walk in freezer wont drop under 20 degrees

I have a problem on a low temp 404A walk in freezer; it won’t drop UNDER 20 degrees. This condensing unit is under the buildings roof and above a drop ceiling on the box top in a space that is 120 degree's; ALSO THE CONDENSER FAN IS 6 INCHES FROM THE BACK WALL! When you open the main door to the case, the evap is on the left side of the box and NOT to the rear of the freezer.

However the owner @ this Chinese rest. Swears it was @ 0 degrees in the summer, last year here. I don’t believe her; not with this poorly designed box.

I have never a walk in freezer designed so poorly. The condensing unit should be at least an equal length of it's length away from the wall and the condensing unit should be on the roof of the building; only 6 more feet higher.

The TX; it is external EQ. and one of the circuits was starved; I have a sight glass on the liquid line past the receiver which is a Parker 5" diameter X 10" high = 6Lbs X .09 for R 404A = a good place to start after recovery was done.

2 AC companies were there before me and could not work a king valve and dumped a whole 30lb virgin tank of 404A in to the room when they removed their gauges over and over again. They were all over that TX and even hacked up the stem with pliers.

So at the TX , I finally opened the starved circuit and then I THINK the tonnage is wrong on this TX. The box is 6' X 5' 2" and SURE I checked for leaks at the seals, I checked for excessive frost and ice = none.

So after recharging; I then shortened the defrost time to from 15 minutes to 10 minutes because all 3 heaters were working fine and I cycled it and 10 minutes melted everything down = the same problem…………………20 degree’s.

I then increased the defrost time to 30 and then 40 minutes so the termination switch would end the defrost cycle to make sure the clock was not = same problem, wont drop under 20! The door gasket is fine.

Also they changed the Sporland dryer for the old type Emerson "BB filter" which is fine.......... I prefer the solid sporland core though. At first the superheat at the compressor was 12.

I have a low suction at the evap ( -40 degrees ), but an unusually high superheat / suction at the compressor after I adjusted the TX to feed the starved circuit. So again I removed 10oz of refrigerant to make sure there was no liquid at the compressor suction. I noticed my low gauge was erratic when at the evaporator.

Now the superheat at the compressor is at 20 which is Copeland’s max.......... but again it was 12 before I moved the TX stem = SOMETHING I NEVER DO = never had to do! and now again one of the circuits is starved…………. But the other 2 are cold as they can be and look great. I figure I am operating @ 2/3 capacity here and just wanted to get some idea’s from you guys. I feel the TX is bad, I think they didn’t “heat sink” it with a wet rag when they soldered it in.

The superheat at the evap shows high because I can't get a temp clamp on this evap right = no room, so I tried my Fieldpiece K-TYPE thermocouple wire which is the yellow sensor with the velcro ZIP;
I am worried that IF I change the TX; I might have the same problem because of the excessive heat in the space where the condensing unit is and because the condensing unit is so close to the wall.

What do you guys think?

Moisture in the system that freezes in the TEV, distributor, distributor lines?
Debris in the same components as mentioned above?
You have to measure every bend on your evaporator and see if all the circuits are injected equally.
If one circuit injects too much, then the TEV will close due to this too small SH, shutting down all the other circuits.
Meshfilter in the compressor clogged?
What's the LP measured at the evaporator if you have the possibility to check it there?

Og , I forgot, never believe (all) what a customer is saying, pick out the things out of their story that can be true and fits in your theory what can be wrong but rely only your own measurements.

First this is why AC techs should work on AC systems unless properly trained in the fundamentals and operation of refrigeration equipment. They know their jobs as we know ours. The pliers damage on the TXV stem is nothing new. But even AC techs carry service wrenches. Anyway, this is how I handle any job I come into where I cannot identify EXACTLY what was done before me. Size the TXV by evap model number [ tonnage ] and verify it against condenser specs. If all is ok, change the TXV, using any style..flare or sweat..you're happy with. I never..ever..play with the setting unless I have another factory set part on hand. Techs argue the point but they never seem to return to exact setting or stay there. Don't know how old system is but if it is old enough to have run this long..don't sweat the condenser positioning. It's not great but it has run this long. Add'l ventilation would help if possible. If it is the lower [ bottom ] pass of evap coil not cooling you may have oil trapped in line passes. If and when you change TXV and dryer. blow out with nitrogen. Also AC techs don't usually carry R404 as a rule. Don't be surprised if the charge is a drop-in..hot shot or flavor of the day. Recharge with what you know is right and start from there. You can't guess what someone else did or didn't do. You're responsible for what you leave them with. That's where you start. Good luck !! Let us know what you end up doing so we all learn something new. Have a good day.

hi deniver45,

what was the condensing unit and evaporator unit model? have you check the system is it still right for the room? because as per owner it can reach 0 degree is this Celsius or Farenheit? 0 F = - 17 C , - 20 F = - 28 C. there's already a big gap between the two temperature without considering the evaporating temp.


thank you

lynark

Thanks for all your input as I know how busy all you guys are; in fact you are all right. But here is the thing. It can NOT be done period! This freezer will NOT drop to 0 or even 10 in the space where the condenser is @ 120 degree’s according to the tables / so says Copeland.............. It's as simple as that! I am loosing 17,000 BTU on a 1 ton system = I am working at HALF capacity. SURE in the fall and in the winter it will, but “no way hose’ in this heat. = $HIT!

