true freezer problems

[4rjn]

I cannot figure out what is the problem with this unit. I have replaced the drier and pressure valve. I have vacuumed the system multiple times. I put manufacture recommended r404a by weight in unit. It runs high side is hot cold side is just cool not cold. gauges are reading good values at outside adjusted temp. Freezer is not cooling at all temp around 75 inside after running for long period. please any thoughts would be appreciated.

[icecube51]

first tell us what is "hot" and what is "cold" in C° or F . did you do presure readings on low and high side ?? is the condenser and evaporator clean and free of dust ??? are the fans running and the air displacement is ok ?? is the air passage ok on the condenser and evaporator?? how is the temperature before and aft the condener / evaporator??
give us some more info so we can help you better.

Ice

[4rjn]

Pressure 180 high 110 low, everything is very clean, fans are both running good and air movement seems very good. I do not have a infra red thermometer so I cannot measure exact temps. I hope this helps

[Yuri B.]

Considering pressures, comp is not pumping good.
What had been initially with the freezer ? (prior to the replacements)
What do you call "pressure valve"?

[andywill]

On the low side you should be looking for a pressure between 15 and 12 psi for R404a on a frozen food application.
Sounds to me like you have a compressor pumping problem!!! Have you done a pump test on the compressor?

[4rjn]

the valve is a sporlan cro-6 crankcase pressure regulating valve. The freezer was only getting down to about 5 degrees and the ice cream was border line soft. Maker of ice cream says it needs to be -10 which true manufacturing says this unit is capable of it. I added about 6 oz. of liquid of 404a as the system was low. The high side gauge started to jump a lot so I figured it needed a new drier also at that time found a little bit of oil near the crankcase valve so I replaced that while the system was apart. vacuumed for 1.5 hours recharged to man. weight that is when it would not get cold at all. so I added about 10 oz more to system but did not get any change i cooling. That is where I am. thanks

[4rjn]

is it possible to do a pump check while it is still hooked up? If so can you explain it? thanks

[Gary]

Which side of the CPR valve are you taking your low pressure reading at?

[4rjn]

I am reading after the valve at the port to the compressor

[Gary]

What was the pressure before you replaced the CPR valve?

[4rjn]

gauge is bouncing badly on high side, low side now at 70 and high at 180 after replacing cap tube and clean out with nitrogen then 1.5 hour vacuum stopped and then .5 hour vacuum.

[Gary]

gauge is bouncing badly on high side, low side now at 70 and high at 180 after replacing cap tube and clean out with nitrogen then 1.5 hour vacuum stopped and then .5 hour vacuum.

Did you adjust the CPR?

[4rjn]

I am pretty sure the pressure was around 70 before I replaced the cpr but I did not write it down and I have gone through this to many times so I am starting to forget where I was. Should have wrote it all done, dumb mistake!

[Gary]

The purpose of the CPR is to prevent compressor overloading on pulldown. Did you adjust it?

[4rjn]

pressure before the valve is 170. I tried adjusting the valve and putting the gauge back on the port after the valve and I do not get any change in low side pressure by turning the adjuster 5 turns in and then back to start then 5 turns out with no noticeable difference in low side reading.

[Gary]

That's because the valves are broken in the compressor.

[Gary]

the valve is a sporlan cro-6 crankcase pressure regulating valve. The freezer was only getting down to about 5 degrees and the ice cream was border line soft. Maker of ice cream says it needs to be -10 which true manufacturing says this unit is capable of it. I added about 6 oz. of liquid of 404a as the system was low.

What made you think it was low?

[4rjn]

when we first got the unit a year ago there it was very low on refrig. we put acr super seal as we could not locate the small leak it appeared to be in the lines inside the cabinet and not acessable. we sniffed and soaped everything with no luck. It had been doing fine for 11 months so we thought it was good to go then this all started. I put the gauges on and it appeared a little low so that is when I topped it off and everything went haywire.

[Gary]

Yeah but... what made you think it was low?

"I put the gauges on and it appeared a little low..." doesn't tell me how you came up with that diagnosis.

[4rjn]

The high side was at 65 degrees on the 404a scale and outside temp was around 76 degrees that factored with the lack of cooling and a history of a slow leak lead me to think it was low on 404a.

[Gary]

Hmmm... In order for the saturation temp to drop below ambient there would have to be only vapor in the system. The system would be almost empty.

Did you evacuate the system and charge according to nameplate?

[icecube51]

somewhere along the circuit there is a valve ho is liquid chocking the suiction side of the comp. hopefully the comp hasnd got liquid flod on the suction side or the valve are brocken and the comp needs to be replaced.

Ice

[andywill]

If you want to pump test the compressor then you should fit your gauge to the suction service valve of the compressor, whilst running you shut the valve all the way in and you should see the suction gauge fall to the cut out pressure of the low pressure switch (if fitted), otherwise it should pull a vacuum. You then shut off the compressor and it should hold that pressure providing that there is nothing else injecting into the comp such as an oil return line or liquid injection valve. These can be isolated for the test if they have service valves fitted.
Same for the high side only if it has a High pressure switch fitted, it should easily reach the cutout pressure.

