evaporator coil restriction?

[yayadogma]

was told i have a clog in refrigerant line in evap coil. can someone see if the diagnostics agree with this? (the tech recommends replacement of the whole air handler unit inside, and says the condenser is old and might as well be replaced too.)

-the AC won't cool condo down past 80F degrees (it is 103 degrees F outside in Texas now!)

-R22 system

-2 ton air handler/evaporator (make: GE, model JPG3607. he said this is a stupidly-designed air handler, an old design used only in apartments and condos where maintenance is usually not performed by the occupants). I think the air handler is original, so from 1981, but not sure.

-900 sq ft condo

-compressor is General Electric, manufactured/installed in 1999

-supposedly, he found the "filter drier" was still installed, said it should have been removed a few days after system installation or service, and might have caused the clog.

-I have noticed that the "popcorn" coating near many of the ceiling air vents is detached and drooping...why? is humidity not being reduced by the air handler? i forgot to point this out to the tech...

-compressor unit seems clean, without dust and debris.

-evap coil fins probably have some dirt from old tenants using cheap filters, but he said the design is such that they can't really be cleaned effectively, nor can you really treat the condensate drain line with bleach. he also said can't replace just the evap coil, as it is too old and the part would not be available.

-suction pressure: 78
-Head pressure: 275
-ODT: 99
-Subcooling: 130
-indoor amps: 2.6
-outdoor amps: 18.1
-Super Heat: 38

I can say that the cover to the indoor air handler was not quite re-attached correctly at the time he did the readings on the compressor outside (it was a little bit ajar). He said it was good enough to take the readings, but could this have made his readings invalid? The AC unit had not been used during the day that day, so the indoor temp was probably 90 degrees when he arrived. He let the system run for maybe 10 minute before he did the readings on the compressor...

he wants to put in a Puron Carrier condenser, but says the only air handler inside unit that will work with the configuration is a Goodman model. Said the best SEER that will be possible (due the the above constraint, I guess) is 13. offers 10 yr warranty on carrier, 5 yrs on Goodman, 1 year on labor.

does this diagnosis and solution seem right to anyone who understands this? I've tried reading about it, but makes my head spin. i don't have a lot of spare money, so i'd like to make sure this is a good diagnosis, and there isn't a cheaper repair, rather than replacement.

thank you.

[pwg11386]

i'd be a bit reluctant to do business with this technician. Never mix brands between indoor and outdoor unit. I would try to find someone who is confident that they can fit matching equipment in the space.

Hard to say what the problem is with your evap coil. I feel that the head pressure would be higher if there is a restriction in the evap, especially at 99 degrees outside temp. also the suction pressure doesnt really characterize an evap restriction.
Difficult to say though since im not there.

Where is the "filter drier" located? on the small refrigerant line or on the larger insulated line? just wondering if its a liquid line drier or a suction filter

[jim147]

I'd want to recheck that subcooling if i was writing down those numbers.

jim

[yayadogma]

Where is the "filter drier" located? on the small refrigerant line or on the larger insulated line? just wondering if its a liquid line drier or a suction filter

I'm 99% sure he called it a liquid line drier. It was located outside at the compressor somewhere (I was not out there at the time.) He said he removed it...

[yayadogma]

I'd want to recheck that subcooling if i was writing down those numbers.

Ah, I see--he wrote 13°, not 130. I guess it has been too long for me to edit my first post. If a mod or admin sees this, could you correct it in the original? Thanks.

[NY2GA01]

-supposedly, he found the "filter drier" was still installed, said it should have been removed a few days after system installation or service, and might have caused the clog..


I have been to a few jobs where the suction line filter drier was still attached, from what you said it sounds like a suction line drier.

What kind of system are we talking about? Did I miss it?? Do you have a aquatherm system? That is the kind of system I have in my condo and it's found in a lot of apartments in atl (most of, or all of post properties use aquatherm systems). I have a first company air handler and an air quest outdoor unit. With this kind of system it's common to find mixed indoor and outdoor units.


