Help! American Standard 18SEER

[smoke]

Rain or undercharge.
If there are noncondensibles you will see an un-even frosting pattern across the whole coil.

~smoke~

[JMack13]

The OAT has not been below 34 & theres been no ice or anything on the house. The unit is on the eve end of the house so forget about water running off the house into it..& r glasgow, the top few rows of the coil are froze really big, not water freezing all across the top of the unit?

[JMack13]

& if it were non CONDENSEables would that not be in the top of the condenser?? Not causing problems in the evaporator right?

[JMack13]

Thanks for the input Brent..i'm trying to get my post count up! This is good info but still doesnt explain why it's freezing only at the top..

[Brent Ridley]

Jmack,

We can't diagnose the problem for you.

We can only offer "suggestions." It is very difficult to pinpoint a service issue such as this one from a keyboard.

You're a technician. Use yours skills, along with info provided and determine the issue. Let us know what you find!

[rglasgow]

Jmack, not sure of that particular coil but refrigerant does not generally enter from one end and exit the opposite end be it top or bottom. The coil has several different circuits. After completely defrosting, run in heat mode with no outdoor fan and observe for frosting pattern. May point you in the right direction.

[beenthere]

Merged your 2 threads. please don't make duplicate threads, thank you.

[JMack13]

My intentions werent to get a diagnosis. It was simply to discuss the 18 SEER 2 stage system & see if this was "normal". (& get my post count up) Could someone else chime in on the liquid entering the bottom & vapor leaving the top? Thats what all of my text books show & both of my college teachers.

[Chuck]

My intentions werent to get a diagnosis. It was simply to discuss the 18 SEER 2 stage system & see if this was "normal". (& get my post count up) Could someone else chime in on the liquid entering the bottom & vapor leaving the top? Thats what all of my text books show & both of my college teachers.

There are 7 circuits on a 3 ton (may be more on 4 and 5 ton models, haven't counted) and they are evenly spaced top to bottom. So the part that's freezing could be one or two circuits.

If you open the side panel pull that black plastic sheet out of the way, you can see the vapor manifold and see exactly how the coil is piped.

I have this unit in my house, the water source version.

[air1]

It could have several distribution tubes distributing the refrigerant to the different circuits in the outdoor coil. The top one is probably restricted.

[JWB]

run it in ac for a couple hours, the heat will melt the ice. just kidding. it is 75 down here right now.

[jtrammel]

Sounds like a restricted distributer tube like air1 said.

[beenthere]

My intentions werent to get a diagnosis. It was simply to discuss the 18 SEER 2 stage system & see if this was "normal". (& get my post count up) Could someone else chime in on the liquid entering the bottom & vapor leaving the top? Thats what all of my text books show & both of my college teachers.

Often text books will show an over simplified example/drawing. Your college teachers are wrong if they think all evap coils are set up with a single feed in the bottom of the coil. It will be multiple circuits with the bottom of each circuit being feed at its bottom.

You need to look closer at the systems you work on.

[JMack13]

Thanks guys. I do look at them & i'm still learning every day but ya'll don't understand this small town AL stuff. We might go a year without seeing anything above a 10 SEER!

[ga-hvac-tech]

Thanks guys. I do look at them & i'm still learning every day but ya'll don't understand this small town AL stuff. We might go a year without seeing anything above a 10 SEER!

Used to be 75% of what I saw was builder grade... Now I have a customer base that wants better. Takes time to build that base.

How about filling out your profile with a city/state... then we will know the climate you are in.

[Thermodynamics]

The temperature sensors have an ohm reading related to the temp being read. Your trane service manual will have a table to follow for these measurements. Just something worth checking out.

[DOGBOY]

10 seer or 18 seer Trane or Goodman all are designed similar meaning all circuits are very much the same maybe 4 to 9 inches in height on a cond. coil and as stated has many and the size dictates how many circuits, evap coil not the same but has several circuits maybe 2 circuits per ton. any one circuit could be restricted we and you can not tell over the phone or computer. so just because it is an 18 seer it is still a normal heat pump circuit refrigerant circuit and defrost the same.

dogboy

[smoke]

Maybe it's only running single stage and never ramps up.
When I find a heat pump with half, or less, of the outdoor coil frozen solid it usually means under charged. If it's a 2 stage heat pump maybe it never comes out of 1st stage

[rfelectron]

Check subcooling. I would guess either low subcooling and the top circuit not getting a solid flow of liquid or a restriction in the top circuit.

[JMack13]

Solid flow of liquid in the top of the evaporator?...