a/c unit failures

[jackhipp]

:gah:I have a Lennox 12ACB42(3 1/2 ton) split central a/c unit that from time to time quits cooling. This has happened 4 times this summer in Plano, TX where it's been real hot. Anyway, With each cooling shutdown I have done the following:
Turn the compressor off at the thermostat leaving fan running
I have hosed down the unit
I waited about 30 min's and turned it back on
In each case it started cooling again - sometimes 6 weeks between failures?
I have had the unit checked on 2 seperate occasions and everything checks out? Freon full - Compressor running OK
However the last time I had it checked the technician noticed that the compressor had some high head pressure readings and he thought it was slowly dieing.
Does this sound right???????
Thanks

[HVACTechNC]

The compressor is locking out in thermal overload. Could be one of a few problems. Could be a bad compressor thermal overload switch, if nothing else is truely wrong. That would be sad as it would require replacing the compressor. Possibly a restriction in the refrigerant line, clogged filter dryer or a kink in the line. Dirty condenser coil would probably be the easiest possibility to find and repair. A measurement of superheat and subcooling would be helpful in determining if there is a restriction in refrigerant flow, and narrow down where it might be.

[second opinion]

Look at your service ticket and see if he entered pressures and temperatures. To say you have high head pressure without telling you why is like the doctor telling you that you are running a fever and slowly dieng.

[jackhipp]

Thanks - I will see if I can locate the pressure readings

[32ndmm]

could be txv

[lonestarheir]

My first thought was dirty filter just because I see that so much... But have to agree with the rest of the posts above as well...

[timebuilder]

It sounds like a maintenance issue.

Have the tech clean the indoor and outdoor units. This uses professional chemicals and should not be attempted by a homeowner.

[jackhipp]

Thanks for all responses. Two questions:
1) What about the Capacitor?
2) Are there still 12SEER Units with the old Freon available?
Thanks,
Jack

[jackhipp]

If I install a 13 Seer system that requires the R415A freon, can I use the existing coils???? I have read where this practice is not recommended by all technicians?
Thanks

[NCHeat]

Thanks for all responses. Two questions:
1) What about the Capacitor?
2) Are there still 12SEER Units with the old Freon available?
Thanks,
Jack

sounds as if this has nothing to do with the capacitor and I would not recommend using existing evap. coil with a switch to R-410a. There are dry ship units that can use R-22 in a replacement situation (which this is) and you could use your existing coil for that. The draw back to using your existing coil is that a dry ship unit is marked 13 SEER but with your existing coil you will not get that level of efficiency. 12 SEER units are not manufactured anymore. 13 is the minimum allowed by law. Good Luck

[second opinion]

The capacitor would not cause the problem that you stated.

Yes R22 condensers are still available.

No you should not install just install the outdoor unit.
Did you find your invoice with the diagnostic information on it, and can you post it?

[lonestarheir]

There are Nitrogen Charged R22 units available (Minimum SEER rating manufactured is 13 SEER) for use when replacing just the condenser.

You would need to have a qualified tech check the condition of the capacitor, condenser fan motor

I believe that you are a bit confused... A SYSTEM would include all components inside and out... I believe that you are talking about just replacing the condenser (the outside portion of the system) - If you go to R410a you will need to change the evaporator coil if it is not currently rated for the pressures that R410a runs at. If the evaporator coil has been replaced in the last few years already then it may be possible to install a TXV, run a flush through the system and be ok, but if the coil is more than 5 or 6 years old the is a very good chance that you will need to replace the evaporator coil as well...

Hope this helps...

I would strongly advise you to find a qualified company in your area from the contractors map on this site...

[jackhipp]

Lonestarheir - Are you referring to the Air Filter? We replace that on a monthly basis with a good quality filter.

[jackhipp]

Lonestarheir - Thanks for the information

[lafittejdubb]

Sounds like you just need to call another contractor out. I would recommend having the contractor perform a full assessment on the unit and put that IN WRITING.

