Foster freezer not cooling

[SchoolBoy]

Hi all. I have a problem with a small foster freezer, the issue is that it is not cooling at all, but keeping the temperatur inside at a constant 20C (compressor is running).

Refrigerant used is R404, I presume that there is not enough refrigerant in the system.

These are the symptoms:

1. Compressor is running and is warm.
2. Output line from compressor is warm/hot and goes into condenser
3. Output line from condenser is cold (condenser is watercooled)
4. I presume there is no TXV in this freezer, but might be wrong if I say that the pipe connection into the evaporator is used as a TXV? smaller pipe goes into the evap coil, where the pipes are larger.
5. Pipe which goes into the evaporator has slight freeze on it, but the evaporator is warm. Evaporator is clean and not iced up.
6. Suction pipe to compressor is warm.

I have made a slight diagram on my system. Can anyone of you please also advise from where should I start if I wish to refill the system? I have got all of the required equipment (refrigerant, gauges, hoses, even refrigerant scales)

There are 2 topping up points (with connections allready), one is going directly into the compressor, and the second one is on the output side of the compressor.

http://www.upload.ee/image/1499398/foster_fridge.jpg

Also can you please advice, why is the input line to the evaporator coiled around the output line of the evaporator?

[cool runings]

Hi all. I have a problem with a small foster freezer, the issue is that it is not cooling at all, but keeping the temperatur inside at a constant 20C (compressor is running).

Refrigerant used is R404, I presume that there is not enough refrigerant in the system.

These are the symptoms:

1. Compressor is running and is warm.
2. Output line from compressor is warm/hot and goes into condenser
3. Output line from condenser is cold (condenser is watercooled)
4. I presume there is no TXV in this freezer, but might be wrong if I say that the pipe connection into the evaporator is used as a TXV? smaller pipe goes into the evap coil, where the pipes are larger.
5. Pipe which goes into the evaporator has slight freeze on it, but the evaporator is warm. Evaporator is clean and not iced up.
6. Suction pipe to compressor is warm.

I have made a slight diagram on my system. Can anyone of you please also advise from where should I start if I wish to refill the system? I have got all of the required equipment (refrigerant, gauges, hoses, even refrigerant scales)

There are 2 topping up points (with connections allready), one is going directly into the compressor, and the second one is on the output side of the compressor.



Also can you please advice, why is the input line to the evaporator coiled around the output line of the evaporator?


The expansion valve on this system is not a valve but a cappilary tube that is
about 2 mtrs long. The cappilary tube restricts flow of liquid causeing the
pressure drop after it, which then creats the cooling effect inside the evap.

The pipe is wrapped around the outlet (suction pipe) for two reasons.

One is the cappilary is fragile so needs protecting.
the second reason is the most important. The cappilary is carrying warm liquid
to start with, but that liquid needs cooling before it enters the evap. Wrap the
cappilary around the suction and the heat is transfered from the colder suction
pipe the smaller cappilary. This also transfers heat to the larger pipe and that ensures
all the liquid is boiled off before the refrigerant returns to the comp.

As for the fault don't just assume the thing is short of gas. Other faults can look
similar and unless you have the right equipment and experience you could do more
harm than good.

coolrunnings

.

[install monkey]

pot f****d- warm discharge,warm suction,or short of gas.

[SchoolBoy]

Should the pipe which is going directly into the compressor with a cap be the suction side?

I could connect the gauges to the suction and discharge and monitor the pressures first, right? Suction should be something around, or above 0bar, but how much should the discharge be?

[monkey spanners]

I'd be thinking more like a blocked drier if theres frost on the capilary tube.

Does it have a data plate with the factory charge on? You need to weigh out the refrigerant with a recovery machine and bottle to see if its got the correct charge.

Also if you're in the EU as you'll need to have passes a reconised F-Gas assesment to be working on the gas side of these systems.

The pressures in the system change with the temperature so there isn't a correct temp to charge to.

[texas64]

Replace the cap tube and filter drier. Problem should be solved. In R404a and R134a systems, I have found that cap tubes tend to restrict, especially the R404a systems. Not sure whether or not it's a break down of the synthetic oils used (POE, alkybenzene), but this is common. Unfortunately, this problem may return. If your customer will pay you, I would recommend installing an internally equalized TEV instead of the cap tube. Sporlan SQ bodies are awesome for this. I have had wonderful success with this. Install a sightglass too. I pipe in 3/16" (not sure how copper is measured elsewhere. I am in the USA) copper tubing because it's very flexible from the filter to the TEV. I have even installed the TEV outside the cabinet due to space restrictions, piping in through the wall of the cabinet making sure the line is insulated to the evaporator coil. Its kinda funny to see an expansion valve near the condenser! You may install a hard start kit to ensure starting, but I have not installed hard start kits as well with the same success, as many fractional compressors already have a start capacitor anyway. Just look at it this way, if you have to return for another restricted cap tube, now you have worked twice as hard and even giving some work away as warranty. Call backs are no fun for your ego!

[cool runings]

.

Don't just jump in condeming and changing things.

You need to find the fault and from your description and explanation
there could be many, many faults. You do not have the knowledge to
correctly cary out this repair otherwise you would not ask.

I know that sounds harsh to you, but do you have the correct qualifications
to work with refrigerants? I doubt it.

coolrunnings

.

[r.bartlett]

Now we have F-Gas and still people can't help themselves offering advice. I often wonder if it's for the good of the poster or to 'show off' to the regulars.

Never in a million years would I offer advice to someone with this level of knowledge without first assertaining their status within the industry. By offering advice to unknown users is self defeating and unprofessional.

[install monkey]

ill talk to anyone who spends that much time on paint shop to draw a diagram like that. im going to put a disclaimer on my comments- if ur daft enough to f**k about with a pressurised system without relevent qualifications and you blow urself up or cause extreme damage to equipment-then nowt to do with me.
should web ram req occupation when posting

[SchoolBoy]

Thank you for your advices and comments guys.

First of all, I'm not a guy off the street asking for help. I got some on layer knowledge about refrigeration and AC systems. But not completely familiar with everything. I am not offering this as a service but doing this for myself as private.

Will look at the pressures first before I start refilling or anything. If there will be vacuum on the suction side I will think from there further (and ask for help :D)

[SchoolBoy]

Fridge has been refilled and works like a charm. Thank you for the ones who advised.

[install monkey]

well done-good to see an updated post with a happy ending-hope u havent overcharged it haha