# Diagnostic Help - Old R-12 Walk-in Cooler



## David40 (Aug 1, 2011)

Just wanted to get some opinions on diagnosing an old R-12 Walk-in cooler running 416a. Not pulling down the temp to an acceptable level.

Here are the operating parameters available to work with.
- System is air defrost only, TXV metering.
- Condenser and Evap are unobstructed, air flow looks good.
- Liq pressure 175lb, Saturation temp 130 degrees, Liq line temp 148 degrees. (Yikes Hot! -18 sub-cooling???)
- Suct line Pressure 20, Saturation temp 30 degrees, Suct line temp 59 degrees
- Condenser Ambient 90 degrees, outlet temp 110 degrees, = 20 degrees heat rise 

What's your guess as to what is ailing this system? ( besides being obsolete )
How would you proceed?

Would love to here the suggestions/ideas from the community.

Thanks


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## beenthere (May 30, 2009)

Make sure the condenser fan is spinning the right way. The problem seems to be in/at the condenser, since your not condensing.


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## David40 (Aug 1, 2011)

Thanks, I will double check that today. Note that it is condensing a little bit with a 20 degree heat rise from ambient, I would normally expect it to be around 30.


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## coolingitrite (Oct 10, 2013)

just wondering what happened with this with the higher subcooling and superheat together, sounds like it could be a improperly sized txv or other problem with the txv maybe a defective3 power head


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## David40 (Aug 1, 2011)

After having tried everything including manually adjusting the TXV I have determined the condenser is just too small. The evap is rated at 7,000 to 10,000 btu's being driven by a 6,500 btu condenser. It may have done a marginal/acceptable job when the coil was new but it just can't cut it anymore, especially with the heavy usage I have observed. Currently looking for a used 10,000 btu condenser for it.


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## coolingitrite (Oct 10, 2013)

So u are running a 3/4 ton condensing unit?

What about installing a one horse power condensing unit 404a and new txv. Put it to bed. 

Figure a 1hp condensing unit should give you around 9100 btus at 25coil


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## David40 (Aug 1, 2011)

Yep, that's the plan, only I don't really care what gas I use, R12, 134a, 404a.... I can still get a new R-12 condenser, and since I still have a jug of R12, I'd just as soon do that and keep the old valve.


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## coolingitrite (Oct 10, 2013)

I would still l go with the 404. Reason being a valve is not that expensive and since nobody has r12 anymore, I would switch it to refrigerant that is readily available and that works good in a medium tempo situation and save the 12 for somebody's car. Because if you spring a leak, and run out of 12 you'll have to use like 409a orr hot shot which I think are crap. Like I said a valve is not that expensive and you might be able just to replace the power head especially if its balanced port. Jmo


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## David40 (Aug 1, 2011)

That is a good point for down the road. Thing is this guy is so cheap he is making me look for something used, and I can't find anything. He may just let it limp along till the health department shuts him down. Another option I may get him to consider is replacing just the coil or adding a second one.


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## coolingitrite (Oct 10, 2013)

man, sounds like you are only engaged to this this thing getting ready to marry it.....lol... been there and done that so I get it... trying to stay busy and keep the money flowing.. I would think adding a second evap gonna cost ya more in the long run. you can find him a used condensing unit but make sure you have him sign ur invoice stating you offer no warranty. what area you at..io might be able to hook you up with a company that has used equipment. have you dealt with this guy for a long time. sounds like the kind of guy once he sees you are willing to band aid it or go against what u believe you should do, he will always expect the same. eventually, hopefully you will be able to dump him...good luck bro


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## coolingitrite (Oct 10, 2013)

1-888-661-0871

sells used equip with warranties.  located somewhere in wi.......says they ship


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## David40 (Aug 1, 2011)

Thanks for sympathizing. I was actually talking about changing or adding a new condenser coil. A friend of mine told me to just add a new coil right in front of the old one and pipe it in series with it. The thing did work for 25 years and the only thing I can find that has changed is the coil not removing the heat anymore.


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## beenthere (May 30, 2009)

David40 said:


> That is a good point for down the road. Thing is this guy is so cheap he is making me look for something used, and I can't find anything. He may just let it limp along till the health department shuts him down. Another option I may get him to consider is replacing just the coil or adding a second one.



If he's cheap. Just remind him that R12 will cost him $100.00 a pound. Then he may decide to go with a new R404A unit.


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## airtrackinc (Feb 12, 2014)

Moisture from the air freezes onto the evaporator coils (the cooling coils in the freezer) and forms an insulating barrier to heat transfer

The condenser coil of the refrigeration system removes heat from the system. It’s not unusual


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## ShepherdEHC (Feb 11, 2016)

I say change out the condenser to the right size that is needed. If its undersized then efficiency is off for compressor. May save servicing, and also if the unit has been running for so long maybe fixing the Air conditioner condenser size will give it another good run.


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