A strange problem

[MuhengineeR]

Actually I am not an expert of refrigeration, but a new mechanical engineer of a company working on air conditioners,
we have a problem in a mono split type air conditioner, which is old( I dont know how much old), it is being used just for cooling in a measurement department of a factory. its problem:
in summer, it has no problem but in winter, when it is powered on, in 30 sec gives "low pressure error". If it doesn't give an error, it works normally. An inverter kit had been installed to solve the problem but it hasn't... Even if condenser fan doesn t rotate, the error occurs, I think there is too much condensation. Some people think here that we should heat the lliquid tank or change the expansion valve, but it seems to be working normally.. waitng for your suggestions.. thx..

[The Viking]

Within 30 sec.?
First, it would at least need a crankcase heater.
Secondly, it would not have had time to reach a stable running condition after only half a minute - you could fit a timer that "shortens out" the LP switch for the first 3-5 minutes of the compressor starting.
BUT.......
A fridge guy (or A/C engineer) should put his gauges on it and then be able to tell you exactly what happens and what has to be done.

[adams?]

i agree with viking, get some gauges on. possibly also check lp controls - could also be faulty

[chillin out]

Could be a sticky 4 way valve.

Needs a tech to put some guages on it though.

Chillin

[ART KUHN]

could this be it??

In the winter the temperature drops below zero and the pressure drops with it.When the comp starts it's dischards pressure cannot rise fast enough to get a desent suction pressure.

Just a guess

Kind regards Art

[PoodleHeadMikey]

Assuming all to be well with the system; proper charge and so forth, I would install a time delay low pressure control.

It may well be that the system has an LP with a time delay but the time delay function of the control has failed.

Or possibly the time delay low pressure control was replaced with a standard LP control by the unknowing.

PHM
---------

[Shamel]

30secs, not enough time for pressure to balance in the system Maybe L.p switch cut out too high. Put some gauges on, override l.p switch & wait & see what happens on your gauges. if your pressure is correct it could be that your l.p switch is faulty or the electronics on the board which give the errors. also you could try & move the condensor to a warmer location like an enclosed area if your temps are too low but make provisions for heat in summer.

[paul_h]

How cold is it when you get this problem?
You say it's old, but then mention an inverter. Is it 8 years old, or way older?
Is it just a regular type split, or a custom unit? make/model?
30 sec is way too quick to fall over.
It's definitely a tough call to make, could be a faulty r/v valve, or pressure control, or it may need modifications depending on ambient, type and design of unit.
If you can't get make/model, ambients, refrigerant pressures and temps, r/v operation verified etc then you need an a/c tech to check

[casstrig]

Someone has to put gauges on it to see if the press is really low enough to give a lp trip.this may be stating the obvious but you are still using this unit in cooling mode what is your ambient temp type of throttling control and unit model before you provide full information any answers can only be speculation.

[Brian_UK]

Could be that as the OP was in February last year and he hasn't replied that the problem is resolved, or he's given up

[multisync]

Could be a sticky 4 way valve.

Needs a tech to put some guages on it though.

Chillin

Can a sticky 4wv cause a low pressure fault?

Multisync
London

[nike123]

Could be that as the OP was in February last year and he hasn't replied that the problem is resolved, or he's given up

Could be, but we are stubborn as mules and have ego as mountains, and need to express our solutions no matter how late it is!

[Brian_UK]

Could be, but we are stubborn as mules and have ego as mountains, and need to express our solutions no matter how late it is!

I just wish sometimes, just sometimes, that we would get some feedback from the first poster

It doesn't cost much to be polite

[Noori]

I agree with viking,and the system should has the correct refrigerant quantity.
best regard

[Csquared]

Not on an AC.