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View Full Version : 1.5 ton Goodman can't figure it out. Help!



Martinez4256
07-19-2016, 04:24 PM
Ambient Outdoor Temp: 95
Indoor: DB: 85 WB: 75
Suction pressure: 95
Head pressure: 270
Suction Line Temp: 83
Delta Temp at air handler is only 8 degrees
I was told to check compressor for weak valves but so far the compressor checked out good electronically and mechanically. No matter how much refrigerant I take out or put in, Delta Temp remains 8 degrees

Cimerian
07-19-2016, 06:43 PM
Do you have a heat strip running?

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CircusEnvy
07-19-2016, 08:43 PM
Are we talking about R22 or R410A? TXV or piston? What does the charging chart on the unit say?

Just some questions to ask yourself. Can't go into too many details with this being a public forum, but with a 1:3 compression ratio, I highly doubt it's the compressor.

amd
07-19-2016, 09:50 PM
Check your fan speed, could have very excessive airflow across the coil along with other problems.

rsmith46
07-19-2016, 10:31 PM
Goodman we can assume piston and r22, 75* IWB and 95* ODB the SH should be 25*. You have 26* SH, charge is ok. With a 75* WB an 8* delta-t might be the best you'll get. Let it run overnight and see if indoor temp drops and delta-t gets better.

Martinez4256
07-20-2016, 10:30 AM
Do you have a heat strip running?

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Checked that. They are not running, nor is it broke and grounded out

Martinez4256
07-20-2016, 10:38 AM
It is still doing 8degree delta T. One thing I noticed was that the indoor coil felt about 75% full. The coil was replaced about a year and half ago.

Poodle Head Mikey
07-20-2016, 10:39 AM
How much air flow across the indoor coil? 600 CFM is not very much. Did you try reducing the air flow to bring the DT up a bit? To say; double. <g>

PHM
------





Ambient Outdoor Temp: 95
Indoor: DB: 85 WB: 75
Suction pressure: 95
Head pressure: 270
Suction Line Temp: 83
Delta Temp at air handler is only 8 degrees
I was told to check compressor for weak valves but so far the compressor checked out good electronically and mechanically. No matter how much refrigerant I take out or put in, Delta Temp remains 8 degrees

Martinez4256
07-20-2016, 10:45 AM
R22 piston. The charging chart was stated a 22-25 degree superheat. So I believe my charge is ok. I was told with a bad compressor valve, pressures and superheat would appear normal to slightly high

Poodle Head Mikey
07-20-2016, 10:53 AM
Condenser in: 95
Condenser out: ??
Head press: 270 = 123 (?)
Where were the compressor amps while all this was going on?






A
Ambient Outdoor Temp: 95
Indoor: DB: 85 WB: 75
Suction pressure: 95
Head pressure: 270
Suction Line Temp: 83
Delta Temp at air handler is only 8 degrees
I was told to check compressor for weak valves but so far the compressor checked out good electronically and mechanically. No matter how much refrigerant I take out or put in, Delta Temp remains 8 degrees

Cimerian
07-20-2016, 11:00 AM
Really doesnt appear you have a compressor issue. If you're sure there is no heat being added by a heater or a return duct then I'd do a freeze test to ensure no restrictions in evap coil.

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hedrash
07-20-2016, 01:13 PM
It is still doing 8degree delta T. One thing I noticed was that the indoor coil felt about 75% full. The coil was replaced about a year and half ago.
Well should be relatively "full", the evaporator requires liquid flashing through most of it to effectively absorb heat.

We can control fire & ice.....

Martinez4256
07-20-2016, 01:16 PM
How much air flow across the indoor coil? 600 CFM is not very much. Did you try reducing the air flow to bring the DT up a bit? To say; double. <g>

PHM
------
No I did not mess with the airflow. The system is 14 years old so it's been running on the same fan speed for years, I doubt it would be causing a problem now. My compressor amps was at 5.3, it's rated at 6.7

amd
08-30-2016, 07:59 PM
is it possible that the piston may have become unseated and some refrigerant is bypassing?

how was the compressor mechanically checked? was it pumped down?

heat strips or furnace by any chance upstream of evap coil?

here's a chart with supply air temps-> http://efficientcomfort.net/Charts/Charging&TDchart.pdf split should be be 13f with 600 cfm so if u have high airflow like 700+ it may not be far off at all.

heatingelement
08-31-2016, 01:51 AM
Low on charge. Condenser coil clean?

udarrell
09-06-2016, 01:29 PM
You don't have high amp draw; Rated 6.7 drawing 5.3-amps.
You have high head pressure (& suction pres.) but somewhat low amp draw, this is why Mickey said to check the air-temp coming off the condenser (it's always important) as it will probably be a lot lower temp than the head pressure reading indicates.

Thus; low indoor delta-T & 'speculating' low outdoor condenser delta-T; refrigerant system not functioning normal... Super heat is about 27F, usually rather high with a restriction; don't know what subcooling is, but it is also important to know...

This seems to point to a restriction somewhere in the refrigerant system.
I am speculating that it is way over-charged so suction & head are both high; but if not it blows my assumptions out the window.

town
09-07-2016, 10:02 PM
Since is 14 years old and there is not a service record, remove freon, install new freon and let as know what is going to be the new reading

DOGBOY
09-11-2016, 05:11 PM
Ambient Outdoor Temp: 95
Indoor: DB: 85 WB: 75
Suction pressure: 95
Head pressure: 270
Suction Line Temp: 83
Delta Temp at air handler is only 8 degrees
I was told to check compressor for weak valves but so far the compressor checked out good electronically and mechanically. No matter how much refrigerant I take out or put in, Delta Temp remains 8 degrees

I say weak valves. I had one last summer

3 ton
97 suction
270 high
6* sh
11* td

replaced compressor

68 suction
265 high side
20* sh
17* td

throrope
09-11-2016, 08:14 PM
Since is 14 years old and there is not a service record, remove freon, install new freon and let as know what is going to be the new reading

I agree, but I suggest putting back the same refrigerant in the right amount. If the old stuff is bad, the owner has other problems and doesn't need the expense of a full R22 charge. I suspect you're not the first to look at it in 14 years. Pulling a vacuum like a new install will also remove air pumped in by prior "chargers". Then you'll be able to diagnose any remaining issues.

Our replacement goodman condensing unit installed on a Trane heat pump AHU didn't have electric low and high pressure switches. The tech suspected it continuously lifted the compressor relief valve until it gave up.
I'm thinking either a mismatch with the evap coil or the guy who replaced the unit didn't braze with nitrogen and subsequently the TX valve got clogged. The all new Trane system has electric cut-out switches.

town
09-11-2016, 08:45 PM
Remove refrigeration and add a new with really good vacuum