Needing some trouble shooting advice with a 3.5 ton split

[Bobe5531]

We replaced the original compressor because we thought it was seized because it was drawing Lra on start up.

So I got a new scroll and ohmed it out. Theres no way this comp is busted. I dont even think the original hermetic compressor is seized either. I think there is a electrical issue but can't pin point it.

Took the comp back to the house and installed in condensing unit. Started it up and it is doing the same thing. Drawing Lra and opening the overload as soon as power is supplied.

Did not check min circuit amps will check today.

Maybe you can take a compressor that you know is working fine and hook that up to the same power supply at this house and see if it starts fine. Atleast that will help narrow it down as whether its a bad compressor or a wiring/power supply issue

[timjimbob]

Had a rent house, last month, with occassionally energized water pipes. Really bite you. Getting ready to rent. Installed new CU and ran fine.

After tenant complained of shocks while taking shower, Come to find out neutral, at pole, was not connected.

But Never an issue with CU though.

Here's where I think your measurements were incorrect. "checked each leg to ground, 200+ volts to one side, minimal to other". I think you checked to metal cabinet and this was not actually grounded.

[Nonintelligetis]

Not my first rodeo bubba- always check legs to the ground wire. I spent a solid half hour double checking the diagnosis at the breaker panel. There were no mistakes in my service call, but I will allow my interpretation of the reason for the compressor not running to be challenged.

[timjimbob]

In my case, I had the electrician add ground rod and bond all pipes to ground, at panel. Still had a shock hazard. Our dry soils just didn't make a true ground even with buried copper water line and two rods 5 feet deep.

Electrician gave up until he glanced up at the pole and saw the disconnected neutral.

[Swinder]

Take a close look at the wiring diagram for the unit that you're thinking about, and it will immediately become apparent to you why it's important those two wires are in the position that they're in.

I'm not arguing with you by any means, I'm just wondering if you could clarify why switching T1 and T2 would cause an issue?

[Mr Bill]

Probably a complete restriction in a drier or metering device, or pump down valve closed.

[socotech]

Open your service valves

[KB Cool]

Maybe the discharge lines completely plugged! Factory defect! Pop the discharge line and liquid line and see if you can blow through it with nitrogen!

[Milk man]

[QUOTE=Nonintelligetis;15856401]Bad neutral to the house sends 115V appliances searching for a neutral through 230V appliances leading to greatly increased (or decreased) voltage on a single leg through the capacitor. W/ no perpendicular induction forces to start the motor it simply drew heavy amps and locked out. Weirdest thing I ever had to diagnose- not a likely scenario at all. My point was to get the OP to check input voltage first as you stated


To the point of the bad wiring, I've received a lot of defects from manufacturers on new equipment, but never incorrect wiring. Is this a problem anyone has run across?[/QUOTE]

yes, I have

[Nonintelligetis]

yes, I have

I should amend that question- how often do you run across factory miswiring?

[Mr Bill]

I should amend that question- how often do you run across factory miswiring?

I have run across a couple new Ruud condenser installs in my travels, were the fan and herm were switched on the cap.


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[hurtinhvac]

Take a close look at the wiring diagram for the unit that you're thinking about, and it will immediately become apparent to you why it's important those two wires are in the position that they're in.

Huh? You mean L1 and L2 mixed up?

As opposed to line and load - 'cause that shouldn't make a difference, right? As long as the leg that's going to common is not the same one going to start and run...?

[Milk man]

One time

[Nonintelligetis]

I have run across a couple new Ruud condenser installs in my travels, were the fan and herm were switched on the cap.

I installed Rheem for ~ 3 years, Nordyne for 2 and AS for 4 not to mention countless minisplit varieties. Must have gotten quite lucky- thanks for the data. I'll def keep that bit of info in mind next time I get called behind our installers

[Borbs24]

System I beilive is not plugged because when I charged it back up it equalizes on both sides.... And if it was plugged it would still try to run a bit I would assume?
The overload opens instantly upon power being supplied. Draws 120amps and then she opens and it all happens within a matter of a second.

Had a electrican come to check out the panel and wiring and everything checks out he said.

I have no clue now and it's starting to drive me crazy.

[SteveRAdams]

1) Make sure your valves are open on refrig lines.
2) Check voltage from leg to ground on each phase of the line side.120 v each leg. Do the same with each leg and neutral
3) Make sure contactor isnt cracked causing a bad connection. Thus the tripp.
4) Is there a stepdown transformer?
5) What brand and model number is this unit?

[Mr Bill]

And if it was plugged it would still try to run a bit I would assume?

I have to disagree, if its totally plugged, it will not start at all. I have seen this many times in the old Ruud units were the drier was behind the compressor, and gets plugged.


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[GT Jets]

Found one at my buddy's rental house today..

One of those slim carrier POS units, 3.5 ton, had a capacitor all fat and unhappy, unit would not run... Change it out, still wont run... Old capacitor tested at zero nf..

A quick check of the wiring and the L2 jumper from the line side of the contactor to the "C" on the capacitor was on the wrong terminal on the 1 1/2 pole contactor, a quick switch from T1 to T2 and unit ran well enough to know it was low on charge....

Whoever did the work on this thing last year lost a potential job forever....

[timebuilder]

Huh? You mean L1 and L2 mixed up?

As opposed to line and load - 'cause that shouldn't make a difference, right? As long as the leg that's going to common is not the same one going to start and run...?

No, I mean the wires configured on the load side of the contactor. When you are creating that artificial second phase using capacitors in a single phase system, it's important that any two wires have the correct relationship, as long as they are not L1 and L2 on the line side. The position of THOSE two wires makes no difference.

[timebuilder]

A quick check of the wiring and the L2 jumper from the line side of the contactor to the "C" on the capacitor was on the wrong terminal on the 1 1/2 pole contactor, a quick switch from T1 to T2 and unit ran well enough to know it was low on charge....

Whoever did the work on this thing last year lost a potential job forever....

Yes. That's what I was talking about.