Panasonic icing up

[Jadeair]

I put a split into a butcher shop ( Panasonic cscue24gkr 7.4kw). The shop front is 5m X 5m and has a few self contained units in it. The front door is keept close and has strip curtains.

The unit seems to run fine for a while then ices up ever now and then.

I have caught the owner dropping the temp down to 16 C in the past. Which he tells me he leaves it at 21 c now.

The unit is set on its remote timer to be off for 6 hours a night.

The evaporator coil td is around 16k, not bad.

I might reclaim the gas tommorow and weigh it back in to make sure it's right. I've put lots of these in and never had a problem.

Almost sounds like the evap fan stops now and then. Havn't had too many splits ice up even if the filters are blocked up.

[Lastguest]

I put a split into a butcher shop ( Panasonic cscue24gkr 7.4kw). The shop front is 5m X 5m and has a few self contained units in it. The front door is keept close and has strip curtains.

The unit seems to run fine for a while then ices up ever now and then.

I have caught the owner dropping the temp down to 16 C in the past. Which he tells me he leaves it at 21 c now.

The unit is set on its remote timer to be off for 6 hours a night.

The evaporator coil td is around 16k, not bad.

I might reclaim the gas tommorow and weigh it back in to make sure it's right. I've put lots of these in and never had a problem.

Almost sounds like the evap fan stops now and then. Havn't had too many splits ice up even if the filters are blocked up.

It is fairly common on small splits where there is poor latent heat transfer so the refrigerant doesnt boil off in the coil. Because of this it seems the refrigerant cools such that the surrounding air rapidly cools then freezes on the coil. Try to get as much air flow over the heat source and back as possible. Lock the thermostat if you can. Set the thermostat up to 22/23C Size the equipment accurately.

Hope it helps. then again maybe it IS the fan

Last

The moving finger writes and leaves a broken fingernail behind

[stefs_cruiser]

Has the owner ever seen the TIMER light flash?

If a fault code is detected the unit will flash the timer light, you can still check the error afterwards by holding down the CHECK button on the remote for 5 seconds (the controller will go blank) and then sroll trough the fault codes with the TIMER up button, intil it beeps several times.

if it is H00 all is normal.
if it is H19, it mayhave a fan problem.
if it is H99 than it has iced up due to lack of refrigerant etc.

Also, are you sure the unit switched off at night?
some early CS-E24GKR's had a bug in the remote, in regards to the timer functions.

But most of all, tell the customer to run it on 22 as suggested, otherwise at 16 and hosing the place out like they (butchers) do, it will ice up again.

[back2space]

Have you tried running the fan in "HIGH" speed and seeing if he has the same problems?

[Thermatech]

Gday mate
Standard split systems are designed for comfort cooling & about 50% humidity.
The indoor coil is designed for this air humidity which means there is some latent heat load & sensible heat load.

For your application the self contained refrigeration display cases make lots of sensible heat but no latent heat. So the air in the room gets really dry as the a/c units constantly dehumidify the air in the room. With door curtain or shut doors the RH in the room can easily drop low enough for coil frost condition at the indoor coil.
If there is no fresh air coming into the shop then you will find the humidity level will drop really low.

Can the fresh air be very dry & low RH also ?

If the air on coil humidity RH drops lower than 40% then you are into coil frost prevention conditions.
If the indoor unit has no coil frost prevention function or its not working correctly then the indoor coil can frost up.

1/ Max air flow through the indoor coil will help.
2/ HP contol set up to increase discharge pressure high enough to ceep evaporating temp at indoor unit higher than coil frost prevention conditions can be depoyed but will reduce efficency & increase amps a bit.
3/ Make your own coil frost prevention control to stop the compressor for a few mins when the coil starts to frost to allow the indoor coil to warm up with fan still running. Thermostat & time delay relay with interconnect wiring between indoor & outdoor should do the trick.

[Jadeair]

Checked the unit over the last couple of days and its been going fine.

Checked fault codes on the remote and it beeped on H00 so all was good there.

Reclaimed the gas and there was 1420 grams. Regassed with 1650 grams as per specs. Pressurised with nitro prior and leak checked, all ok.

Will have to speak to panasonic about the remote bug. I put the remote upto 25c and the unit didn't cut out for about 5 min till I put it upto 26c, so the thermistors might be out a bit.

You can get a monitor for Daikens that hook in and show a read out of thermistors, don't know if Panasonic have the same thing?

The system runs fine for weeks then suddenly ices up, must be a bug in there somewhere. You would think if the self contained units where causing the problem that it would happen all the time.

Thanks Guys for your help I'll keep you posted.

[stefs_cruiser]

A Panasonic inverter has quite some criteria before it will cycle off.
They have a minimum run time, and will go 1 degree past the set point etc etc

Thermistors are best checked with a ohm meter, and the service manuals have the resistance v's Temp graphs.
but at 25 degrees C they are 15K ohm. they also have a negative temp coefficient.