[4rjn]

Thanks andy and ice, gary I have vacuumed the system multiple times with the shortest period being 1 hour up to 2 hours and then charged according to weight on man. plate every time. We have taken the head off figuring there must be a valve problem and found one reed was shifting and leaking by because it was not seating properly anymore. Hopefully this will fix the problem. Parts are ordered.

[4rjn]

Ok took the head off and found the suction reed was bad and it looks like it took out the gasket. I replaced entire valve head and both reeds, changed comp. oil another new drier since everything was apart, new sporlan liquid sight added to see what is going on. Vacuumed for 1.5 hours with fresh vac oil too. Charged to plate on cabinet by weight then topped to clear on sight glass. The gauges are at 180 psi high side and 5 psi low side. The cabinet after running for 2 hours is only at +20 degrees f. What am I missing??

[Gary]

Open up the CPR until the pressure at the compressor inlet is about 70 psi. If it won't go that high, then you may need to shut down the system and warm it back up. The best time to adjust a CPR is with the freezer at room temperature. If set too high it will allow the compressor to overload. If set too low it will underload the compressor and the pulldown will take forever.

[benji]

Hows your txv setup? whats you superheat like? is the system fully charged?

[benji]

if your pressure is equalizing on low side and high side then you valves are shot.

[4rjn]

I set valve at full pressure and I can only get 7 psi on the low side. I tried the valve the other way just to be sure I was not turning the wrong way and it went into vacuum below zero. I am thinking there must still be an obstruction somewhere in the cap tubes? What do you think??

[4rjn]

Oops forgot to mention which makes me wonder when I had the drier out I put the vacuum on just to see and I did get vacuum from both lines the one heading to cap tubes and the one back to the compressor. Of course I had no way to measure how much of a pull there was which makes me wonder if there really is an obstruction. There are 2 cap tubes could it be on is plugged and the other ok?

[Gary]

Did you shut off the freezer and let it warm up to room temperature?

[4rjn]

the valve is only rated 0-60 psi I do not think it will allow higher then that????

[Gary]

60psi should work just fine, but if the compressor kicks out on its overload, set it lower. You want it high for quick pulldown, but not high enough to overload the compressor.

[4rjn]

Found kink in 1/2" return line, thought maybe that was it. Nope replaced the whole section, vacuum, charge, same problem. 0 psi on the low side so I hooked the gauge to port before pressure valve and it still is 0 psi. So I do not know what else to check. Anybody have thoughts about maybe the cap tubes being partially blocked. There is not much else to check and replace on this unit. Thanks

[4rjn]

sorry Gary I just so your other reply I did not mean to say that the gauge was showing that, I wish, that is just the rating on the valve. I just posted current readings with pressure valve set at 60 psi. obviously it does not matter where I set it if the pressure before it is at 0 psi. thoughts ???

[Gary]

Is the freezer off? At room temp?

[Gary]

I just posted current readings with pressure valve set at 60 psi. obviously it does not matter where I set it if the pressure before it is at 0 psi.

Exactly. The CPR only comes into play when the freezer is warm. Once the evaporator pressure drops below the CPR setting it is as if it wasn't there. It provides an upper limit on cranckcase pressure.

[4rjn]

yes the freezer was off and at room temperature. Shouldn't there be pressure before the valve once it is up and running for a while? Thanks

[Gary]

yes the freezer was off and at room temperature. Shouldn't there be pressure before the valve once it is up and running for a while? Thanks

Is that zero psi with it off?... or zero psi with it up and running for a while? Which is it?

[Gary]

new sporlan liquid sight added to see what is going on. Vacuumed for 1.5 hours with fresh vac oil too. Charged to plate on cabinet by weight then topped to clear on sight glass.

There is a reason manufacturers don't put sight glasses on cap tube systems: They don't want you to come along and top up the charge to clear the sight glass. It is supposed to have the charge it says on the label and no more.

[4rjn]

Yes it is zero after it is running for about 45 seconds.

[Gary]

When you shut it off do the pressures equalize?

[kalapala]

Hi All,

· I just got knew this site. I have problem with my Hotpoint fridge & Freezer(FFA74 model)
· This is 3 years old and water leaking from fridge from couple of weeks then cleaned the value on the fridge still water leaking ,recently OK button inside fridge gone off and again after 3days and seems ok.
· From 2 days Freezer high temp light was on top of unit and all food in freezer stared defrosting and I did put fast freeze button on but that doesn’t seems to work.
· Any advice please I have got little girl I need store food in Freezer, tried moving unit ,cleared all the back but doesn’t seems to work…
We tried doing some checks last night please help me ..I am going mad with this problem.

[4rjn]

Yes pressure does equalize when off. I talked with true the other day and they suggested a new complete line set with the new cap tubes so I ordered them and they should be here next week. I will install and pray it works.