Kingspan Aeromax not producing heat and ice cold rads

[Donkeydarts]

I’m new to this forum and any help would be most appreciated.

I’ve got a 8 year old Kingspan Aeromax ASHP which provides hot water and central heating via radiators with no underfloor heating.

The system has stopped producing hot water/central heating. Initially I thought it might be an air lock or blockage as the unit starts up fine, the central heating pump kicks in but no heat coming from the rads. I bled the radiators and cleaned out the large brass in-line filter near the pump but still with no joy.

The really strange thing is that instead of the rads heating they get ice cold, so much so that condensation appears on them and the pipes.

It seems as if the system is working in reverse by cooling and not heating?!!

An error message did appear once on the panel which was code 15 which is exit water thermistor out of range but it only did it once but assume this is due to the cold water temperature?

Any ideas what the issue is before I have to shell out of a new unit.

Thanks

Edited October 8, 2021 by Donkeydarts

[SteamyTea]

Has it been set to cooling mode somehow.

 

Your unit may be a rebranded Carrier ASHP.

 

Some people pay extra to use cooling mode.

[Donkeydarts]

Well nobody has touched the system and it’s been fine so can’t see why it would all of a sudden start doing it unless there’s a technical issue?

[SteamyTea]

Can't help then.

[Donkeydarts]

Bit of an update. I noticed that when the fans kick in on the ASHP unit they are blowing hot air not the usual ice cold air!  Seems that everything has started going arse about face for no apparent reason.
Any suggestions welcome ? 

[PeterW]

4 way valve is stuck in defrost position. A slight tap with a hammer sometimes releases a stuck solenoid. 

[Donkeydarts]

Sorry to be a pain but where is the 4 way valve? Thanks

is this it?

Edited October 8, 2021 by Donkeydarts

[Donkeydarts]

3 hours ago, PeterW said:

4 way valve is stuck in defrost position. A slight tap with a hammer sometimes releases a stuck solenoid. 

I changed the solenoid as I had a spare unit for parts and it fixed the issue. PeterW I could kiss you!!!!