Are we talking about R22 as a replacement unit, or are you talking about R 410 a?

[yayadogma]

What kind of system are we talking about? Did I miss it?? Do you have a aquatherm system?

Are we talking about R22 as a replacement unit, or are you talking about R 410 a?

I do not think it is aquatherm, after reading a little online about what aquatherm is. My hot water heater is completely separate. My AC and central (air) heater are electric. The evap coil is lowest, above that is the blower, and above that is the air heater. (The heater is not below the evap coil as I have seen it in diagrams of how other air handlers work.) My AC refrigerant lines are copper pipes, not polypropylene like it says aquatherm uses. The manufacturer of the current equipment for both the air handler and the compressor is GE (model # is listed in first post).

For the replacement, he wants to do R410a (aka Puron).

So do you still think mismatched brands is OK for me, or it is hard to tell? Thanks.

[udarrell]

When outdoor temp is 99F super-heat should never be 38.

If it is a fixed orifice, at 80F dry bulb & 67F wet bulb, around 50% Relative Humidity, the super-heat should be at 12-F; NOT 38F.

Even with a TXV metering device the supper heat will be between 10 & 15F, depending on its setting...

The system has problems that need to be dealt with & a restriction could be one of them

The head pressure at 275-psig is 124F condensing temp., - 99F OAT is a 25F condenser temp-split. That could be normal for say an 8 to 9-seer condenser.

If the condenser was installed in 1999, it could be a 10-seer or higher; then condenser temp-split is too high; it could be drawing hot Attic Return Air into the E-Coil.

What is the indoor humidity level?

I would check to make certain there is no hot air being sucked into the return Air ducting. Make sure duct system is well sealed, then check air flow CFM.

From here; this appears to be a simple restriction or hot air drawn into Return, & perhaps some other minor issues...:.02:

[yayadogma]

The head pressure at 275-psig is 124F condensing temp., - 99F OAT is a 25F condenser temp-split. That could be normal for say an 8 to 9-seer condenser.
The tech said the current system is probably SEER 8.


What is the indoor humidity level?
According to Wunderground, the outdoor humidity at the time he came was 31%. I don't have a hygrometer, but my doors and windows had been open before he came, so maybe it was close to that.


I would check to make certain there is no hot air being sucked into the return Air ducting. Make sure duct system is well sealed, then check air flow CFM.
There is no return ducting: the air handler is in the living room on the first floor, drawing directly into the air handler from the living room air. I know the cold air ducting may be kinda funky...for one thing, there is a floor vent in the second floor office that is carpeted over.


From here; this appears to be a simple restriction or hot air drawn into Return, & perhaps some other minor issues...:.02:
Since it is not the air return...You say maybe a "simple" restriction. You mean it can be treated without replacing the air handler? The tech said the evap coil can't be replaced (no spare parts avail), so handler must be replaced.

[NY2GA01]

For the replacement, he wants to do R410a (aka Puron).

So do you still think mismatched brands is OK for me, or it is hard to tell? Thanks.

Can I ask you a question.. If your not so comfortable about the company you hired for what ever reason, why don't you call another company and get a second, or even a third opinion?

If you were to call a company and tell them you got a price quote for a new system and you want a second, or third price quote, I bet they would come out and give you an estimate for free.

What stands out to me is the fact he is pushing the puron unit on you, by saying they offer a 10 year warranty and Goodman offers a 5 year warranty on a R 410 a unit sounds like he's pushing it.

They only Goodman unit that I know that has a 5 year warranty is the R 22 dry units. I believe that is a standard across the board, so for it to be on a R 410 A Goodman unit sounds strange.

As a rule of thumb it's always best to have matching units.

[martin&sonsa/c]

did you say that he removed the liquid line drier? so he pumped down the system cut it loose and then rewelded the lineset? everything about this situation sounds strange to me. if he is going to install a goodman inside unit then why not a goodman outside unit???? where at in texas r you?

