A/C issues, startup, breaker trip

[rattle_snake]

Looking for some advice on my A/C woes.

I have a 2500sq ft home in PHX area with a pair of heat pumps, a 3T and a 2.5T Goodman. I think the 3T is a 2004 and the 2.5T is a 2011. Air handlers are from 1999

3 Ton unit
---------------------------------------------------------------------------------------
The 3T wasn't cooling when it was 120 outside. I observed the outside fan not running. It didn't turn freely. I had a friend who owns a A/C business come out and install a new fan. This unit seems OK for now.


2.5 Ton unit
------------------------------------------------------------------------------------
While he was out we heard the 2.5T unit's compressor kick on while the outside fan was running. Assumption here is compressor was in thermal shutdown. He measured cap, currents and line pressures said all looked OK. Later, unit wasn't cooling and I found breaker (20A) tripped.
Got a quote to replace unit but I wanted to know why it took a dump... So I opened it back up and looked for comp/fan coil shorts to GND. Didn't find any issues but noticed the cap (40/5uf) wasn't wired per schematic.
I rewired (Fan and comp start coils were reversed) and as expected, unit started, ran and was cooling. It ran for a few hours and got it's 1/2 of the house to set point.
On subsequent cycle it tripped the breaker (at 11pm, no sun on panel or unit). This morning, unit running I measure 1A of fan current and 7A for compressor which is inline with specs (1.10 and 10.8).
I measured startup current after a short off-cycle, the unit draws 58A (LRA=60) but does so for a few seconds before compressor actually starts. This is enough to trip breaker, but not a normal use case as thermostat has a minimum timer. Unit lists max breaker at 20A. Wire is 6ga. to panel, maybe 20ft.
So the compressor is on its way out, with thermal and starting issues. Since I am a cheap-*** SOB, I would like to keep this turd in service for as long as I can. Would a band aid like a 'hard start kit' (aka cap+relay) limp me though this summer? What else can I check?

Eventually the whole system(s) will have to be replaced.

 

[jav]

Sorry Justin-

it's a bit confusing to follow....

I'm not sure if your talking about the 2.5 or the 3t unit in the paragraph that starts "while he was out"?

Just before that you mention the 3t is "good for now" so I presumed you meant the 2.5t BUT then you say "I opened it BACK up" and found things mis-wired... and the only previous mention of wiring was on the 3t???... only "checked" the 2.5t.

Also- did you check pressures when (whichever) compressor was pulling 58A? Could the orifice or TXV have become obstructed causing high /low pressures to not equalize on a short cycle? Since the cap was reversed 40/5... did you confirm both sides were good?

 

[rattle_snake]

Sorry Justin-

it's a bit confusing to follow....

I'm not sure if your talking about the 2.5 or the 3t unit in the paragraph that starts "while he was out"?

Just before that you mention the 3t is "good for now" so I presume you meant the 2.5t BUT then you say "i opened it BACK up" and found things mis-wired and the only previous mention of wiring was on the 3t???

Also- did you check pressures when the compressor was pulling 58A? Could the orifice ot TXv have become obstructed causing high low pressures to not equalize?

Sorry for confusion. I will edit above.
Summary:
3T unit got a fan and is now OK.
everything below is about the 2.5T. I rewired the 2.5T and got it running. I don't have gauges to measure pressure.

 

[jav]

thanks-

so how long had the 2.5T been running with cap wired wrong? To start the compressor on just 5 micro farads when it should have been 40 seems problematic as that tolerance is usually 6% so the low side of the 40 should have been at least 37uF.

I'd double check your wire swapping just to make sure it wasn't correct originally.

 

[rattle_snake]

thanks-

so how long had the 2.5T been running with cap wired wrong? To start the compressor on just 5 micro farads when it should have been 40 seems problematic as that tolerance is usually 6% so the low side of the 40 should have been at least 37uF.

I'd double check your wire swapping just to make sure it wasn't correct originally.

24hrs, but it never started or ran like that. breaker was tripped.

