A/C Giving me problems! Advice needed

[scott250ratc]

Hi, I'm new to to the forums. I'm looking for some advice on what I am not seeing with this residential unit. It's about 70 degrees outside right now.

I have the condensing unit running at 67lbs suction and 125 discharge. R22 The discharge air temp out of vents is only 62 degrees? The slab evap coil is clear, I think the airflow is adequate. It has a fixed orfice. The suction line isn't sweating at all.....

There is no liquidline filter drier, everything is ancient and missing stickers... if there was non condensables in the system wouldn't the head pressure be high? I just don't get why the evap isn't taking the heat. It has an orfice number 67 sticker on the casing, Whether this unit has ever worked right is unknown. Your thoughts? Pull the charge and start over?

Thanks,
Scott

[jeremyhall.tech.sc]

if you are a tech................ read : NO DIY!!!!!

pull blower . clean blower wheel.

clean evap coil ( back wash) .

clean condenser coil ( back washing also) .

then calibrate guages to 0psig. and check pressures again.

then physically check ALL ducts for blockages....

[jeremyhall.tech.sc]

also please fill out your personal info completely. :bump:

[scott250ratc]

Thanks for the reply, I'll look into it more. So you would agree this is related to airflow? I read the site rules, I apologize if I'm out of line pertaining to DIY.

[jpsmith1cm]

Thanks for the reply, I'll look into it more. So you would agree this is related to airflow? I read the site rules, I apologize if I'm out of line pertaining to DIY.

We don't know WHAT is the cause.


You haven't given us enough information.

[mark beiser]

Thanks for the reply, I'll look into it more. So you would agree this is related to airflow?

Not enough information has been given for anyone to even begin to diagnose the problem, or even make an educated guess.

[DLZ Dan]

Use a veloptometer and see what your airflow is. Do all the normal tech things and then let us know how you did.

[scott250ratc]

I have more information I obtained today:

Condensing Unit - American Standard 10 seer
Model atro25c100a1 - is that 25000 btu?

Slab Coil - American Standard
Model - txfc36a4hpao 36000 btu I would presume
orifice 67

Furnace Goodman
Model - gmpn100-4 rev b
1/2hp fan motor

Pulled blower and cleaned it, already cleaned evap coil and condensing unit. Fan is wired for high speed on cooling. Dan, I will get some cfm readings as soon as I can.

So is having a larger indoor coil with an orifice helping the situation at all? I always thought they should both be rated to handle the same btus

[catmanacman]

Possibly short on gas and or to much airflow

[mark beiser]

Sooo, a 2 ton outdoor unit with a 3 ton indoor coil and metering piston, and a furnace with a blower that is over sized for 2 tons of cooling, even when set on low speed.

[DLZ Dan]

:payattention:
Sooo, a 2 ton outdoor unit with a 3 ton indoor coil and metering piston, and a furnace with a blower that is over sized for 2 tons of cooling, even when set on low speed.

[scott250ratc]

Sooo, a 2 ton outdoor unit with a 3 ton indoor coil and metering piston, and a furnace with a blower that is over sized for 2 tons of cooling, even when set on low speed.

Do I need to have the space sized for new equipment then? Since it's just hacked together and not sized correctly, is it even worth the trouble??

[scott250ratc]

I ended up putting a txv on the system, charged by subcooling. It works awesome now in case anyone cared to know.

[stonefly]

it ain't pretty but sounds like you did good. your own system?
welcome to the forum, folks here are a lot warmer when you don't seem like a homeowner about to put himself in danger.

[scott250ratc]

Yeah it's my own system. I got into the trade 4 years ago doing grocery store install and service that's all I've done.

[wahoo]

Good move, the TXV will adjust itself to compensate for "mismatch". Good job. I'd also check the air in /out temp drop as the fan may actually be set too high and moving too much air to properly dehumidify the home.:.02:

[udarrell]

Maybe the piston orifice wasn't switched from the evaporator 3-Ton size to the condenser's 2-Ton+ capacity orifice.

A correctly sized & refrigerant type TXV is the way to go, I wouldn't want a system without a TXV metering device.

[scott250ratc]

Man what you guys just said is exactly what I thought. I actually did check the td across the evap, it was 20 degrees. Good lord why wasn't this done in the first place?

[mark beiser]

I wouldn't want a system without a TXV metering device.

:ditto:
Slug of brass with a hole in it for metering + widely variable operating conditions = dumbest idea ever.

Now if they would just go back to building TXV's like they did before the increased efficiency mandates increased demand for them, and sparked a sprint to the bottom in valve price/quality, we would be much better off...

[beenthere]

:ditto:
Slug of brass with a hole in it for metering + widely variable operating conditions = dumbest idea ever.

Hmmm, sounds like an orifice for a gas furnace.

[beenthere]

manofmanyfish1990, this is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise here. Please apply to the AOPC today, thank you.

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