ice cream truck freezer

[GaryC]

Hi, , pretty down right now. My wife and I have an ice cream/concessions truck with 3 state contracts to provide food,ice cream,snacks,etc. at area beaches. The freezer we bought in 1999 from All Star Carts and Vehicles in Bayshore, Long Island,NY.
A TF40,3 door freezer. When we first bought it after a nightly charge being plugged in we'll get -20 degrees up until this year when I first plugged her in for the season we got -10. Then we just had some extremely hot and humid weather and the freezer would not get below 0. We had one guy come who gave it a charge with r-12 and then saying he was looking for leaks got into the freezer box itself and bent a copper tube and cracked it causing the r-12 to drain out into my freezer full of ice cream. He then tried to charge me for the refridgerant he lost and said he would come back the next day. I said I would pay when the job was done. Well he took off leaving me with a hissing leaking freezer and my wife and I rushing to get the product out of the truck and into our house freezer. I sucked in some of the r-12 pretty close to passing out.
The next day after calling around we finally got another tech to come over. He braised the cracked line and put in r409A. We tried charging it overnight again but it would never hit 0. We called him again .He came back and drained the refrigderant,checked for leaks (none found)and then put in mp66. We have charged it again overnight and its still only down to 0.
We need to have at least -15 to be able to sell all day keeping the ice cream solid, esspecially in july and aug. I'm at the mercy of these guys and don't know what to do. Any ideas? Only thing i can remember is he stated he checked the compressor by closing one side and it pulled a hair under 10 which he said was okay. I'm lost cause I have no idea.
I'm already out 300 dollars. Should he have put a new drier/filter making the change from r-12 to 409a,and then to mp66. I'm in a bad way right now. Anything that could help would be greatlt appreciated. Thanks Gary and Anabela

[Yusuf Ismail]

Hi
Tell, Engineer to clean refrigerant pipe with liquid or nitrogen gas, from drier flare to suction pipe and flare to charging valve and change expansion valve , flushed properly, charged gas R409a and change filter,it will be back to normal,probely its a day job, if you get any querry info@xpressrefrigeration.co.uk

regards
yusuf

[Peter_1]

I have a lot of experience with these kind of cooling, eutectical plates.
We need more information to help you, especially because we can't put our gauges nor a thermometer on the unit.

What's the compressor type?

What's the type of the expansion valve because it's weird you have R12 for a freezer truck? Eventually use a mirror to read everything on the valve.
How many valves and all th same type (check if a previous tech hasn't installed a wrong valve because it seems you live in a neighborhood with few experienced techs)

How many plates in the van? Also on the walls and roof?

Do you know running pressures?

Is there a crankcase suction limiter installed in the suction line , just before the compressor?

What's the color of moisture indicator the sight glass?

What are the settings of the pressostat?

What is normally switching off the compressor (pressostat or thermostat)?

If the unit ran the whole night, what is then the suction temperatures and pressure?

You had 2 bad techs: the first should repair his own faults,
The second repairs, it doesn't cool and he's checking for leaks. Was there any reason he should do this, was there a shortage of gas?
He then finally changed from r409a to mp66 just as this should change anything because both have +/- the same properties.

You have to reach an evaporating temperature +/- 10 K below the eutectic temperature of the mixture inside the plates.

Try also using SI units between brackets like 32°F(0°C), otherwise difficult to read for us in Europe, same for pressures.

I bet they used the wrong gas

[wunderben]

i suspect oil logged evaporator. very common in low temp static systems.

[Peter_1]

It worked fine since 1999, then compressor must also be without oil in the sump.
So there's changed something since some weeks or months.
This is important.

If oil stays somewhere in the system, then this mostly is due to lack of gas where mass flow in the lines reduces.

On the other hand, we're speaking of a very small system and with few tubes in it (eutectic plates)

[Yusuf Ismail]

hi thats cool

[Yusuf Ismail]

If you need any queries dont hesitate to contact us.

[vtmpnate]

Hi GaryC. It would help if you gave the truck's service history and any regular maintenance work that you do on your own. If you've been using it since 1999, could it be that your condenser is just clogged up with 9 years of dust and lint? That could send up your discharge pressure, forcing a lot oil out of the compressor and into the rest of the system; high discharge pressure and low compressor oil levels may also be setting off pressure switches and interrupting your plate cooldown. While eutectic plate systems are fairly simple, keep in mind that it (and the box it is mounted on) is a system and all components must be in good working order for the system to do its job.