Unit hadn't cooled since before he showed up, hence why I suspected he had disrupted something. I sent before/after pics to my A/C guy and he confirmed his mistake. It is currently wired as shown on schematic.

It is 122* and unit has been operating OK so far today. I bought a 5-2-1 hard start kit today locally, so I have the option to see if it reduces start up time.

 

[acmikee]

check your voltage.
also check the voltage drop across your breaker
what is the name plate min amps on the unit

 

[jav]

24hrs, but it never started or ran like that. breaker was tripped.

Unit hadn't cooled since before he showed up, hence why I suspected he had disrupted something. I sent before/after pics to my A/C guy and he confirmed his mistake. It is currently wired as shown on schematic.

It is 122* and unit has been operating OK so far today. I bought a 5-2-1 hard start kit today locally, so I have the option to see if it reduces start up time.

Sorry Justin-

from your first post- you listed the 2.5T unit as being a 2011... and also said that "while he was out" (working on the 3T) - you both heard the 2.5T compressor kick on while the fan was going- thinking the compressor had been in thermal shutdown. You also stated he "checked" things and everything seemed ok so I wasn't aware he had done anything to that unit.

So I think your saying that when he "checked things"... he rewired/miswired the cap? And when you say "later".. you mean the next day ( being the 24 hours the cap was mis-wired). Didn't you guys fire up that compressor after he checked it and created the miswire?

 

[eddieK]

Looking for some advice on my A/C woes.

I have a 2500sq ft home in PHX area with a pair of heat pumps, a 3T and a 2.5T Goodman. I think the 3T is a 2004 and the 2.5T is a 2011. Air handlers are from 1999

3 Ton unit
---------------------------------------------------------------------------------------
The 3T wasn't cooling when it was 120 outside. I observed the outside fan not running. It didn't turn freely. I had a friend who owns a A/C business come out and install a new fan. This unit seems OK for now.


2.5 Ton unit
------------------------------------------------------------------------------------
While he was out we heard the 2.5T unit's compressor kick on while the outside fan was running. Assumption here is compressor was in thermal shutdown. He measured cap, currents and line pressures said all looked OK. Later, unit wasn't cooling and I found breaker (20A) tripped.
Got a quote to replace unit but I wanted to know why it took a dump... So I opened it back up and looked for comp/fan coil shorts to GND. Didn't find any issues but noticed the cap (40/5uf) wasn't wired per schematic.
I rewired (Fan and comp start coils were reversed) and as expected, unit started, ran and was cooling. It ran for a few hours and got it's 1/2 of the house to set point.
On subsequent cycle it tripped the breaker (at 11pm, no sun on panel or unit). This morning, unit running I measure 1A of fan current and 7A for compressor which is inline with specs (1.10 and 10.8).
I measured startup current after a short off-cycle, the unit draws 58A (LRA=60) but does so for a few seconds before compressor actually starts. This is enough to trip breaker, but not a normal use case as thermostat has a minimum timer. Unit lists max breaker at 20A. Wire is 6ga. to panel, maybe 20ft.
So the compressor is on its way out, with thermal and starting issues. Since I am a cheap-*** SOB, I would like to keep this turd in service for as long as I can. Would a band aid like a 'hard start kit' (aka cap+relay) limp me though this summer? What else can I check?

Eventually the whole system(s) will have to be replaced.

I always start with the obvious, look at all connections between breaker and contactor...especially note contactor points. - You do need to observe pressures, be sure there are no air flow restrictions at evap (indoor filter) and note either the subcooling or the superheat to determine proper charge. A hard start is also a way to lower LRA draw

 

[rattle_snake]

check your voltage.
also check the voltage drop across your breaker
what is the name plate min amps on the unit

Voltage running was above 230.
min current req = 14.6A

Sorry Justin-

from your first post- you listed the 2.5T unit as being a 2011... and also said that "while he was out" (working on the 3T) - you both heard the 2.5T compressor kick on while the fan was going- thinking the compressor had been in thermal shutdown. You also stated he "checked" things and everything seemed ok so I wasn't aware he had done anything to that unit.

