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1st RFM/FFR Legacy Winner
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Discussion Starter #1
My home has two units. The one upstairs is not cooling well. The home warranty provided service and the handyman added 1/2 pound of "new R22" a few weeks ago when it was cooler outside. Now that it's hot, the AC is unable to maintain 76 degrees while running all the time. Both AC's are 2001 models.

The filters are clean. I inspected the evaporator "W-shaped coil" and it is not dirty with lent and dust. There seems to be good airflow through the system.
I collected some data today:

86 degrees and 64% humidity outside
Room temp with AC running for 2 hours dropped from 80* to 77.6 * with the thermostat set to 76*

Air coming out of the vents warmed from 62 to 65* over 2 hours
Temp split went dropped 16 to 12* over 2 hours
Room humidity dropped from 58% to 56% over 2 hours
Low pressure return line increased from 42 to 47* over 2 hours
The indoor unit fan speed to wired to HIGH.
Condenser fan air temp is 113*

Seem to me the evaporator is not losing enough heat to the air. What could cause this? I'm going to call for service tomorrow but ti would be helpful to me to discuss this with someone on the forum not trying to sell me a new AC.

PS. Some indoor W-coil pics. These are the sides facing the blower.




The side of the coil:


Thanks
Greg
 

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You can't tell for sure without the gauges on the system while it is running. Sounds like the fluid is low again. There must be a leak.
 

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X2 what Trevor said. If you find any oil residue on any of the tubing there's a good chance you have a leak close by. Even with out that there could be a leak however. Not sure what the shiny look on the tubes in the center of your 4th pic is?
If you had a lack of air flow through the evap coil and everything else was normal your low side line back to the condenser would likely be frosting up from the lack of heat absorption into the Freon.
Any half way decent tech will have a leak detector that would find the problem area. Hope its an easy fix. Good luck.
 

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we recently took apart an evap coil that was probably 20 years old but looked corroded similar to yours. Apart from exterior corrosion we also found corroded pitted buildup inside the tubing that would have affected the flow of refrigerant (Freon in our case) through the evap coil.
I'd start with a new evap coil & try for Al rather than Cu tubing as the latter is also subject to formicary corrosion that has been well documented as reducing evap coil life spans by 50%. (That metallurgical minor I took one summer finally paid off >:))
 

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Discussion Starter #5
Had an AC guy check it and the readings were:

High pressure 325 psi @ 91*
Low pressure 97 psi @ 52*
Return air temp 79*
Chilled air temp 70*
Outdoor temp 89*
Attic temp 137*

He diagnosed either a failed expansion valve or block Freon tubes in evaporater coil. He also said the guy that added the replacement R22 screwed me because it shouldn’t be mixed with real r22 and now we can’t reuse the Freon if we replace the coil or valve. He also said there was no dryer/filter in the liquid line. At 20 years old, it’s time to replace the unit. Repair would be at least $1500.
 

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Ok, what your new guy is saying sounds probable. If the first guy in fact did put something other than R22 in, then that by it self would create problems on top of what ever else is wrong. Do you remember what color the can of refrigerant was?? R22 cans are green and the common replacement for R22 would be probably 410A which would be a light pinkish color. The two don't mix and play well together.
 

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head pressure is way high for R22 did he try cleaning the condenser coil your metering devise is an accurator they very seldom go bad
if he mixed refrigerants then you will need to reclaim the charge evac the system and recharge it. do you know what the pressures were when the before the first guy added freon
 

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Discussion Starter #8
The tank was a bright dark blue, not a pale green like R22. The pressures were: H=275 and L=75. I did clean the condensor coil, it was already clean. The evaporator shown in pic#4 has an expansion valve? I thought it was simply a fixed size orifice. The compressor was drawing 12A for the 2.5 ton unit after he filled it. Not sure what is was before.

Greg
 

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Discussion Starter #9 (Edited)
I think this is what he put in. "MO99 is compatible with mineral oil and POE oil providing a quick, cost-effective R-22 replacement, and can be topped off during service without removing the entire refrigerant charge." I also read the EPA says don't mix refrigerants.


https://www.google.com/search?q=Dupont+By+Chemours+Isceon+Mo99,+Mo-99,+R438a,+Drop-in+R22+Replacement&client=firefox-b-1-d&channel=cus&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiO9PLw66rjAhUlFjQIHRdCCoQQ_AUIEigD&biw=1920&bih=916#imgrc=u2I3PjT1fG7FxM:
 

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Oh My...

Now what you have is 18 Opinions to sort through.

1. You Do Not Have a TXV. (Your system has a Piston)
2. Your Head Pressure and Low Side Are Too High. Clean The Condenser.
3. In older systems people mix Refigerants all the Time, It Is Against EPA 608. (In most cases it doesn't cause problems.)
4. With a Piston Evaporator you charge them by "SuperHeat". Looking at your numbers, it looks over charged some but the Head Pressure is Tooo HIGH (for an R22 system). If any of the Techs that worked on it did anything, hopefully they Did Not Put R410a in the system. R22 has come down in Price, but I'd dump 407C in it (it's cheaper) but you need to add some POE Oil.

NOTE. The Evaporator in Picture #4, has a Piston (not a TXV). Google a TXV.

Save yourself some headaches and Find an Honest, Knowledgeable Repair Tech in your area. $1500.00 is Bull Poop... At this point, I wouldn't pull the charge. I personally think it's Over Charged but need the Suction Line Temps and Pressures to confirm this.
 

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Had an AC guy check it and the readings were:

High pressure 325 psi @ 91*
Low pressure 97 psi @ 52*
Return air temp 79*
Chilled air temp 70*
Outdoor temp 89*
Attic temp 137*

He diagnosed either a failed expansion valve or block Freon tubes in evaporater coil. He also said the guy that added the replacement R22 screwed me because it shouldn’t be mixed with real r22 and now we can’t reuse the Freon if we replace the coil or valve. He also said there was no dryer/filter in the liquid line. At 20 years old, it’s time to replace the unit. Repair would be at least $1500.
Sorry to others options, but on a 20 yr old system, thats the right call, replace it. Sure you can bandaid it back together, but in 2 or 3 years the repair guy is back, then more service calls. Also new higher efficiency units will save on the unity bills. Pay me now, or continue to pay me later.
 

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Discussion Starter #13 (Edited)
Last Monday I placed another service call to the POS home warranty company and they scheduled the same handy man company to come back Friday afternoon for a second visit. I pay $65 for the visit so I called the company and ask to speak to the owner who is the most experienced AC guy they have, I was told. I spoke to his office person and was told they would give him the message which was, I wanted to discuss my options. The office person said the only option the warranty co allows is repair if parts are available and that I would have to pay additional cost of several hundred dollars for disposal etc. I'm waiting for the owner to call.

We had company from last wed to this morning so I had to run the unit and it ran from 0800 to 0300 then next day, everyday without turning off once.

Greg
 
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