View Full Version : cooling problem and intermittent fan

31-03-2015, 04:50 PM
Hi ,

I have a problem with my single split heat pump system. its a 5kw Fujitsu unit.

I havent used it in a while but turned on today and put down to 18 degrees but it doesnt seem to be cooling properly (doesnt seem very cold) and even with fan set to high it cuts out every now and then .
But it doesnt throw up any error codes .

Ive checked filters and out door unit are spotless .

using r410a gas

Any ideas ??

Many thanks for any help im still in first year of my fgas training so nice to get bit of knowledge too

The Viking
01-04-2015, 12:17 AM
Any flashing lights/LEDs or fault codes?


monkey spanners
01-04-2015, 10:25 AM
Sometimes you get a fault code on the outdoor board leds when nothing shown indoor. Sounds a bit short of refrigerant to me, but am bit out of practice with ac.

01-04-2015, 02:32 PM
Hi thanks for replys ,

Not showing any fault codes/flashing leds on indoor unit will try to take a look at outdoor see if its flashing anything up.

Its a real strange one as it starts to cool but then stops . everything is fine on heating just get the problem on cooling . checked simple things like liquid line frosting and such but is fine .

one strange thing i did notice was outside unit was blowing warm air as expected on cooling but then stopped and when it restarted it was blowing cool air , really not sure what this could mean ?

Little update : After running on heating for 5 mins then switching back to cooling everything is now fine , cooling is working nicely for over an hr could it be a sticky expansion valve problem ??

01-04-2015, 08:02 PM
Job for those kids in the Mystery Machine, probably the janitor ha ha.

Alright, I wont give up the day job just yet.

Would need to know suction pressure to confirm if EEV suspect but some older Fujitsu's had problems with EEV coils breaking down. Heating would work fine but cooling would just have the unit pumping down, no codes at first, possibly discharge thermistor or some inverter code might crop up eventually.
To test check resistance between red+orange, red+white, brown+yellow, brown+blue, 40ohms each.

Would help to know room probe resistance, perhaps reading too low?


01-04-2015, 10:10 PM
Sounds like lack of pressure to change over the reversing valve.

A bit of oil logging perhaps having been off for a while???