Hello Mr George

submitted by /u/freshquivel [link] [comments]

Compressor starts and stops via control circuit

Before I even begin, I will articulate that we *will* call professionals next Monday, and that this post is for shards and gaggles in the sense that I may pursue a career in HVAC in the future, and I just like having an understanding of things

We have a legacy heatcraft freezer that stopped properly working after the boys downstairs turned it off via the breakers over the weekend to 'defrost' it. After the defrost, they flipped the breaker and the fridge turned on for about five minutes before it turned off. It will stay off for a while before coming on again and then repeat that. They called me down to look at it, as I am the general maintenance for the shop and because mgmt is a lil' cheap, I look at everything before pros are called.

I should stress that I believe I found a leak when they did this because sometime after shutoff, I saw bubbling from the output of the evaporator where severe frost had accumulated and the insulation was torn.

I looked at the schematic and using the limited knowledge that I have, was able to figure that it behaves like that because the contactor's coil becomes deenergized and it cuts power. There is a control transformer that takes two 480 phases and turns it into 240. One leg feeds directly to the first input of the contactor's coils while the other leg feeds two parallel circuits, which I assume are the control circuits. One branch goes from the transformer, to the LPS, to the HPS, to a thermoswitch, and finally to the other input of the contactor coil. The other branch goes to a solenoid, then to the poles of a current sensing relay (that reads one of the three phases going to the compressor), and finally back to the contactor coil.

During normal operation, I assume that the power flows unobstructed through the switches and completes the circuit, energizing the coil and actuating the coil. The Current Sensing Relay supposedly work off the EMF from the phase its monitoring and allows the solenoid to be energized.

So I am thinking that one of the switches detects a fault during operation and opens, disengaging the coil and cutting off power. After some time it "resets" and reenergizing the coil. I tried to isolate where this was coming from by probing the leads of each switch where i could to ground. The LPS output lead read 240 to ground but the HPS only read 40 to ground. The lead coming from the transformer to one of relays poles also reads 240 to ground.

Like I said, we are going to call our HVAC guys but I am posting because I enjoy electrical systems and I want to understand at least somewhat what is happening here.

I have a schematic if anyone is interested.

I have also stopped fucking with it as I do not want to mess anything up.

apologies in advance if this is dumbfuckery

submitted by /u/Potential_Aspect_486
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Might be why cases aren’t making suction

9psi drop across this filter on suction header. No case was below 2* on the whole LT rack. submitted by /u/MildSeraphim [link] [comments]

RDM Upgrade

Co2 Transcritical… Spent the last few days upgrading the original Carel iPro valve controller to an RDM. Lots of learning for me! The RDM runs a custom made program which operates the HPV & BGV much more efficiently. We can also log in remotely and see exactly what’s happening through trends. Anyone else out there use RDM? submitted by /u/DrunkenCactus [link] [comments]

certifications

Hi guys! What certifications and licenses do i need to advance my career in refrigeration and look more valuable to employers? i currently have my 608 and CARO certifications, but was curious as to what other certifications i can get to bolster my resume! thank you!

submitted by /u/BassGodSupreme
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Heacraft training

Anyone done any training at Heatcraft? Was is worth it?

submitted by /u/No_Negotiation_5537
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Inlet and outlet are combined.

I need some help. I’m on a ship and the refrigeration for the food storage has the same inlet and outlet. They both connect to one pipe. Wtf is going on.

submitted by /u/DVF2002
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Anti sweat heater Kysor Warren

Model QFGT-05AUN Serial C15K01763 At a store right now they have 2 of these 5 door cases side by side. One of them has no power to any of the defrost heaters and is causing lots of ice buildup around the door frames. I’ve been doing reading online and there should be a klixon to shut the heaters off during defrost but I can’t find the switch anywhere. I have looked both sides of the coil and I also saw somewhere to look behind the thermometer on the top panel of the case- no luck. Kysor is closed now so I can’t call tech support. Does anyone know where this klixon could be, or if there even is one?

submitted by /u/tylerosst4r
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Today’s supervisors

Surprisingly it wasn't their fault I was there today

submitted by /u/xoutercraw
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Poor guy

This restaurant I was at yesterday had some cute blankets for the condensers. What do y’all think? submitted by /u/hotrefrigeration [link] [comments]