Trane 2 ton package unit not cooling efficiently

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  #1  
Old 07-11-12, 07:53 PM
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Trane 2 ton package unit not cooling efficiently

I have a trane 2.5 ton package unit that is not cooling efficiently. The temperature differential between the air at the house intake vent and one of the output vents is only 10 degrees cooler. I am expecting around 15 degrees. We cleaned the evaporator and condensor coils with AC coil cleaner and got a little bit of improvement. Also, replaced the filter. It is 85 degrees outside. I am thinking the compressor is working.

Maybe it is a bit low on coolant ? This unit is an R-22 unit (tch024c100a).

Any suggestions on how I can best tell what the problem is and whether coolant is low for this unit ?

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Last edited by hvactechfw; 07-11-12 at 08:30 PM. Reason: removed pressure info.
  #2  
Old 07-11-12, 08:26 PM
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I don't think we can teach you how to do freon work here(against the rule). But Did you hand touch the copper pipes, Is the large one ice cold, small one a little warm ?
 
  #3  
Old 07-12-12, 06:00 AM
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I wanted to know what the technician looks for on this. The last person that came out said I need to spend $4000 on a new unit. It is an older unit, but cooling only 10 degrees instead of desired 15. I can't believe a full replacement is necessary, but I do not know enough about the diagnosing this type of problem to challenge the conclusion. My guess is that there is just a small leak in the evaporator coil.

If I ask out another technician to review the unit, what should I expect a good technician to do for this type of problem ? I read that the technician should check the superheat for the unit to determine whether fully charged. However, another AC person I talked to said this not a reliable way to charge this type of unit.

If it is an accurate way to check, then I would expect the technician to be able to tell me the supercharge is low indicating coolant leakage and isolate where the leak was occurring. Once leak was properly repaired, they should be able to recharge properly using the superheat and pressures to indicate how much to add.

Is this correct ? I don't want to spend $4000 on something that could be a simpler repair.

Also, are there any third-party leak sealants that are known to work well that it would be reasonable to ask the technician to use if the leak is small?
 
  #4  
Old 07-12-12, 07:10 AM
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You are correct, if there is a leak, that must be fixed first. Usually they use superheat and subcool to check the system. if you don't trust the AC tech, go get another one, you saw the NBC sting post, did you. I don't blame you, better to get another opinion. by the way, what is the pipe temp ?? (and Never use leak sealent, you really need that $4000, may be more, if you do)
 
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Old 07-12-12, 11:23 AM
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I wanted to know what the technician looks for on this. The last person that came out said I need to spend $4000 on a new unit. It is an older unit, but cooling only 10 degrees instead of desired 15. (14 to 21-F depending on humidity& temperature conditions indoors.)

I can't believe a full replacement is necessary, but I do not know enough about the diagnosing this type of problem to challenge the conclusion. My guess is that there is just a small leak in the evaporator coil.
I will be writing about what happens with this post on my two websites, on Twitter & Facebook & on my Blogs.

Of course, I have the federal licenses to handle refrigerants; however, listing pressures so that we can tell the A/C user if his system appears to be low on refrigerant does not motivate or promote user's to violate a federal law for which there is a huge fine.

They will violate or obey the law depending on their own ethical character for which we are NOT in any way responsible or liable for. We always warn them to never mess with the refrigerant systems!

There are far too many rip-off artists that will tell a user that the system is leaking when it's not leaking at all.

Some will do anything to make a big money making sale of equipment; the Today Show videoed six of the small-fries.

Equipment owners need education in all areas where they can be easily riped-off; limiting actual performance data simply helps the crooks defraud them!

Below is a simple & totally safe & easy collection of temperatures & indoor humidity for an experts' analysis of your systems performance.

Performance Data Collection Best Time to collect data, Late afternoon around 4-pm:

1) Helpful, Tonnage of Unit or outdoor condenser model number: ________
2) Important, TXV or, orifice metering device? _______
--------
3) Outdoor condenser's discharge-air-temperature _____
4) Out-Door air temperature: _______
5) Condenser air Temp -split _____
6) Need the percent of humidity - away from supply air outlets ______
7) Indoor Return Air Temperature ____ Supply Air Temperature ____
--- Need the above data for system performance analysis

User's come to these forums for help if we tell them they can't work with us to help them prevent rip-offs because, they might violate some law then, you might as well close this forum all together because it will be of little help to them.

Elsewhere, we have as high as 600 guests at one time visiting our forums because we allow pressures to be listed & allow user's to to collect simple safe information necessary to help them realize how their systems are performing.

Consumer customer's need to be informed & educated so they can protect themselves against those who prey on them due to their lack of knowledge.

If you censor this post using far-reaching reasoning I may never post here again...This should never be titled a DIY forum; you obviously really don't want them to do anything!
 

Last edited by HVAC RETIRED; 07-12-12 at 11:52 AM.
  #6  
Old 07-12-12, 01:07 PM
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Is there a way to measure the copper pipe temps accurately without spending a fortune on a Field Piece ? I tried a simple temp gauge but not too accurate. It worked for testing input/output temps on the air ducts going into and out of the AC, but not for the pipe. Maybe there is a simple way like strapping the tip of the temp gauge with the non-sticky side of some aluminum ducting tape to transfer the heat for an accurate reading or some other trick. Or maybe there is a less expensive mechanical gauge that works.

Anyways, just by touch, the pipe is cold going into the evaporator and a little less cold coming out. Also, I am getting heat coming off of the condensor so it is extracting heat. So it is working, but just not to the level of efficiency needed. The air in the nearest output duct (less than fifteen feet from the AC) is only 10 degrees cooler than the air going into the input duct. This is Florida, so humidity is high, so I would expect around 15 degrees of cooling since some of the energy is going to dehumidifying the air.

The coils are nice and shiny now that I cleaned them with the AC coil cleaner, so that is not the issue.


Thanks again for the help. I will call back a different technician tomorrow, but want to make sure I understand enough about the system that I do not get ripped off, especially when we are talking $4000 for a replacement AC that seems to only have a slight leak problem in one of the coils.
 
  #7  
Old 07-12-12, 02:04 PM
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If your large pipe feels cold (ice cold, and wet, I hope), and small pipe less cold (little warm I hope), then your AC may be fine. Don't worry about the pipe temp now, it won't help you much without all other gaged information. when you call the tech in, they will have all those numbers. Now check Condenser air blow out temp, it should be 10-12 degrees higher then surrounding air temp at least. If everything OK, then you need to find the delta t at the coil (right before the evaporator coil and after evaporator coil to eliminate duct related problem.) 18-20 degrees will be good. If delta T at coil is OK, then you need to check the ducts to make sure you don't lose cooling in there.... one step a time.. you will find your problem.
 
 

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