t/s by replacing parts? - need help

[OldGray320i]

Good evening.

Question, I had my evaporator coil replaced recently, and since the installation of the new unit, it does not cool in higher heat (I'm in Tucson, AZ). Evening comes, temp drops a bit, and unit will cool.

AC repair dude is the troubleshoot by replacing parts type, and it obviously has not worked (he replaced contactor and t-stat). Now he's recommending a new compressor . I don't want to spend $ on replacement parts to find it still doesn't work.

My question is are the new evap coil and the condensor now mis-matched, causing problems?

The new coil is a Rheem rcfa hm3617ac, 550psi. The compressor is the originally installed RUUD uafd 036jas (1991), best I can tell it's a 3 ton unit, with specs on the id platee as follows: Dsn pressure H, 300 psig, Dsn pressure L 150psi.

Best I've been able to gather AC operates off of pressure differentials in the coil and compressor, and insufficient flow may keep the system from functioning properly.

Help!

Thanks.

Bob.

[jpsmith1cm]

You need to fire your technician.

If the company has no one better, then you need to fire the contractor.

[OldGray320i]

You need to fire your technician.

If the company has no one better, then you need to fire the contractor.

Good man, this I know. However, are my systems mismatched - if they are, then I get to fight with the contractor (the owner is the t/s guy... Nobody I knew had a good recommendation...).

If they are not, I get to pop $ for a new compressor....

2nd opinion call is upcoming, just hoping to get a head start....

Any help is appreciated.

Thanks.

[jpsmith1cm]

Good man, this I know. However, are my systems mismatched - if they are, then I get to fight with the contractor (the owner is the t/s guy... Nobody I knew had a good recommendation...).

If they are not, I get to pop $ for a new compressor....

2nd opinion call is upcoming, just hoping to get a head start....

Any help is appreciated.

Thanks.

Sorry, I don't know a whole lot about matching systems. Troubleshooting is another thing. Someone else should be along shortly to help you on the match-up.

If the unit cools, then the compressor works. Yes, there could be things wrong with it, but given what you have described, I wouldn't point a finger at any of the three solutions that you have been sold.

[HVACJOEK]

Why did they say you needed a new coil?:cool:

[grgas77]

He probably did not recharge the system correctly. Or "wild guess here" your old coil was the type that had a TXV located in the coil case, and the new coil might need to have a TXV installed by the tech. A TXV is a device the meters the flow of refrigerant to the evap coil.

[OldGray320i]

Why did they say you needed a new coil?:cool:

That one was apparent to the naked eye - rusted out, water/condensation leaking everywhere.

Unit cooled just fine (probably not for long in that condition).

New condition of not kicking on in higher heat conditions after the new unit intalled. The only thing I know (or think I do) is that flow rates determine cooling operation, and that outside temperature can affect the pressure or flow rate needed to draw the refrigerant in to the tubes.

I was thinking higher capacity means a larger area (550psi), thus to push enough air through the evap coil to the compressor (300psig) meant not enough volume/pressure moving through the coil, and that's even if I understand the theory correctly. And so my question.

Dude said there was enough refrigerant coming out of the unit to cool, unit cycles on and off at the t-stat. Condition seems to happen only with t-stat set at 85 on hot (100+ F) days. Prior settings at cooler temps (80) kept unit running even on the hot days.

If anybody knows a good troubleshoot guy in Tucson, I'm all ears.

Thanks for the inputs, much appreciated.

[OldGray320i]

He probably did not recharge the system correctly. Or "wild guess here" your old coil was the type that had a TXV located in the coil case, and the new coil might need to have a TXV installed by the tech. A TXV is a device the meters the flow of refrigerant to the evap coil.

I'll ask the old dude and run it by 2nd opinion tech.

Just irritates me that I have to pay another $ or $ trip charge on top of the new unit/service charges the first dude charged.

Again, thanks for the inputs.

Much appreciated.

[andserco]

need to verify the specs on the replacement coil....

[HVACJOEK]

There are some good Tucson guys on here they will find you, now those pressures you read from the tag only tell the design test pressures,the old one has a lower test 300 psi because refrigerants in use at the time of manufacture didn't require the higher 550 Psi that some of the newer refrigerants today need ( R410A), and from the coil info you listed seems like a 36000 btu or 3 ton coil was replace with the same. You could have a problem with the compressor but more then likely it just need to be charged properly.:cool:

[joemach]

You say that the unit is not kicking on in the higher heat. Could possibly be an overcharge and the unit is kicking off on high pressure limit. Don't quote me on all this as I am not there and have not put my gages on your system. If you have a competent technician come out to look at it, I am sure he will figure it out.