IT HAS TO BE MOVED TO THE ROOF = PERIOD! Did I mention here in SC the heat index is 105 degrees?

What should I do about the FRICKING (are we allowed to say FUKK here on RE ?) LYING SACK OF $HIT CHINESE lady as she assumed that IF I could NOT get her freezer down to 0, then I would walk away and leave 7 LBS of R404a in her system as well as a new run cap? DID SHE REALLY THINK I COULD BE ROLLED OVER LIKE THAT?

I’m sorry if some of you feel u wasted your time; but hopefully ( I know I did) we learned something here. Anyone who says they know EVERYTHING in this business is kidding themselves. Yesterday I went to CC ****son with the model number to the Condensing unit. I asked if the AC company that worked on it was a reputable AC dealer and was told they were; I fact I spoke to the receptionist there yesterday and she was kind enough to tell me everything they bought as well as CC ****son. I go to CC ****son because they usually have everything I need and the guys behind the counter are going be us in 20 years. They KNOW the business. CHINA says AC company did NOT charge her and now I find out they paid wholesale on the evaporator. China says it was down to 0 last summer, AC says “we walked away”, we didn’t know what else to do!

Last year in July on the 1st, a NEW Chandler evaporator was purchased = MATCHED TO HER CONDENSING UNIT. There is one thing they did NOT buy. The heart of the system = TX / TEV. They used the old one on a brand new Chandler condenser matched up perfectly to it’s Copeland mother upstairs. They played with the wires on the terminal board though and moved some wires maybe because the fan was in defrost and they simply moved it to a terminal that was hot. I am a FIRM believer = NEVER EVER touch the TX / TEV adjustment UNLESS it is used, or someone else moved it first… and I agree with “FIESTY”, that it will NEVER get back to the original adjustment because now a LOAD is on that spring.

I have always said this is a “thinking man’s game” and if you not a sharp guy, then stop playing the game. I thought and told “China Lady” ( FRICKIN LIAR ) ………..where could the heat go in a space of 120 degrees? BUT SHE INSISTED IT WORKED AT 0… And I asked “even in the summer?” She whole heartedly agreed, YES in the summer. NOW I find out it was 10. I SO laid into her last night. AND I told her we are going to fix this right, or you can pay me the $800 you owe me and we’ll leave it like this. She says I didn’t fix it, BUT I did. I got it RIGHT BACK to where it was last summer = 20 degree’s. Remember when I got to it, it was dead in the water. NO refrigerant in it, with a blown start cap.

CHINA is there right now at 9:12 getting a load of frozen goods! Jonathan next door ( also my customer ) has NO MORE ROOM in his freezer. We live in a 50, 000 county and she has been blacklisted. You know I actually feel BAD for CHINA because of the way she is?

DO YOU FRICKING BELIVE THAT?

There are people like that the world over sadly, and sometime we find ourselves working for them.
What gets me is often i have a gut feeling of what they are like and will be like come payment time but i don't like to say to a new customer "You seem dodgy, call someone else!" I've been known to leave a warning for the next company in permanent maker to get payment before leaving site etc :D

Luckily we get on well with a few local fridge companies so we tend to give them a call to see if they know anything about customers we have suspicions of.

These are the customers hacks were invented for!

Does anyone know a good thermocouple with a SMALL 1/8th clamp to do superheat readings at the evaporator? I know the guys at Fieldpiece and have been riding them for one, they say there is one in the works. That small yellow wire they have ( ATB1 I think ! ) is a pain with the black velcro wrap it comes with.

OR is anyone using an IR thermometer to do superheat reads? I heard one must wrap the tube with black tape, then dry it so the beam won't bounce off!

Guys,

It was the TXV = too big, wrong tonnage, I think I said it was "hunting" above where the low gauge dial @ the evap suction is eratic. First starved and then flooded. ALSO after I wrote the post, the weather changed from a High of 105 heat index( 90 at 9 AM ) to a high of 90, then 84 as a high and it rained all week, she is pissed because I flushed her system with refrigerant! We did that years ago, and when an AC guy comes and dumps 410a in there, why used QUICK FLUSH in a tight space ( $53) where you can't breather over the extra ($100 for the refrigerant over the QF for $53 ). After all, there is no compressor burn out here! ...no acid problem, ALSO the AC guy jacked the high pressure nipple on the dual pressure switch SO HARD to the unit's high side, I had to take a tap, and dye to fix that = was leaking, but not that bad.

"never assume it is only one problem"

I am a pensioner after working for 40 years in the field.I teach now for my government on programmes for new /young people in the industry.The very first thing I teach is that all and I mean all customers are liars.So do what you think is right to do,tell the owner the expenses and walk away.Let him call you.....

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Originally Posted by coolaircyprus

I am a pensioner after working for 40 years in the field.I teach now for my government on programmes for new /young people in the industry.The very first thing I teach is that all and I mean all customers are liars.So do what you think is right to do,tell the owner the expenses and walk away.Let him call you.....

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I often find that not only do you have to diagnose the system but also to diagnose the customer too to find out what the problems is...

Had one recently that said "I haven't had the cover off" Looked at the cover and could see he had cross threaded one of the bolts again, the same one i spent a few minutes taping a clean thread back in and copper greasing on the last call :confused:

Jon :)

I think your problem is the txv.