ago.

It has an integral relay. The unit has been perfect since. Best $10 i've spent. I can see consumers need to be educated. Considering the sales pitch for a very costly new unit (mine only 8 years old) i received from my visiting HVAC tech, and numerous stories from families and friends, it seems the HVAC industry would love all of us to be buying expensive new systems every few years. Thanks again for your correspondence. AC is working well again...

Expert:  Phil replied 1 year ago.
Hello again, there are honest and dishonest people in all businesses, The HVAC business has its share of dishonest or incompetent people... we see it in government and finance too... a veritable epidemic.

People like you who keep their wits about them are about the only ones who have a good chances in those situations... it paid off for you in this case.


Phil

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