View Full Version : overloaded compressor
Royal241
30-06-2009, 04:35 AM
I have a 1.5 HP running on R12, or 414B, not marked. Draws 12 amps, should be 9.7amps. First I saw 14 A, I adjusted the charge and now is 12, runs for a while, bring the temp to 40F then the protector opens for a 1/2 hr. Suction is 20, discharge 200, condenser clean, fan turning the right way. History of the box: installed 6 months ago as used and the mechanic ran away, customer says it was ok for a while...but don't think so. The compresor is rated at 6000 btu, evaporator 3000 btu, discharge line is 1/4", evaporator fan blows towards the back.
Changing the discharge line to 3/8", reversing the blade at the evaporator, changing the ***** to "Hot Shot" would solve all my headaches? Am I missing something? Thanks guys.
I'm going to take a wild guess and say this is a walk-in cooler? TXV?
Royal241
30-06-2009, 05:02 AM
Yes sir TXV
Is this a factory built condensing unit?
What is the temperature of the air entering the condenser?
What is the temperature of the air leaving the condenser?
Royal241
30-06-2009, 05:14 AM
Factory built, 80F ambient in that basement
If it's factory built, they installed the proper sized discharge line.
Royal241
30-06-2009, 05:25 AM
condenser is factory built, but was intalled this way by someone. there is a 3/8' coming out of the receiver, and a reducer before the drier going to 1/4, makes me think that the guy ran out of 3/8 and did it 1/4
Royal241
30-06-2009, 05:27 AM
120 F coming out of the condenser
You are not getting enough airflow through the condenser. Either it is dirty or the fan blade is dirty or turning the wrong way. Or maybe the fan blade is flipped over so that it backhands the air instead of scooping it.
Is the airflow push-through or pull-through?
Royal241
30-06-2009, 05:51 AM
Gary, the condenser is fine, the blade is turning the right way, it's scooping, the drier is not hot, but why the overload on the compressor? I am leaning towards undersized discharge line... thank you.
What's the liquid line temp near the drier?
I am leaning towards overcharge, but the pressures don't tell us much if we don't know what refrigerant is in the system.
Royal241
30-06-2009, 06:23 AM
I dont know
but there is no restriction in the drier, thinking of it, is the same as after
Royal241
30-06-2009, 06:27 AM
I took ***** out until it started to bubble, just a little, that's how I dropped the amperage, so it's no over charge, maybe mixed *****?...
wish my dad was here, he would tell me: U stupid, U didn't figure it out, lol
Royal241
30-06-2009, 06:28 AM
I will pump down, change the discharge line to 3/8, drier ofcourse, and see what happenes
condenser is factory built, but was intalled this way by someone. there is a 3/8' coming out of the receiver, and a reducer before the drier going to 1/4, makes me think that the guy ran out of 3/8 and did it 1/4
That's the liquid line, not the discharge line. The discharge line goes from the compressor to the condenser.
The 1/4 liquid line is plenty for a 3000BTU evap.
Royal241
30-06-2009, 06:30 AM
ahh, F it, I will do the ***** change over, save a drier and charge the guy $500
We need the liquid line temp.
Royal241
30-06-2009, 06:34 AM
sorry, i ment the high side, in my mind was discharge line, but I see it now
Royal241
30-06-2009, 06:34 AM
think was 98F
[I]I took ***** out until it started to bubble, just a little, that's how I dropped the amperage, so it's no over charge, maybe mixed *****
Or maybe air in the system. Either way evacuate and charge is called for.
After you do that, let us know the air in/out temps on the condenser. The dT (difference between air in and air out) should be no more than about 30F. Right now it is 40F dT.
If R12 @ 200psi, the SCT is 138F minus 98 = 40F subcooling. This should be no more than 15F.
If 414b @ 200psi, the SCT is 128F minus 98 = 30F subcooling. Again, it should be no more than 15F.
Either way the subcooling is way too high, indicating either too much refrigerant... or air in the system.
Royal241
30-06-2009, 07:07 AM
wow, U sound like my father, don't sniff 2 much *****, my friend, TY
Royal241
15-07-2009, 01:03 AM
Ok My Father passed away on July 1st, he should be considered one of the best that there was, sience he disigned a milk factory at the age on 24, and still running; back in Romania. After catching up with all the other call I made it back to this guy with the overloaded comnpressor. Ready for this?
Changed the gas to Hot Shot, suction 20, discharge 160 ambient at condenser 75F. Compressor rated 9.7A pulling 12A. after 20 minutes stoped on the protector. Took some gas out, Amps down to 10.7 suction 15 discharge 140, inside box I get 50F, compressor stops on the overload after 20 minutes. Compressor hot to touch, leaking oil on the suction valve, sight glass bubbling after droping the charge, suction cold but not sweaty, after closing a half turn the expansion valve. What is going on? Compressor ran out of oil and is causing this overloadong, is a hermetic. Weak protector? I am ready to change the compressor, but am reluctant. Any help would be really nice, Thank You! Any help would be really nice, Thank You!
Sorry to hear about your father.
After catching up with all the other call I made it back to this guy with the overloaded comnpressor. Ready for this?
Changed the gas to Hot Shot, suction 20, discharge 160 ambient at condenser 75F. Compressor rated 9.7A pulling 12A. after 20 minutes stoped on the protector. Took some gas out, Amps down to 10.7 suction 15 discharge 140, inside box I get 50F, compressor stops on the overload after 20 minutes. Compressor hot to touch, leaking oil on the suction valve, sight glass bubbling after droping the charge, suction cold but not sweaty, after closing a half turn the expansion valve. What is going on? Compressor ran out of oil and is causing this overloadong, is a hermetic. Weak protector? I am ready to change the compressor, but am reluctant. Any help would be really nice, Thank You! Any help would be really nice, Thank You!
Here is a reading assignment for you:
http://www.refrigeration-engineer.com/forums/showthread.php?t=19701
This should bring you up to speed. Then we can discuss what we know and don't know about this system, given the current information or lack thereof.
Royal241
15-07-2009, 02:43 AM
very nice written Gary, but my simple question is: how can I lower the amperage drawn by a compressor, keep in mind that I have low discharge and low suction. Am I right that loss of the oil will increase the amperage? Hmm, I laugh at my own insecurity... Thanx!
Check the voltage at the compressor terminals with the compressor running. If the voltage is low, then there is a resistance in between the compressor and the power supply. Burnt contacts, loose connections, undersized wiring, etc.
Also check the run capacitor if this is single phase.
Royal241
15-07-2009, 03:04 AM
single phase, 220, replaced relay, checked run and start cap, start cap droppes on time, everything thight, voltage 219. Now That I think, the compressor terminals have female spades attached to it, and it didn't look right to me, but the connection was tight.
Sounds like you have pretty much narrowed it down to the compressor, then. Probably tight/worn bearings. At this point I would replace the compressor.
Royal241
15-07-2009, 04:08 AM
Thank You, I was looking for some assurance, man, I miss my dad, he was 64, and always said that there is no stupid question...but stupid not to ask. Well, I miss him, and my mind is not at work as much as it should be. Thank you again, and BTW I ordered the compressor earlier in the day. I will let U know the end result in a few days (got a couple of emergency calls for tomorow).
You are OK.
Powered by vBulletin® Version 4.2.1 Copyright © 2024 vBulletin Solutions, Inc. All rights reserved.