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reach-in drink cooler

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orlandotech

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Discussion starter · #1 ·
I know you guys are going to rip on me for not knowing much info on the equipment but here goes.

I am normally a resi and commercial service tech / installer but we are kinda taking refrigeration calls from people we know. I have set up and comissioned a few 404a and 22 walk-in coolers and freezers with success in the recent past so I'm getting the hang of this type of work. I'm trying to learn this aspect of our trade by lurking in here and reading any books/ literature I can get my hands on so please understand I'm not an expert, maybe mid level experience.

Anyway I got a call from this guy that has a small reach-in drink cooler that he says is not cooling as good as it used to. this cooler is located in a concession stand at a local little league ballfield so I don't think it could be too big. I was wondering if there is anything I need to look at right away when I get there to rule out the obvious ( dirty condenser/ evap coils, liquid line temp, suction temp, etc.. ) I'm pretty sure that on small systems like that you can't attempt to attach guages due to the small charge in the system. any thoughts or suggestions would be helpful.

also, are there any good books besides "modedrn air conditioning and refrigeration" out there for me to read and learn from? I am having to learn on my own. my boss has mentioned in the past about sending me to school ( as an A/C tech ) but since I've gotten a lot better, he doesn't think I really need to go now ( his words ). I feel like I'm missing something by not going and the " school of hard knocks " or " field experience " method is a slow process.

thanks in advance
kevin
 
#2 ·
Start with the simple stuff like the temp control. Make sure the system isn't shutting down prematurely on temp.

You're dead on with checking condenser coil/fan and evap. Also verify that the evap coil isn't partially froze up.

You really should put a set of gauges on the unit if it has taps. I suggest you use quick connects and preferably shorter hoses.

If there are no taps, you may want to think about brazing a couple on. Hi/Lo pressures will tell you alot about what is happening.

Good Luck
 
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Discussion starter · #3 ·
markettech said:
Start with the simple stuff like the temp control. Make sure the system isn't shutting down prematurely on temp.

You're dead on with checking condenser coil/fan and evap. Also verify that the evap coil isn't partially froze up.

You really should put a set of gauges on the unit if it has taps. I suggest you use quick connects and preferably shorter hoses.

If there are no taps, you may want to think about brazing a couple on. Hi/Lo pressures will tell you alot about what is happening.

Good Luck
Click to expand...
thanks markettech. since you mentioned premature shutdown, I've come across that before when doing startups on walk-in freezers/ coolers where I would set the T-stat to a certain temp but the unit would cycle normally at a higher temp like I had set to that temp. say I would set a cooler to 35 and it would cycle at 40 to 42 or something like that. are the t-stats ( honeywell ) that far out of calibration normally or am I missing something? other than that the system seemed to work good.
 
#4 ·
T-stats can be out of calibration. I usually look at the numbers on the stat just to get me close and adjust based on actual temp.

Not sure how up to speed you are on refr so I will mention this: Most likely this cooler is controlled by a constant cut-in t-stat. This means that you will be able to adjust the temp colder, but once the system shuts down, a preset temp will need to be reached before the compressor comes back on ( usually +38F to +41F depending on the actual stat).
 
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#5 ·
If a guy knows what flavor rfgt, what target temp, and has a PT Chart in his pocket, it's sometimes possible to get a diagnoses with temp readings at various points without attaching gages. This is NOT the preferred method. As Markettech said, taps and SHORT hoses are the way to go. But on smaller systems, full charge weighed in in ounces, you are smart to be concerned. Buy a laser or ir temp gun.
 
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#6 ·
engineerdave said:
Buy a laser or ir temp gun.
Click to expand...
Not to hi-jack the thread, but I have never had good luck with those temp guns. Seems like (for me anyway) they'll get ya in the ballpark but not dead on.
 
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#7 ·
Definitely NOT preferred. Nothing beats gages. But it can get a guy through in a pinch.
 
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Discussion starter · #8 ·
engineerdave said:
If a guy knows what flavor rfgt, what target temp, and has a PT Chart in his pocket, it's sometimes possible to get a diagnoses with temp readings at various points without attaching gages. This is NOT the preferred method. As Markettech said, taps and SHORT hoses are the way to go. But on smaller systems, full charge weighed in in ounces, you are smart to be concerned. Buy a laser or ir temp gun.
Click to expand...
I have a fieldpiece hs35 with a pipe clamp type temp probe. will that work or will there be space constraints in the bottom where i won't be able to use it?

I do have a cheapie 410a manifold that had really short hoses so maybe I could use those with the low loss fittings I have.
 