So I think your saying that when he "checked things"... he rewired/miswired the cap? And when you say "later".. you mean the next day ( being the 24 hours the cap was mis-wired). Didn't you guys fire up that compressor after he checked it and created the miswire?

Yes he mis-wired it. I found/fixed issue next day.
He should have verified the compressor would run after working on it I tried not to hover of the guy the whole time. Had to get a beer, it was freaking hot.

I always start with the obvious, look at all connections between breaker and contactor...especially note contactor points. - You do need to observe pressures, be sure there are no air flow restrictions at evap (indoor filter) and note either the subcooling or the superheat to determine proper charge. A hard start is also a way to lower LRA draw

He checked pressures while it was running/cooling and said all was OK. I think the last thing he did was test the capacitor...


So I did install the hard start kit and take some measurements for 'fun'. The increased phase delay to the start winding did help significantly. Under similar conditions, the start time decreased from about 3 seconds at 58A to almost nothing with a peak of only 12A. So about 10x faster at 1/4 the current, given the equipment I have. The unit has cycled and ran fine since installation, where it did not without.
So far. Time will tell and this thing will eventually die.

I had a hard time paying 3x for the hard start kit locally compared to what it is on amazon. I could buy another on amazon and return it to the local place, but that doesn't help the local business that had what I need when I needed it.

I may get a hard start kit for my camper a/c (12.5btu) that I run with a generator. It's a Honda inverter type, and I have it set to idle down when comp isn't running, so has to handle surge at low rpm. It works but voltage defiantly takes a big dip.

Also found out the air handler is only 2T. The PO moved the outdoor unit from one side of the home to the other, and likely installed this 2.5T goodman at that time. Given his other work, I am afraid to look at what happened to the lineset.

 

[zmaxmotorsports]

Sounds like it's time to match the air handler and outdoor system,then go from there.

 

[LS6 Tommy]

It sounds like you did well with your diagnosis. You really can't ever go wrong with a hard start kit and an 8-10 minute delay on break timer wired into the coil circuit of the compressor contactor.

I would say a thorough redo pf the PO's mess is in order, too...

Tommy

 

[My Old Tools]

Check the wire attachment at the panel, both the breaker and the ground. A loose screw will cause that. DAMHIKT.

 

[rattle_snake]

I checked the connections and they were all OK. I put a hard start kit on the 3T unit as well. The 3T started much quicker anyhow, so the extra 100uf didn't have as much as an effect. Peak current went from 37A to 27A, with RLA = 24A

The 2.5T unit has operated as should since I installed the hard start kit, 10 days ago. Without it wouldn't get more than a few hours before tripping breaker.
So I guess I can say my persistence, ability to correct the wiring, and the HS kit has deferred a ~$5k purchase of a replacement system for some amount of time. I told the wife I was going to spend it on another motorcycle instead, but I better save it for the inevitable.

 

[rattle_snake]

Digging further into these turds, I found a failed hack at ductwork on the 3T unit.

Both air handlers are the original units as far as I can tell. The 3T air handler leaked a LOT OF AIR, making the closet it was in nice and chilly. But I couldn't see anything wrong. A/C guy looked and didn't find anything when he was out. Even my wife knows it was a major issue so I finally reinvestigated.

I found a 1-1/2" wide by 20" gap between the air handler opening and the too small ductwork. The air handler (vertical) closet is very small and handler is hard up against back wall. so it was not possible to see it, I found using my phone camera. In the pics I see some hacked up sheetmetal, like someone with snips had a very bad day. It was a PITA, I sealed it up, but how someone could **** up something this bad and walk? I'm not sure....

I'm guessing 25% of the flow was not going into the ductwork.


The PO also put a 18 gallon storage tub under this air handler instead of unclogging the drain. Eventually it filled up with water, and I found it. Good times.

 

[mikebaker1129]

You were spot on with the hard start kit and rewiring the run cap.