Need help to identify parts and thier functions

Hello everyone, i have come across a walkin freezer at subway. Clients wants it temprature between -25c to -30c. Freezer was working fine till last week, when it started to drop its temprature they called a tec. I dont know what he did, but he said there was a leak he fixed it and charged the system with R404a. He left and said everything is fine and temprature will drop to -30c. Well this didnt happen what happen was short circuting in panel box wich damaged circuit breaker and magnet switch.

Anyway they called me now as there regular tec is not showing up. Quiet honestly i dont have prior expirience working with these freezers. I have replaced two circuitbreakers as i have them on me, i will be taking new magnit switch on monday, this will turn on my unit. Now the problem is that on compreser there are no labels indicating which refrigerant should be used. At subway they have a walkin cooler as well, so this walkin cooler have same system installed. Both compressors are same. At least they look same .the compressor installed on walkin cooler have labels and it says it R134a. What i am confused is this should i charge R134a. So far i am not able to verify which refrigerant i am suppose to use...

Any help is appreciated. Below are some pics attached.

Find the expansion valve the refrigerant used will be marked on the head of the valve,on your pictures one is a defrost timer and one is a delay timer,contractors are for compressor and defrost heaters.

Thank you so much, will look onto a expansion valve, in first picture we have a defrost timer??? If yes how long should be a defrost time?

It's a defrost timer and from your picture it's set for 5 defrosts in 24 hours which should be ok,

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Originally Posted by cadwaladr

It's a defrost timer and from your picture it's set for 5 defrosts in 24 hours which should be ok,

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thanks for the info, i haven't been to the site yet but once i will get there i will share more pics & info.

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Originally Posted by cadwaladr

It's a defrost timer and from your picture it's set for 5 defrosts in 24 hours which should be ok,

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Well i am at a site now, here are some pics, couldnt figure out the refrigerant as there are no lables, even on comprasor. I guess i have to charge R134a and see what it does. I am going to vaccum system then charge it.

Quick question, how much Amphere should it be taking.

Clean the condensor before you do anything,what temperature is the filter and does this unit have a high pressure switch .

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Originally Posted by cadwaladr

Clean the condensor before you do anything,what temperature is the filter and does this unit have a high pressure switch .

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This is what I have here. Also I have the system on vacuum for last 30 mins, but it's still not done. I am suspecting a leak.

I don't see a high pressure switch,but 134a is not a good gas for a freezer there must be a leak do you have oxygen free nitrogen to pressure test when you have found the leak then I would use 404a but remember this should be charged liquid not vapour,it needs a good clean around the condensor area.

I would change that filter drier for sure.

Do you have a picture of the expansion valve ?

Look like I have found a leakage. I put system on vacuum. But it didn't go through. So I opened up the indoor and find oil on these pipes, going to check & see if I am right or not.

I think this is what you are asking for.

The expansion valve is on your picture of the inside where you think the leakage is,it's the only valve there on the top of it where the sensing bulb joins the valve there should be the refrigerant number or if you cannot read it the sticker maybe coloured that would identify the refrigerant.

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Originally Posted by cadwaladr

The expansion valve is on your picture of the inside where you think the leakage is,it's the only valve there on the top of it where the sensing bulb joins the valve there should be the refrigerant number or if you cannot read it the sticker maybe coloured that would identify the refrigerant.

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Thanks for being patience with me, i am very thankful. its been a wonderfull learning expirience so far. I am back now will visit the site tmrw & have a brief look on a expansion valve.

I am going to take nitrogen cylinder with me, bcuz i tried giving pressure using my vaccum pump but it didnt work out, gauge hardly went out to 40PSI. I didnt get it, what was the issue. Can you guide me, Thanks.

Pressurise the system to 100 psi ,use soap washing up liquid put it on where you think the leakage may be and you should see bubbles,you may even hear it,do not go any higher than 250 psi ,repair the leak vent off the nitrogen change the filter drier and recharge it,have you looked at the expansion valve yet?.

I got back home now, I will be visiting site this evening, will look up expansion valve and let you know.

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Originally Posted by cadwaladr

Pressurise the system to 100 psi ,use soap washing up liquid put it on where you think the leakage may be and you should see bubbles,you may even hear it,do not go any higher than 250 psi ,repair the leak vent off the nitrogen change the filter drier and recharge it,have you looked at the expansion valve yet?.

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I pressurized the system to 150psi, no leaks. Left it there for two hrs to make sure, then I let it vent out the nitrogen self vaccum the system and then charged it with the refrigerant.

