Air conditioning heating but not cooling help needed

[danielc4514]

So today I had an Fujitsu unit going into heating fine, but when I asked for cooling, it would come on for 20 seconds down to 9 deg Celsius then start blowing ambient air. Fan would ramp right down and turn off.

I tested the pressures and in heating I'm getting 30bar and 35 bar, in cooling I'm getting 7 and 10 bar, tested the reversing valve and that's fine.
Filters and coils clean.

Any ideas would be great.

It's a 15kw running two cassettes, so I have dismissed it being anything yo do with indoor sensors.

Room temp was in the 20's

[Brian_UK]

Pull the charge and check the weight.

Cooling pressures are low so the 4 way valve may not be changing over properly.

Mind you, those pressures don't mean anything because we don't know what the refrigerant is.

[danielc4514]

Thanks for your response. I have tested the 4 way valve and that's working as it should.
Sorry, the refrigerant is r410a..... I'm getting in the 50's when in heating, it's only cooling im having a problem.... so I guessed the refrigerant charge is ok if it's working in heating, or am I wrong?
I dont do a huge amount of fault finding but am trying to get better at it.

[TrickyRikki]

Thanks for your response. I have tested the 4 way valve and that's working as it should.
Sorry, the refrigerant is r410a..... I'm getting in the 50's when in heating, it's only cooling im having a problem.... so I guessed the refrigerant charge is ok if it's working in heating, or am I wrong?
I dont do a huge amount of fault finding but am trying to get better at it.

Have you got the unit details? both indoor and outdoor i may have some bits i can ping over to you

[frank]

How have you dismissed the sensors as not faulty?
Did you measure the resistances?

[scoobyru]

it points at faulty sensor on indoor unit to me too if cutting off so quick , best to unplug it and check its resistance.