#9 ·
If you're at all able to use gages, use them. As for your clamp, the more data you get for yourself the better.
 
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#11 ·
markettech said:
Start with the simple stuff like the temp control. Make sure the system isn't shutting down prematurely on temp.

You're dead on with checking condenser coil/fan and evap. Also verify that the evap coil isn't partially froze up.

You really should put a set of gauges on the unit if it has taps. I suggest you use quick connects and preferably shorter hoses.

If there are no taps, you may want to think about brazing a couple on. Hi/Lo pressures will tell you a lot about what is happening.

Good Luck
Click to expand...
Yep he has some good answers.



Also
check the air curtain , this at the top front of the cabinet

Make sure the velocity from this is correct to stop outside air entering the cabinet.
Check to see if the cabinet is positioned correct and that ambient air is not blowing straight into the cooler.


Check the temp display control on the front of the cabinet to see what temp it reads , this should be the air temp leaving the coil.
check the air temp at the air curtain , there should be around an , 8 k temp difference between the display and the air curtain.


Put a meter in the cooler to make sure it cycles between ,
0 - 5 degrees Celsius , drinks should be kept between this range.

Make sure cabinet is loaded correct 25mm ( + , - 5mm ) between rows of product to allow for proper airflow.
Stock should be rotated , old at front , new at back.

Make sure product is not placed in cabinet hot , open deck cabinets are not for cooling product , they are only meant to maintain the product at the set temp they entered.

Contact manufacture for the access code to the display to allow entry to the parameters , and alarm log to see if there was a problem.
 
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#12 ·
engineerdave said:
As Markettech said, taps and SHORT hoses are the way to go. But on smaller systems, full charge weighed in in ounces,
Click to expand...
couldn't have been said better try filling a 3' hose with liquid a couple times on a system that takes 14oz and see how long it works!! you'll be in trouble! but if you have to use a hose atlease try to use a check valve or shut off valve on your high side hose to recover the liquid back to the low side(make sure manifold and hoses are purged of air though)

I don't know if your 410a gauges will be that good to use because it's good chances that you'll be working with R-12/R-134a(or equiv) on a cap tube system and your suction is going to be low and usefully readable on a 410a scale gauge.

I have a handly little set of gauges I made up for troubleshooting captube systems, ice machines and other critically charged equipment, handy to have on hand, just little fittings put on a regular set of gauges that will let you attach them to service ports easily!

-Mike

Image
 
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#13 ·
This is my set-up. Got one for checking oil pressure, suction, and discharge. All have quick connects. The short hose and shut off gives me a little bit of wiggle room in tight spots
Image
 
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#14 ·
Hey Mike looks like itstime to re-zero your gauges. you can purchase these gauges from yellow Jacket Already set up as you show them.. I use a similar set up when servicing racks,for checking compressor oil pressure and for seting up condensor fan cycling controls. saves from having several sets of gauges all over the place.
 
Discussion starter · #15 ·
thanks guys. I thought of doing something like that squires but I don't have time to make up something right now. I'm going to go over there tomorrow and at least check it out. I use the same kind of ballwhip markettech but I use it for my micron guage to protect the sensor from pressure when I juice a system up. I'll try to let you guys know how it goes.
 
#16 ·
I think the problem with this system can be found before , even putting a set of gauges on.



Am i wrong ?
 
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#18 ·
*

check all obvious things first,then;

dont be in such a rush to put gauges on, if the charge is
correct, you dont want to make it short on charge by putting
your gauges on, especially on a critically charged small
system ,when i get to a system with or with out access ports
i will feel the loops on the side of the condenser coil and
make sure they are warm all the way down.

if i cant eliminate a (refrigeration problem) i would at that time
put gauges on or install ports to access the refrigerant circuit,
the best type of port if needed to install is one that is brazed on
otherwise them (screw on and peirce) access ports will leak!



.
 
Discussion starter · #19 ·
well.....

i was on my way over there to look at it so I called the cust so he could let me in, he tells me that he had someone else from another mech. co. look at it yesterday because they got to shooting the sh*t ( he knows the guy kinda good ) and he mentioned the problem to him. the other guy happened to have a tech in the area. Where was the phone call saying that you got it handled Mr. d*ckhead? ohh well. he told me the other tech found the cond. coil filthy and there was some wire that was on the wrong terminal? bummer. I probably would have been fine looking at it since it sounded like an easy fix.

Thanks again for all the help and good advice even though I didn't get to use it. By the way, I asked in my orig. post about good books/ literature on this stuff. do you guys have any suggestions?
 
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orlandotech
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