AC compressor locked up...... now its ok ??

[kurt854]

R22 residential 2.5 ton, 13 seer basic central air..... i installed it 2 months ago, its been working great..

the evaporator coil has a txv on it.

the compressor locked up yesterday and was hot so i assumed it locked up.

so i was going to replace it, emptied the R22 and was about to cut lines and decided to check it one last time and it ran fine with no psi on the sysytem!!!

so i charged it back up and now its ok!!!

i no it wasnt over charged enough to add that much pressure to lock it up, everything checks out ok !!!

it has a recipocating compressor, (not the scroll compressor)...... i dont think that would be a problem with the txv???????

maybe the txv was stuck closed and psi build up was to much for compressor??????

i did install a filter very close to the evaporator coil, wich i removed before charging the system just in case that caused the problem... but it seemed clear and easy to blow through..... its gone now though.

any ideas on why it locked would be much appreciated..

[coolments]

Hi

If compressor was hot it most likley cut out on its own internall protection, common for engineers to mis-diagnose comp failure on a hot compressor. if you has tested the windings you would have most likely got an open circuit reading on tester. I always advise the customer that i would need to return and double check when comp had cooled down when coming across this.

P.S the filter drier was in the right place, always better as close the expansion device as possible.

Also R22, and you only installed it a few months ago....!!! crikey

[kurt854]

the thing that really got me going is the compressor didnt have an open winding, and when i put power to the compressor 240V it would hummm / buzzz like it wanted to run but couldnt.......

maybe it was overcharged with R22 but im 99.99% sure it wasnt. and it ran fine for 2 months.

its just driving me a little crazy because i installed it for a friend and i dont want him calling me every week telling me, o the compressor stopped running again.

[Pooh]

Kurt
it may not have been overcharged but it could have been undercharged which due to the high suction superheat the compressor may well have overheated and seized. The other option is has it got any capacitors on it if so are the connections OK?
Worth a check.

Ian

[coolments]

Pooh

Yeah from reading Kurts second post i to would now be looking at the capacitor, if the comp single phase

[kurt854]

Yes it has a round capacitor i believe it is a start capacitor, that was also my 1st thought..

it has been running fine now so im not sure that the capacitor would be bad, but i think i will change it out the next time it stops running ( if it stops again ) & ill let you know what happened.

thanks for the advice!

[Electrocoolman]

It will be a Run capacitor as most A/c compressors are PSC motors (permanent Split Capacitor). You can tell by its value and voltage rating (up to 30mfd / 450vAC rating)

[bigjabroni2002@]

It is always a good idea to put a hard start kit on a recip with a TXV.

[bigjabroni2002@]

Oh yea....Hello everyone. I am new to the forum but far from new to the biz, been around commercial refrig. 25 plus years and am currently a senior technical advisor for a large a/c and furnace mfg. Hope to get my hands dirty in here a little and maybe share a couple of war stories with you all.

[The MG Pony]

you are aware there is an introduction thread? This guy is asking a question, please try and keep it relevant to the thread you're in. Thanks.

If it is a residential A/C then it will be using a scroll engineered for A/C duty so adding a hard start kit to make up for an error is daft, much better finding and fixing the error rather then burning the motor up in a blaze of stupid.

For items that are using recip compressors a properly selected HST is viable. No thoughs cheap kits on ebay I would never call proper!

[bigjabroni2002@]

If I knew some of the guys in here were as rude as you, I would not have bothered. And if you read my first comment you would have seen I did give the best help he could have asked for. Believe it or not, you are way off base. I happen to know what I am talking about and you are arrogant. It is far from stupid and if you read the thread ,you would have seen it WAS a recip. And by the way, a scroll compressor may also require a hard start kit in rural areas where voltage may drop in peak periods when a TXV is used. Used them for years (potential relay and cap) with great success.(either that or call your electric co. and hold your breath)Have a great day.

[monkey spanners]

Some of the copeland low temp scrolls have a potential relay and start capacitor as standard.
None of my business but this is not a typical responce from The MGpony, maybe he's had a bad day

[bigjabroni2002@]

And I apollogize for blowing my top.

[Gary]

During the off cycle, refrigerant will migrate to the coldest part of the system, which is usually the evaporator.

If the evaporator is above the compressor with suction coming off the bottom, gravity will deliver liquid refrigerant to the compressor inlet, causing startup problems.

It is good practice to loop the suction line above the evaporator and then down to the compressor. This traps any migrated liquid in the evaporator.

[bigjabroni2002@]

Also a very good point , Gary. Anytime you have vertical seperation between evap. and cond., it is a good idea to have an inverted trap at the evap. to trap liquid so it will boil off when the comp. starts. In some cases with alot of vertical seperation a crank case heater is also an option. But with a no bleed TXV, your compressor will not equalize pressures and a hard start kit still may be the best bet, especially in peak times when a voltage drop can occur.

[The MG Pony]

I'm a bit sour to the Hard start kits! Way to many fried compressors due to their over use, a bakery is nearly going out of business becuase a previous tech shoved one random one on and the compressor is nearly melted, nothing against you personaly, not arrogant, just disgruntaled. and right now drunk, but the wine was the best I had in a long time!

[coolments]

Ok

One more thing to maybe look at, with the unit being R22 I assume you installed it second hand so it will have an antiquated control circuit, recips generally dont like starting soon after they have stopped (untill pressures have equalised) so if the stat energises the compressor to start instantly stat twiddlers will cause bedlam for it, if this is the case a nice delay timer fitted to it would help, say 5 minutes.

When i was an aprentice this used to happen a lot and also if the fuse size was tight it would blow, one of the engineers who taught me used to write on his service sheet ' unit not functioning properly due to KTB' which was knob twiddling Berks. Ah the good old days.

[monkey spanners]

I once wrote RTFM for "read the manual" on a service sheet, got called into the office for that one

Also once put shortage of secondary refrigerant for an ice builder and had to explane to the boss that this meant water level low as he wanted to know how much gas to charge them for

Jon