a-coil wont get cold enough

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Originally Posted by ultitech

im saying my pressures are in range of where they should be for a 90 deg day. Pressure alone is not a good diagnostic metric. they are not indicating a problem but the line set temp is stuck at 80degs I assume that you mean the suction line temperature.which is not in range and i said the needle goes into retard when charging a r-22 unit with r-22 gauges not pass retard but when you close your valve the needle should quickly go back up not take 3mins to go back up ( i replaced the valve core as well). I think this is a red herring. Forget it for now. the unit is 12 yrs old So what? and is just now having a problem, its not a airflow problem and it doesn't matter how much more freon i put in, the pressures will keep going up like normal but the line set temp will not budge. After i replaced the liquid line dryer and got my head pressure down the compressor doesn't overheat anymore and has been running for 3 days but still the evap only gets cold and sweats on the bottom of the coil, its completely dry on the top half. It doesn't matter what my cfm, wetbulb or temps are, the coil should be saturated top to bottom. for some reason the freon is just not flooding the coil. Im leaning toward a compressor problem.

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I've made some more notes in red. I was in a hurry earlier to go to dinner with my family.

I also highlighted what I believe to be the error in your logic in blue. Could you please explain to me why you believe that a compressor problem, with what you claim to be "perfect pressures" could be causing your problem?

The compressor is pumping, you needn't ask more from it at this point in time.

As requested, please take the requested readings and post back. We'll explain what the problem is and WHY we know it to be the problem from the information that you haven't yet provided.

So Blowing a Ton of Hot air across your coil wouldn't cause it not to be wet? I think you better run the unit close the liquid line valve and see if your gauge Retards.
Or just listen to JP advice cause he knows his Refer
We need more info to help you

I will say air flow is MOST DEFINITELY something to check.

Had an almost same situation today, low TD, low pressures, warm coil, SH & SC off and they wanted on one of our maintenance policies.

Mind you, this unit was installed as a package with a furnace in 1995 by others. We have serviced the furnace since 2002, but only replace the capacitor in the outdoor unit and nothing else done according to the service sticker.

Well it was a 75K furnace with a 1.5T a/c with blower tap for cooling on high.

I found an old invoice with a reading of 11555 CFM, 50/120 PSIG, 74° AMB and a
16° TD. This was also after he added a LB of refrig because he replaced the core due to a leak( maybe low pressures due to improper, too much, airflow?).

Duct work is spotty at best.

Lowered to heat tap, which was 752 CFM, lowest possible, got a 16° TD, but it is, was and will always be WRONG!!!

So YES airflow matters!!!!!!!

This is just a wild guess from a new student. I am thinking oversized orifice because of low superheat with high suction side pressures.
:confused:

JASON sent this from his DUMB-PHONE

Definitely need all your data:: return dry bulb, return wetbulb, supply temp, outside ambient, low pressure, high pressure, liquid line temp, suction line temp, condenser saturation temp, and evap saturation temp, with all those numbers you can tell exactly what is wrong, no ifs ands or butts. Science doesn't lie

Quote:

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Originally Posted by TriplePoint

This is just a wild guess from a new student. I am thinking oversized orifice because of low superheat with high suction side pressures.
:confused:

JASON sent this from his DUMB-PHONE

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Where did he post about low superheat?

give the guys want they want.... superheat wet bulb dry bulb and you will get help..... no info we cant help.... and 80 suction is not really all that normal

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Originally Posted by jpsmith1cm

Where did he post about low superheat?

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I assume the 80 was suction temp then looking at his pressure 225=77 sat. temp.

JASON sent this from his DUMB-PHONE

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Originally Posted by TriplePoint

I assume the 80 was suction temp then looking at his pressure 225=77 sat. temp.

JASON sent this from his DUMB-PHONE

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I made the same assumption, so he is running an 80 pound suction which is about 48 degrees SST, giving him 32 degrees of superheat.

225# head is about 109-110 SCT.

Where the heck did you get 77 degrees from?

Quote:

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Originally Posted by jpsmith1cm

I made the same assumption, so he is running an 80 pound suction which is about 48 degrees SST, giving him 32 degrees of superheat.

225# head is about 109-110 SCT.


Where the heck did you get 77 degrees from?

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Damn I was looking at 410 pt. :eek:
Rookie mistake. Lol

JASON sent this from his DUMB-PHONE

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Originally Posted by TriplePoint

Damn I was looking at 410 pt. :eek:
Rookie mistake. Lol

JASON sent this from his DUMB-PHONE

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:LOL:

I don't work with 410a enough to know the numbers like I do with 22, otherwise I would have spotted that right away.

One of these days I am going to correctly diagnose one of these internet service calls. :D

Jp, is SST suction superheat temp and SCT subcool temp ?

JASON sent this from his DUMB-PHONE

Quote:

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Originally Posted by TriplePoint

One of these days I am going to correctly diagnose one of these internet service calls. :D

Jp, is SST suction superheat temp and SCT subcool temp ?

JASON sent this from his DUMB-PHONE

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Saturated Suction Temp
Saturated Condensing Temp