Hope you can find someone in your area on this board, as there are really some true professionals here.

If it is a refrigerant charge problem, I would send the bill to the guy who installed the coil.

HTH

[OldGray320i]

Cool beans then, looks like my initial question(s) is(are) answered.

I'll wait for those Tucson guys to post up and give them a call.

Just lamenting to my car guy that those who can t/s well are like gold. Easy life if you know where they are, be they doctors, car repair, or HVAC. Life is painful otherwise.

Appreciate all who've posted - thanks for taking the time to check it out and post up. Again, much appreciated.

Bob.

[OldGray320i]

You say that the unit is not kicking on in the higher heat. Could possibly be an overcharge and the unit is kicking off on high pressure limit. Don't quote me on all this as I am not there and have not put my gages on your system. If you have a competent technician come out to look at it, I am sure he will figure it out.

Hope you can find someone in your area on this board, as there are really some true professionals here.

If it is a refrigerant charge problem, I would send the bill to the guy who installed the coil.

HTH

Each idea y'all post will be asked of the 2nd opinion dude (sure hope a Tucson guy pops on here...).

If y'all run across them on other threads, please do have them check this one. I'd really like to find a good HVAC guy. Downstairs unit is 18 years old too, and if/when it goes, I'd like to avoid this hassle.

Thanks gents.

[riderman]

[QUOTE=jpsmith1cm;4066282]You need to fire your technician.

[catmanacman]

Good man, this I know. However, are my systems mismatched - if they are, then I get to fight with the contractor (the owner is the t/s guy... Nobody I knew had a good recommendation...).

If they are not, I get to pop $ for a new compressor....

2nd opinion call is upcoming, just hoping to get a head start....

Any help is appreciated.

Thanks.

if nobody had a good recommendation why did you use him also i would not put a compressor in a 1991 unit , probably needs a start kit

[beenthere]

Questions and discussions pertaining to HVAC for the home. No pricing, no DIY, please read Site Rules (http://hvac-talk.com/vbb/showthread.php?threadid=1241) Thank You.

[HVACJOEK]

http://www.acfixr.com/


:cool:

[the dangling wrangler]

Like that's gonna be up there a long time.

Ya' gotta pay for that.

[bmathews]

The old failed mix and match. It happens a lot. My advice would be to match a condenser to the coil. Don't replace the compressor on the old beater, that would be ridiculous and will only save a few $$$. If you have a recip compressor on the old unit and a TXV on the new coil. During the heat of the day when the pressure inside the system rises, the compressor doesn't have enough cajones to start. A hard start kit will probably fix this. And make sure it isn't overcharged.

[OldGray320i]

http://www.acfixr.com/


:cool:

I'll call him up. Per chance is he a fellow on the board?

Thanks much.

[OldGray320i]

if nobody had a good recommendation why did you use him ...

100+ days, all the bedrooms upstairs (the rusted out leaking evap coil...). Needed to do something, they could come out.

ROC seemed to check out (15 years in business, 1 resolved complaint - several that I called had same...).

[OldGray320i]

..., no DIY, please read Site Rules (http://hvac-talk.com/vbb/showthread.php?threadid=1241) Thank You.

Plead mercy of the court. Not trying to fix myself (no tools, and as my posts indicate, no knowledge!), just trying to be a bit educated about what to ask, and all the fellas on the board have been quite helpful.

Very much appreciate the time that all have taken to help in that process.

T-stat set to keep air at 80 today, everything functions (compressor kicks on, air cools, etc...). With all I've tried to learn reading on basic theory, and from what y'all have posted I've got lots of questions to ask.

I'll give the acfixer guy a shout and see what the 2nd opinion says, and I'll be sure to post up what the issue was.

Thanks again

[OldGray320i]

Good afternoon gentlemen.

Said I'd post up on what the fix was - almost forgot!

Found a guy here in Tucson, BMS H&C - put a hard start kit on it, life has been good ever since.

I appreciate the schoolin' y'all gave, kept me from buying into a song & dance about a new compressor.

Cheers!

[jpsmith1cm]

Glad we could be of assistance.

Most of us are quite willing to assist a home owner with advice whenever possible.

We also dislike techs who do shoddy work.

Remember the company who fixed it and reward them with referrals and continued patronage.

[OldGray320i]

Already gave his card to my car repair guy - and he sees more bodies in need of help than I do, maybe some who also need home hvac repair as well as car fixes.

And he'll definately be doing any (hopefully not needed soon) future repairs.

Thanks again all.