City Multi heating issues

[carrola7]

I'm working on a city multi PURY-P300YGM-A. Its cooling fine but not heating at all.

When I began work on the unit I noticed a few things. Firstly the unit seemed to be grossly overcharged. Additional charge labelled was 28kg. Recovered gas, replaced high pressure ball valve (which was partially seized) and re-charged with 14kg additional charge.

I also relplaced the HP sensor, which was reading way out of calibration.

The site is one we have just inherited. It looks like this particular unit has some history as the four way valve looks like it has been previously replaced.

I haven't checked the BC box LEVs yet. That's one for the morning. In the mean time can any of you throw an eye over the attached service checker readings and see if I'm missing something obvious?

[carrola7]

Sorry, forgot to add a heating thumbnail...

[RusBuka]

4 way valve dead by arrive)))
As i see discharge don't go to BC units. Outdoor unit work with bypass from dis -> suc

[carrola7]

Okay so I swapped LEV1 and LEV3 and the system is running fine in both heating and cooling modes. Not quite sure what to make of that.

[marc5180]

In cooling only mode LEV1 should be fully open (2000 pulses) to maintain 0 - 14.7 psi across the sub cooler circuit.
In the 1st photo you sent, LEV1 shows that it is indeed 2000 pulses open but it isn't doing what it should. This can be seen by the dPHM reading which is 52.6psi and so LEV1 is faulty.
This will be causing flow issues around the system.

[carrola7]

Could a faulty LEV1 explain the poor heating performance? Also could faulty pressure sensors P1 or P3 also explain the high dphm reading?

[marc5180]

Yes faulty pressure sensors would give an in accurate Dphm reading
In heating mode/heating main LEV1 is used to maintain 3-4 bar diff to increase the flow around the system.
If P1 and/or P3 were out of calibration, the LEVs will still open and close to try and maintain the above figures which will affect flow around the system.

[marc5180]

The best thing to do, would be to switch off all of the indoors on the g50/ag150 and leave them off for ten mins and then check that all the sensors and the pressure transducers read the same figures.

Only last week I had Th2 in the BC box consistently reading 30degc above the actual figure.
This was causing LEV3 to open more to try and bring down SH12 (across the subcooler circuit) because it thought the superheat was to high.
This was found by the above procedure and was relatively straightforward.