Help for a newbie with a Toshiba Split A/C with no cooling/heating

[MoreThanP]

Hi everyone,

I'm a newbie here both to the forum and compared to most of you guys a complete newbie to refrigeration and A/C but I have been following the various forums for a number of years with great interest. I am now qualified, trained and tooled up but like all things it's all about real world experience and that is where my limitation lies. I am keen to learn and do the job properly so I hope you will help me with the following problem, which for you guys is probably trivial.

I have been undertaking basic servicing of a Toshiba split A/C system which was not installed by me (outdoor unit - RAS-18SAV2-E, Indoor unit RAS-B118UFV-E .. floor mounted) for a two years but this year came to clean filters, coils etc, check air flow and air/air off temps to find that the units were basically just moving air through them with no cooling or heating effect. The air on/air off temperatures at the indoor or outdoor units in either cooling or heating modes (when set to Hi-Power) showed but 0.5 C difference. Both fans were operationally shifting plenty of air through the units (same values as last year) and no externally obvious faults were apparent. On quizzing the customer regarding the performance over the last year, they felt that it had deteriorated but they hadn't actually used in that much as it had been a mild winter (the indoor unit is in a conservatory!), there had really started to notice it with the arrival of the warmer weather and thought themselves that not a lot of cooling was going on.

I have checked the self diagnostics codes via the remote controller and all were clear except check code 12 ('trouble on other indoor PC boards). I cleared the fault code, powered down and up, ran the units for a while and checked to see if the code presented again ... but it didn't.

The refrigerant pipework insulation is in poor condition in parts and we are due to replace it but have held off just in case something serious is amiss.

On connecting my gauges to the service port the static pressure was 7 bar, and running up at Hi power again I got the following pressure readings after 15 mins running:

In cooling mode - 2 bar (the unit cut out after approx. 10 mins with pressure rising to 10 bar, then restarted after a short while and pressure again dropped to 1 bar) the indoor air temp was approx. 22C and outdoor approx. 20C. Cooling set to 17C. After a few minutes thin frost began to appear on the liquid side valve at the outdoor unit.
Heating mode - 16 Bar with set temp of 28C.

The compressor was difficult to get at and I could not access it and have the unit running at the same time, but with the unit off the compressor body and discharge pipe were hot to the touch.

The cooling and heating running pressures seem a little low to me (the service manual suggests 8-10bar in cooling mode and 29-30bar in heating mode (but the operating conditions are different).

My initial thoughts are on the lines of either low refrigerant charge or restriction in refrigerant flow but I'm not entirely sure where to start beyond that.

I hope I haven't rambled on too long and would be grateful for you thoughts and advice as the route to take.

Thanks, MoreThanP

[install monkey]

take the valve caps off to ensure both ports are full opened (allen key), if they are then degas it,weigh it , if different from the factory charge ( additional charge req if over approx 15mtr) pressure test,repair ,vac and regas

[Tayters]

Probably short of charge.

Reclaim, verify charge short, find and sort leak.