Btw I checked the expansion valve it said 404 & 507.

Question. How can I make sure that my compressor is working right, by that I mean compressor pump is fine. Should I check the discharge pressure on high pressure gauge???

Yes you need to check head pressure ,it should he around 250 psi remember to charge with liquid it has a sight glass so that should be full when fully charged,and change the filter drier clean the condensor and you should be OK,

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Originally Posted by cadwaladr

Yes you need to check head pressure ,it should he around 250 psi remember to charge with liquid it has a sight glass so that should be full when fully charged,and change the filter drier clean the condensor and you should be OK,

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Well, everything went right. I charge the system with 404a watched sight glass, first it showed bubbles then showed liquid. Temperature started to drop as well to -6 it took about 4lbs of refrigerant... I was running low on refrigerant, as sight glass was not full of liquid, it was clear. I told my apprentice to shut off charging valve and remove charging hose, I was thinking let see how much temperature will drop. Meanwhile I will buy more refrigerant as well. GUESS what it was just a learning experience, the moment my apprentice shut off the charging valve and removed hose all of a sudden charging line started to suck air, as it was not properly closed, he quickly try to reconnect the hose but it was too late by then, temp dropped all of sudden, amphere dropped from 8 to 3.4. Well we find out now that charging line valve is faulty. Can't do much about it. Have to vent off all the refrigerant again and charge it back on.


I am planning to take about 8lbs of R404a today. Should that would be enough? Secondly to see if system is fully charge the sight glass must be full of liquid?
3rdly if we aren't able to achieve -30c then what should I do. Probably go for a compressor replacement?

Not sure how much refrigerant you will need,but if you had positive pressure with the faulty charging line do not worry,did you carry out all my advice about filter and cleaning condensor?,if this freezer has lost temperature it may take a couple of days to recover,what is your head/delivery pressure and the ambient temperature at the premises ?

Yes the sight glass should be full.

Well, went today and charged the freezer with Liquid R404a. cant freaking believe, it took about 5kgs approximately 11 lbs, but still sight glass was not full, it was empty you can say, it showed bubbles & liquid when being charged.
After running for 4 to 5 hrs, temp dropped to -9c. i am hopping by morning it will be around -20c or so.

debating to take more refrigerant as you said sight glass must be full. so Far condensing is super-awesome and return aka suction is in full vapors.

It's going to take time to cool down the room because it has been faulty,I would not add any more refrigerant ,what temperature is the liquid line the drier etc.

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Originally Posted by cadwaladr

It's going to take time to cool down the room because it has been faulty,I would not add any more refrigerant ,what temperature is the liquid line the drier etc.

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About temp yes we have to wait atleast 24hrs. About refrigerant I think I thought to wait & see what it does.

Regarding condensing temperature I have to say I don't carry digital temp detectors. Also I don't know about the heating & cooling temp. Need to learn.

It sounds to me that you learn quick! For some reason I thought a lot of equipment in the your part of the world was still using r22 ?

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Originally Posted by cadwaladr

It sounds to me that you learn quick! For some reason I thought a lot of equipment in the your part of the world was still using r22 ?

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Yes mostly split system use R22, but not in commercial use.

Quick update on Freezer, it's back to 2c & 3c. Dropped from -9c. Can't get it. May be a faulty comp or need more refrigerant charge.

Sounds like you have a leak,it should not lose temperature as quick as that look at the sight glass is it the same as yesterday if not you need to locate the leakage

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Originally Posted by cadwaladr

Sounds like you have a leak,it should not lose temperature as quick as that look at the sight glass is it the same as yesterday if not you need to locate the leakage

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Well yesterday sight glass was showing nothing it was clear, it only showed liquid when it was charged. Secondly I charge the system using suction line as picture attached. It has a valve to close the supposed charging line but when we try to close it it will closed the suction line resulting in temp drop and comp heating up. It was obvious that whole suction line is being closed.
What I did was leave that valve open and closed the outlet where my charging line was with a dead nut. I am going to see & check if that's where a leak is. Bcuz I pressurized the system with 150psi nitrogen & it stood still.

A clear & close up picture of valve.

just visited the site, Comp was not working, it was super heated............ try to cool it down but it dint started, probable cause, over charging of Refrigerant, thats what comes to my mind..... connected my charging line to check the pressure but when i tried to open the valve it just says no. it dont wana open. unfortunately i didn't had grip-plier in my bag, going to loose some refrigerant & see what it does. if you want me to take Condenser Reading while condensing and evaporator reading i can take it for ya. this thing is getting on my nerves now. deciding to change comp.