Unit with no refrigerant with compressor not running.
Hello this is my first post. I am an apprentice with a little over one year work experience and alot has been spent picking up and delivering parts. (limited experience as you can guess)
I have been working at a daycare and I found a split unit running but no cooling so I tossed my gauges on and the pressures read 0 psig so there was no refrigerant. So I know there is a leak and the compressor isn’t running.
I am not sure if the compressor is shot or not. My guess would be yes because I assumed it ran in a vacuum. My question is how do I make sure the compressor is actually bad. I’m weary to try and bump it on in case it isn’t and run it in a vac and piss off the mechanic I work with.
Any help would be great. Try and help me impress the guys who I work with a bit. Thanks.
04. 26. 2011, 11:21 # 2
Join Date Jan 2009 Location Fairfield county Connecticuit Posts 803 Post Likes Likes (Given) 0 Likes (Received) 2 Dislikes (Given) 0 Dislikes (Received) 0
Ask one of your senior tech’s compressor probly has a device to stop it from running when MT LPC control
04. 26. 2011, 11:52 # 3
Join Date Apr 2011 Location Philadelphia Posts 7 Post Likes Likes (Given) 0 Likes (Received) 0 Dislikes (Given) 0 Dislikes (Received) 0
Ok thanks. I didn’t seem to notice any pressure controls on it though. Possibly internal? Although I always thought internal was just to protect for over current. But my assumptions don’t mean much ha.
04. 26. 2011, 11:56 # 4
Join Date Jul 2009 Location Kansas Posts 522 Post Likes Likes (Given) 0 Likes (Received) 27 Dislikes (Given) 0 Dislikes (Received) 0
If you wanna look good then find the leak
04. 27. 2011, 12:17 #5
Join Date Apr 2011 Location Philadelphia Posts 7 Post Likes Likes (Given) 0 Likes (Received) 0 Dislikes (Given) 0 Dislikes (Received) 0
Haha oh I’ll do that. I say not much knowledge but I can find leaks and get a system running great. I do that all the time. Apprentice specialty, that and coil cleaning, belt changing and filter changing. But I just never encountered a system with no refrigerant. I’m not asking just to look good, trying to learn the trade as well.
04. 27. 2011, 12:26 #6
Join Date Jul 2007 Location Delaware Posts 3,825 Post Likes Likes (Given) 0 Likes (Received) 2 Dislikes (Given) 0 Dislikes (Received) 0
Look down into the unit and see if you have a stub of copper on each the low and high side. If you have a low pressure cut off, the compressor will not run if it has no refrigerant in it.
Always here
04. 27. 2011, 12:55 #7
Join Date Apr 2011 Location Philadelphia Posts 7 Post Likes Likes (Given) 0 Likes (Received) 0 Dislikes (Given) 0 Dislikes (Received) 0
May sound stupid but Im not sure what you mean about the stub. Dont the cutoffs have contacts hooked up to the piping open or close depending on pressure? If that’s what you are talking about this unit did not have them. If not please explain haha. Thank you
04. 27. 2011, 01:08 #8
Join Date Jan 2009 Location Fairfield county Connecticuit Posts 803 Post Likes Likes (Given) 0 Likes (Received) 2 Dislikes (Given) 0 Dislikes (Received) 0
Last edited by Special-K; 04-27-2011 at 07:57 PM .
04. 27. 2011, 01:10 #9
Join Date Apr 2011 Location Philadelphia Posts 7 Post Likes Likes (Given) 0 Likes (Received) 0 Dislikes (Given) 0 Dislikes (Received) 0
Thank you. There were none of them on the unit .
04. 27. 2011, 01:11 #10
Join Date Jan 2009 Location Fairfield county Connecticuit Posts 803 Post Likes Likes (Given) 0 Likes (Received) 2 Dislikes (Given) 0 Dislikes (Received) 0
was the condenser fan running?
04. 27. 2011, 01:18 #11
Join Date Jul 2010 Location North Carolina Posts 119 Post Likes Likes (Given) 10 Likes (Received) 1 Dislikes (Given) 0 Dislikes (Received) 0
With it at Zero through nitrogen in it you will hear the leak. The reason it won’t start is as the other techs said Low Pressure Switch tripped most likely but now the system is open somewhere and moisture is inside so thats not good either. Hope its an easy fix for you
04. 27. 2011, 07:26 #12
Join Date Dec 2002 Location SouthEast NC ICW & Piedmont Foothills Posts 8,487 Post Likes Likes (Given) 101 Likes (Received) 300 Dislikes (Given) 1 Dislikes (Received) 0
1-amp draw of comp will let you know if it’s really running
2- did this thing have service valves on it?
It`s better to be silent and thought the fool; than speak and remove all doubt.
04. 27. 2011, 04:38 # 13
Join Date Apr 2011 Location Philadelphia Posts 7 Post Likes Likes (Given) 0 Likes (Received) 0 Dislikes (Given) 0 Dislikes (Received) 0
Fan was running and I did amp draw on comp and no amps. I did not notice any valves.
04. 27. 2011, 05:25 # 14
Join Date Aug 2007 Location Western Oregon Posts 499 Post Likes Likes (Given) 0 Likes (Received) 0 Dislikes (Given) 0 Dislikes (Received) 0
Push in on the compressor contactor momentarily, see if the compressor tries to start. Don’t hold it in, it doesn’t take long to hear LRA!
RealEyes
Realizovat
RealLies!
04. 27. 2011, 06:57 # 15
Join Date Feb 2011 Location Sacramento, CA Posts 148 Post Likes Likes (Given) 0 Likes (Received) 0 Dislikes (Given) 0 Dislikes (Received) 0
If you found the system flat on charge and the unit does not have any safety devices on it ( i.e. Low pressure cut out or a freeze stat), I would have to conclude that the compressor ran without referigerant in it. Did you ohm out the windings, or check for a winding that is shorted too ground? Compressors dont like running without oil, they wont last long. Your compressor probailly has an internal overload in it, but this is an auto-reset sefety, so when the compressor cooled down and the clicks-on closed the compressor started again. You could explain to your customer that you found the system flat and the compressor not running. Explain that you want to try too fix the leak first and then pull the system down in a vaccum and weigh in some referigerant and see what happens. I would also let him know that since the unit does not have any safeties in the system the compressor may have ran with no oil return. Hence the compressor may fail at anytime. I would also try too sell the customer on installing some low and high pressure safeties on that system. Good find though, you investaged the unit on your own and found out the basic information you needed too take care of this matter for your customer.
