Need a help From u all , Problem in ductable unit

[kannanlog]

Hi Everybody,

I need a help from all. Im Facing a problem in DAIKIN Ductable unit.

The unit installed and it is working fine for last 5 months. Now there is a problem in the unit.
In early morning around 3am Everyday ice formation occurs in the indoor coil and there is no cooling effect for more than 3~4 Hours.
After passing 3~4 hours the machine working normal.

Can anyone explain the cause of iceformation in the indoor coil.

[LRAC]

Hi Kannanlog and welcome.

The daikin unit should give out fault codes when this occurance happens, you will need to interigate the remote control to find the display fault.

I have included some codes which you may find useful.

Kind regards
Lrac

[Abby Normal]

Ice would mean low load, or low charge.

A good example of low load is no airflow. A dumb question, but has the air filter been changed in the last 5 months?

[Abby Normal]

Are there motorized dampers in the ductwork?

[kannanlog]

Thks Lrac. But there no such error codes generating in the remote control.
Airfilter also replaced.
If the filter clogged and low gas , iceformation should occur at all the time. But day times the unit working normal, only at early morning 3 am ice formation occurs and cooling effect is bad.
yes the motorised damper in the duct work only.

[LRAC]

What sort of night time ambient temperatures are you getting at the moment, has the outdoor unit got a fan speed controller on it?

Lrac

[Abby Normal]

You made it sound like it thawed out. Could be refreezing. So I assume you checked the air flow and the filter and eliminated the obvious.

A closed fire damper was a common cause of freeeze up as well however you said it was cyclic, so I asked if there were motorized dampers.

[frank]

Ice formation on the coil means that the coil temp is going below 0C whereas it is designed to stay above freezing.

If it happens all the time then the airflow/gas charge should be checked, as has been advised previously. If it works fine during the day but not at night then the problem must lie in the night time temperatures.

I would look at the ambient sensor on the outdoor unit which controls the fan speed. If the fan stays on high speed during low ambients then the liquid temperature may drop below freezing (excessive sub-cooling) causing your problem.

Put the sensor into a very cold wet cloth during the day and look see if the fan speed drops.

[Peter_1]

If the fan stays on high speed during low ambients then the liquid temperature may drop below freezing (excessive sub-cooling) causing your problem.

Is it due to increased SC or more due to the fact that when HP decreases (fan turning on high speed), the volumetric efficiency of the compressor gets a serious boost where you then will see a large LP drop?

[taz24]

Thks Lrac. But there no such error codes generating in the remote control.
Airfilter also replaced.
If the filter clogged and low gas , iceformation should occur at all the time. But day times the unit working normal, only at early morning 3 am ice formation occurs and cooling effect is bad.
yes the motorised damper in the duct work only.

I'd be tempted to look at the out side temp. What temp does it fall to in the night. It could cause problems if the unit is over condensing.

Cheers taz.

[coolflow]

also is it poss to set the indoor temp on the controler to a higher temp like 20c so as to switch the unit off befor it frezzes

[Obi Wan]

Hi Everybody,

I need a help from all. Im Facing a problem in DAIKIN Ductable unit.

The unit installed and it is working fine for last 5 months. Now there is a problem in the unit.
In early morning around 3am Everyday ice formation occurs in the indoor coil and there is no cooling effect for more than 3~4 Hours.
After passing 3~4 hours the machine working normal.

Can anyone explain the cause of iceformation in the indoor coil.

Hello Kannanlog,

Can you tell us what is the model number of the outdoor unit. This will tell us if you have a split, multi or VRV system. Also are there two or more systems installed in the building and are the outdoor units in the same location. If you have a split system and two or more outdoor units installed close to each other, there may be a cross wiring or piping. i.e. the thermostat on indoor unit A switches on but the gas is flowing to indoor unit B (this may be the one that is freezing). Mostly if the indoor unit freezes up it should trip out on freeze protection (indoor coil temp has to be below -1*C for 40 mins or -5*C for 10 mins) there is no fault code displayed but the thermostat is forced to OFF.
If it's a multi then it could be that there is cross wiring between the ports connected. i.e indoor piped to port A is wired to terminals for port B.
The best way to find cross piping / wiring problems is to switch off the entire site and run one indoor unit at a time, check you get cooling, if not then coil temps on the other units. (code 41 on the service mode sensor 02).

Hope it helps, good luck and let us know what you find.

Regards

Obi Wan.

[bldref]

Possible voltage drop at these times, or evap fan hitting off due to overload etc.

[wolf]

peter i don't understand you?????

[Obi Wan]

Kannanlog,

What did you find?
Is the system working now?