[udarrell]

The tech said the current system is probably SEER 8.
"-compressor is General Electric, manufactured/installed in 1999"
If you meant the condenser, then it should be a 10-SEER or higher.
Maybe it's to his replacement advantage if he guesses a lower SEER.(?)

According to Wunderground, the outdoor humidity at the time he came was 31%. I don't have a hygrometer, but my doors and windows had been open before he came, so maybe it was close to that.

If the humidity is only 31% then; 25F is too high a condenser split for a +10-seer; it must be drawing hot air from somewhere; maybe the covered return is leaking RA into its duct?

There is no return ducting: the air handler is in the living room on the first floor, drawing directly into the air handler from the living room air. I know the cold air ducting may be kinda funky...for one thing, there is a floor vent in the second floor office that is carpeted over.


Since it is not the air return...You say maybe a "simple" restriction. You mean it can be treated without replacing the air handler? Maybe; also could be a hot source RA airflow problem; guessing from here!
The tech said the evap coil can't be replaced (no spare parts avail), so handler must be replaced.
May NOT need to replace evaporator coil...

A restriction should reduce the condenser temp-split NOT increase it.
Since super-heat & condenser temp-split are both too high there appears to be an obvious heat-overload on the evaporator coil.

If it were low on refrigerant the condenser split should be lower not higher.

What is the indoor SA RA temp-split?

Get yourself a cheap hygrometer at a hardware store.

[yayadogma]

What is the indoor SA RA temp-split?
The indoor temp differential (SA-RA) seems to be 15.2 degrees F.

[udarrell]

The indoor temp differential (SA-RA) seems to be 15.2 degrees F.

"If" the humidity is only 31% & the airflow is at around 400-CFM per/ton of cooling, with that low a humidity level the indoor temp-split should be over 20F.

The airflow differential does not affect the indoor temp-split, much at all, compared to the humidity differential.

Can you check the Return Air near the unit to see if its temp is much higher than the Indoor Air Return temp?

It has a way too high super-heat, - coupled with too high a condenser temp-split; you should know where the problems may exist.

Why the apparent extra heatload on the evaporator coil & the condenser, huh... :pop:

[jpsmith1cm]

everythingisdumb

This is the Ask Our Pro's forum. In order to post a response here, you must have verified qualifications and have been approved by the AOP Committee. You may ask a question by starting a new thread.

You can find the rules for posting and qualifications here (http://hvac-talk.com/vbb/showthread.php?t=957002).

Additional infractions may result in loss of posting privileges.

Your post has been deleted.

[catmanacman]

A 2 ton compressor drawing 18.1 wow

[udarrell]

At 85-F indoor temp & around 31% relative humidity the indoor temp split should be around 24 or 25-F & not 15.2-F with a 38-F superheat indicating an overload combined with a high indoor temp load on cooling coil; with a flow rater could have around 23 to 25-F superheat with those apparent conditions.

Even though the RA is drawn into a chamber below the air handler too many don't have the dry wall stud area around the chamber properly sealed & it draws hot air from between the studs from an attic or other super heated hot area.

A system that is way over-charged has very little condenser area to dissipate the heat, which will also run the head pressure up & run discharge line temp up.

The temperature of the compressor discharge line should be taken & should not be above 225-F.

The 18.1 condenser amps is a ton too high; indicating overload issues!
Also indicator of hot gas discharge LINE RESTRICTION!

I'd have to be there to run all the necessary verifying tests...

[wahoo]

I'd recommend a "second opinion" also as some of this makes no sense to me. Freon pressures don't indicate a plugged coil.

[udarrell]

All those indicator numbers could be indicative of a somewhat restricted compressor discharge line; however I agree with wahoo, it seems from here, more like a heat-overload through the evaporator coil.

I'd measure the temperature & humidity level of the Return-Air "just before it goes through the indoor cooling coil."

What is the CFM airflow number? It also ought to always be checked...

Find someone that can do a more complete job of troubleshooting the system. It can't be fixed until they find the actual cause(s) of the problem...