So, I'm a newer HVAC tech. Less than 5 years. I have 20 years in the industry but only a little hands on, less than 10 years. The first 5ish years was install only, so new stuff and everything was neat and clean. Then a start up tech would show up and do the heavy lifting. Today, I relocated a condenser from one side of a house to the other. Ruud 4 ton heat pump. Ran a whole new lineset, customer had power pulled to the new location, I landed thermostat wire in furnace and in condenser. Nitro leak test (good), purge while burning. Wired it all up, and turned it on. Compressor ran for about 20 minutes, then shut off but outdoor fan motor stayed on. Defrost board indicates nothing is wrong (Roll eyes) but the compressor won't come back on . I had to leave for other customers, will be back Friday. What I can say is the vapor pressure is low... Like 50 psi when the compressor was running. Liquid pressure was 230ish. But the compressor won't come back on, and I haven't troubleshoot anything as of yet. My question to you experts ( we have a couple on the board way more experienced than me) is what should I start looking at? Electrical like cap/contactor? Bad wiring by me at furnace or outdoor? Low pressure lockout? Just curious where to begin. The furnace is in a nightmare location but I plan to go up and double check my wiring anyway in the attic. Thanks in advance.
That's interesting. I'm assuming 410A, so it seems really low on charge. My initial thought was a low pressure cut off, but in most units, the condenser fan is powered on with the compressor. Even if there's a head pressure controller, it will be downstream of the contactor, so the compressor can run without the fan, but not the other way around. That's a generality, so verify that the same contactor powers the fan and compressor. I was a Rheem dealer for like 15 years, and my shitty memory can't recall if the heat pump boards separate the motors. Were you looking at your gauges when the compressor shut down? Is it possible that you have a restriction and the suction pressure dropped when you lost the compressor? It would normally come back on when pressures equalized, but there could be a lockout period. We have a different issue if this is a basic analog system with a contactor, HPCO, and reversing valve. In that case I'm looking for a weak capacitor, open thermal overload on the compressor motor, or a simple wiring issue.
Correct, 410A. It has a low and high pressure cutoff, so I don't know if that means it is not a "basic" system. I was looking at my gauges and the low side rose up gradually after compressor shut down, until equalization. Fan kept running the whole time.
Wow sounds just like my stupid Trane....Tech tried a hard start kit? It was locked up tighter than a drum and wouldn't budge.
It would be unusual for the compressor to stall after running for 20 minutes, but it could happen. Check your amp draw when you go back. If it climbs while the system is running, a hard start kit could keep it going, but it's not long for the world at that point. Is there a circuit board in the unit besides the defrost board? Is it an ECM or PSC fan motor? Typical contactor? Two pole or 1 + shunt?
Remember this is a relocated unit, aka used. I wonder if the replacement refrigerant charge was short on lubricity and the compressor had a seizure?
I'll get answers to all these tomorrow, not that I expect you to check the board on the holiday. I'm only going because I hate the idea of leaving this without investigating and figuring it out before the weekend.
It is possible, for sure, however I pulled the refrigerant into the condenser before relocating so it wasn't truly a replacement reefer charge... But i appreciate the thought.
Only a defrost board in the condenser. Amp draw on the compressor was fine this morning, it kicked right on and started cooling. WTF! PSC fan motor. still low pressure on suction line so im gonna trace it for restrictions. my helper ran it through the attic.
It’s a myth that refrigerant contains oil. Those jugs just contain refrigerant. The oil is added separately. It takes a bizarre set of circumstances to run it low, but I like where your head's at. It got me thinking. Being low on oil is unlikely, but an option could be a kinked line set, preventing the oil from traveling back to the compressor, which @socalrider eluded to. I've also seen big semi-hermetic compressors run low on charge and push all the oil into the coil if it's lower than the compressor. However, I've never seen it on a residential unit.
Ok who knows what brand of AC this is? Exterior sticker totally faded. The big numbers at the top of the sticker (model number?) says: 1296E13345 The condenser fan started squealing and trying to figure out if I can replace it and kick the can for another year or two. Heres the outside
The further you kick that can, the more it’s going to cost. I replaced all my stuff for about 10K about 5 years ago…it’s probably 20K now.
Yes, you most definitely can replace the condenser fan motor. I just did mine on my 40 year old system. You really don't need to know the make/model of your system, just the basic specs of the motor itself. Shaft size/length/motor frame/horsepower/rpm/voltage/direction of rotation. (Usually on label on motor) They are generally an "industry standard" size. Check eBay, as motor prices can vary considerably. I found a new surplus motor for $50, but they generally vary from $200-700. Yes, that's a big difference. Most industrial supply houses have them. Grainger etc. I upgraded the horsepower, cause I could. Like from 1/3 to 1/2. Also consider replacing the capacitor(s), if the system is old. $15-30. Info usually printed/stamped right on the capacitor. Whew, long run-on paragraph.
I just took a look at the fan motor. The writing is legible with some GE part numbers on it. Ill have to pull the fan cover off to read all of it.
Motor is a GE 5KCP39EG S070 S. Plenty of aftermarket replacements available. Thankfully theres only another 3 hot days in the forecast!
My guess would be I.C.P. based on the shape of the faded sticker. International comfort products, aka Carrier. Make sure you match rpm, HP, and rotation obviously, however brand name won't matter. There will be 5-10 options for replacement motors. New motor will need a new capacitor. If you can't get a dual run that meets your size, you can keep the compressor cap and just add the fan cap with a little extra wiring.
