Fujitsu R410A indoor unit blowing cold air. Why??

[tasbid]

Hi. I have a Fujitsu R410A. The indoor unit frequently stops heating and the fan continues to run, blowing cool (nonrefrigerated) air. During cold nights it is as likely to blow cool air as often as hot air. What may be the problem. Thanks.

[spimps]

Model number would be good.
Are filters clean? if so could be a sensor. Any codes on display or lights flashing ?

[mikeref]

Hi. I have a Fujitsu R410A. The indoor unit frequently stops heating and the fan continues to run, blowing cool (nonrefrigerated) air. During cold nights it is as likely to blow cool air as often as hot air. What may be the problem. Thanks.

Is the outside air below -5 degrees C?
Is the condenser in a position where it is recycling chilled air?
Is the condenser fins free of debris?

[install monkey]

In heating mode unit will go into defrost mode. Defrost should be under 10 mins. If any longer check the gas charge

[spimps]

I would try checking sensor resistances,normally there is a pre heat of the indoor unit before the fan starts up so it doesnt blow cold air.I'm also fairly sure that the indoor fan wont run whilst outdoor is defrosting for the same reason as above.
Is the outdoor unit running when it's blowing cold indoors.
Sounds like an indooe unit sensor failure (had it on other makes with same symptons ) two or three on indoor unit although in the past same symptons has been a control board failure,hope its the former!

[install monkey]

in defrost mode the indoor fan will go to low speed, ive had a 410a unit fail on faulty indoor pcb, in heating mode the unit would run for 10 minutes ok then the relay on the indoor board would drop out causing the unit to run in heating mode but the reversing valve de energised causing constant cooling and as a result freezing up as setpoint is higher than return air temp

[spimps]

OK I see,I'm not that well versed on fujitsu,those I have done haven't been any problem,re reading the origional post it obviously does heat OK for periods and then stops so would rule out sensors as that would always be a fault at start up ,probably needs an engineer armed with a manual,summer cant be far away in that neck of the woods!

[install monkey]

http://www.mediafire.com/view/?5y97lqsrpnsedb4
page 9 gives fault led's-if its a wall mount- are your filters clean?-

[tasbid]

The indoor unit is model ABT24LBAJ and the outdoor unit is a model AOT24LMADL. I had suspected debris blocking the condensor, and cleaned it to no avail. All filters are clean. There are no fault codes or flashing lights. The ambient temperature outside is quite cool, but unlikely to be below -5 degrees. The outdoor unit is running when the indoor unit is blowing cold air. The indoor fan seems to remain on low speed constantly, irrespective of the fan speed selected. It's a floor mount. Thanks for all your help.

[tasbid]

Any more help please?

[spimps]

IMO you need a service manual and meter/meggar to check out sensors etc,possibly pcb but without checking everything else is OK it's a guessing game,maybe contact Fujitsu technical in au.

[tasbid]

Thanks. Has anyone got a service manual?

[spimps]

www.fgeurofred.co.uk