Is The Water Pump Set To Flat Out? - Samsung RC090MHXEA Service Manual

Test 2 if the unit passes test one you now need to start the unit up, when it starts up watch
the outdoor unit, if it starts up and operates for about a minute and then trips on E407 the unit
is running against a refrigeration blockage, its highly likely that the expansion valve is not
opening quickly enough. This is caused by a pcb failure, the valve being stuck or a sensor
failure.
The first thing to check is the refrigeration expansion valve; it's like an electric version of a
TRV. It's located inside the unit half way up on the right-hand side.
DO NOT TURN OFF THE
POWER, loosen the expansion
valve head using two spanners, no
fgas will come out, turn the top of
the valve 1/2 turn anti clockwise,
note it has marks on the nuts.
DON'T reset the power. Now start
the unit up does it now work? If so
the valve was stuck. It's a very
good idea to replace the outdoor
unit pcb.
When the new PCB is to be installed, with the unit operating kill the power, gently tighten the
valve head, don't over tighten it, use had tightness only. Now kill the power and replace the
PCB with the new one, restart the unit.
Test 3 If the unit starts up the compressor and then fails on E407 after more than 5 minutes'
operation of the compressor, it's because the unit is not getting rid of the heat. This is
because the water is not flowing through the unit fast enough.

is the water pump set to flat out?

Check the ball valve on the filter ball is fully open, this will reduce flow if its shut, use a flat
screwdriver or a spanner to move this.
What is the hot water set temperature?
Does the unit trip on 407 in heating or hot water mode? If hot water mode, can you double
check the tank sensor is fully in its pocket, check its not been pulled out, if you pull it out 2 cm
the unit wont record the tank temperature properly and it will overheat hence E407. Check the
tank thermistor isn't lower than the immersion, the hot water returning from the tank will cause
this trip.
If its tripping in heating mode is the heating pump z1 operating? It should be wired into 22 live
and 19 neutral with the heating run signal.
www.freedomhp.co.uk
Turn off the power to the outdoor unit,
leave it off for 2 mins, turn it on and hold
on to the expansion valve, in the first two
minutes you should be able to feel it
moving inside, it fizzes as it turns. If it
does not do this the pcb or the valve
head is faulty, its best to replace both.
If it does fizz the pcb and motor are ok.
We need to check the valve body is not
stuck.
©G Hendra Nov 18 27