Your ticket should have psi's including SH and SC, Voltage and ampere (VA) readings - before and after the contactor for the compressor, and VA readings on motors, evaluate capacitance on the caps (which could cause a motor to overheat, if under), and clean RA box and coils plus replace filter with pleated. BTW, make sure they log all the FLA and capacitance ratings plus the freon type on the sheet so you'll be able to identify what appears out of parameters.

Doing all this, at a minimum, would then give you factual data to work with to evaluate / troubleshoot your potential cause for thermal OL's on your compressor.

Nobody on here is going to able to accurately t/s your problem with the little information you've provided, without taking a shot in the dark! For all we know you could have had a freon leak last summer on a discharge line that leaked a lot of oil out of the compressor causing lack of lubrication. Ultimately, we are all just guessing without data!

[second opinion]

The capacitor would not cause the problem that you stated.

Yes R22 condensers are still available.

No you should not just install the outdoor unit.
Did you find your invoice with the diagnostic information on it, and can you post it?

If you could post more information related to the service call and the equipment it might be possible to help help rather than speculate.

[Kevin O'Neill]

I would avoid the "Good Quality" pleated filters. They are highly restrictive to air flow and can reduce the performance of the system. They may be contributing to your problem.

I would want to test your air flow with instruments to be sure it is adequate before installing a pleat.

I normally see 10% to 20% reduction in measured air flow when going from a fiberglass filter to a pleated filter.

If you have a Variable Speed blower, the pleat is usually OK, but since I don't know your indoor unit model number I can't say.

[cec39466]

In this field we sometimes only get 1 chance or mistake. I hope you kill power to the unit before washing it down. Intermittent problems can be hard to find. They are sometimes costly but cheaper than your life. It's time for a pro.

[Kevin O'Neill]

In this field we sometimes only get 1 chance or mistake. I hope you kill power to the unit before washing it down. Intermittent problems can be hard to find. They are sometimes costly but cheaper than your life. It's time for a pro.

?????

This unit is made to be out in the rain. You do not need to be worried about electrocution unless you open the service panel while you are rinsing the unit.

[udarrell]

There are a lot of things that need to be checked in this situation.

Some causes of compressor overheating are:

Is the Compressor's discharge-line temp above 225-F -find & eliminate the cause
Bad circuitry connections resulting in voltage drops
Bad control contractor points
Is superheat & subcooling within tolerances?


There are more casual reasons & performing all the tests will reveal the cause or multiple causes.

Check the compressor's terminals & use a capacitor tester to verify both compressor & condenser blower motor are performing properly.

Perhaps the condenser blower motor is slowing down...

Is the compressor's oil being properly returned, etc.

[XcelTech]

ohhh no no no. Your system is toasted! It is no good. You are gonna have to throw it all away. The problem you are having is due to freon worms. You get those during the colder months if you forget to change from summer to winter freon. Them worms just love to eat up that summer freon :) lolol

I would suggest if that company has come out twice and can't figure out the problem it is time to talk to a supervisor or change companies. Specially if they are charging you for each call individually at full cost.

Secondly, I would keep your eye on your electric bill and watch the unit to try to find out how long your unit is running. If the unit is running nonstop all day and the temp doesn't keep dropping your unit may not be able to satisfy itself or the circuit is stuck closed. This could be caused by a welded contact along with 80 other things. I would also look into a week timer, ask the technician to find out if that unit has a delay on start timer. If the timer is weak or getting over heated it could be opening the circuit. If he finds it but is not sure it is the problem, it is a very cheap and easy to replace item as a last ditch resort.

Last but not least.........STOP resting the unit. How is the tech suppose to find the issue when the issue is not happening or the unit has been reset and the problem cleared out.

Good Luck!
Scott

[texas cooler]

It would be in your best interest to get a comprehensive check done on your system before accepting the diagnosis that the compressor is slowly dying. There is a reason that the unit keeps shutting off and a complete analysis should uncover the underlying problem as well as a solution. A total check-out should include airflow measurements, electrical measurements, wet and dry bulb readings and temperature measurements. I would not expect any of the $xx.xx lowball "complete" tune up company's checks to cover all this.