Any ac guys around

[fatjay]

I have an innovair 24k btu inverter minisplit. I installed it 10 years ago before minisplits gained much popularity. So there's not a lot of documentation or service information available on this particular unit.

Now, it's not getting cold, only cool. I don't have net good measurements, only the measurements I have taken when it's acting up.

Inside unit is showing ~60f at the coil. My other ac unit at the other end of hte house is showing ~35f. The problem unit typically is able to cool the house in about 15 minutes, extremely well.

It is a r410a system. I have a 2lb bottle of 410. I think the issue is the system is low on 410, everything else seems like it's operating as expected.

If it's low, what stage do I add it? And what are my target numbers?

If it's something else, what might it be?

It starts at 120psi.

When the compressor kicks on, it drops to ~40-50psi.

When the compressor kicks off it jumps to ~220psi.

Then it equalizes from there to ~120psi.

 

[workinonit]

My 410 unit that I just replaced ran about 110 PSI on the suction side when adequately charged, in the 80s outside and at or close to room temp. The rest of those observations are irrelevant. The discharge pressure would be worth looking at as well.

 

[Grendahl]

An evaporator temperature around 40 degF is ideal for air conditioning. For R-410a, that would be a suction pressure of 118 PSIG. If the evaporator pressure is lower than 100 PSIG, which corresponds to 32 degF, you risk the condensation freezing on the coil and blocking the air flow. On the high-pressure side, lower is better. The condenser pressure will depend on what your outdoor ambient temperature is. If it is 90 degF outdoors, a condensing temperature around 100 degF would be good. That would be a high side pressure of about 317 PSIG for R-410A. If your condensing temperature is too far above outdoor ambient temperature, it could be caused by insufficient air flow on the condenser, or too much refrigerant in the system, or non-condensables like air in the system.

 

[LouNY]

I would say it is low on charge;

 

[ponytug]

@Sigarms would probably know, but yes, it seems low.

Being low always raises the question to me of where did it go, and how did it get out? Refilling a leaky bucket never seems like a good idea to me.

All the best,

Peter

 

[fatjay]

10 year old system, i'm just looking to boost it a bit until i have the new system installed. It's on a pallet in my shop, i just haven't gotten there yet. Of course it's 95f out with a sudden heat wave now. I bubble tested and used my sniffer and no leaks detected, so i would imagine it's slow. I just want to top it off for now.

 

[LouNY]

Top it off and it'll likely be good for a few years.

 

[2manyrocks]

Did you happen to leak check the unions that join the line sets in case they vibrated a bit loose?