Chigo split unit cycling - is this normal?

[et0]

Hi all, I'm hoping someone can help me understand this:

Chigo 24kBTU non-inverter split-unit, with reversing valve.
In heating mode, it starts up and produces heat, but the compressor only runs for a few minutes then it shuts down. Then the indoor unit blows cold air for a while and then the fan stops. After another few minutes the compressor starts again and the cycle repeats.

As well as being annoying, it seems very ineffective - it never reaches the 21C setpoint. No fault codes though.

Any idea what could be wrong or what I could check? Surely it should work better than this? I have just downloaded and read the service manual but it hasn't helped much!

Thank you :)

[chillerman2006]

Hi et0

take all the running temps & pressure, tubework/air .....

then if not resolved, post them here mate & someone should spot the problem

lp failures dont show up on some controllers as often auto reset

R's chillerman

[install monkey]

is the compressor seizing, clip and moniter the running current of the compressor only and compare it to the dataplate-for the locked rotor amps=lra

[mad fridgie]

I would say incorrect application, in my experience these chigo units are best suited as "small boat anchors" "fresh water only of course"
But if you must insist in using for applications, i would first determine where you are loosing the power to the compressor motor. Check at compressor terminals, if power is still on, then is off on its internal overload, and nothing much you can do about that (return as an anchor) if power is not at the comp terminals, then it is a control issue. If I remember rightly these are controlled by the indoor board only. Note check that the air sensor and coil sensor are not reversed (coil sensor reading air and visa versa).

[paul_h]

Sounds like it's running on thermostat normally, ie cycling normally but reading the wrong air temp.
If comp fault it would have cut out on overcurrent fault (if the PCB measures current), or cut out on the compressors own overload eventually.

Check airflow (filters, fan speed) etc and is the indoor unit jammed up in the corner and right up tight against the ceiling, or some crappy install position like that?

Check thermistor isn't touching the indoor coil. Since you have the service manual, check thermistor resistance against temperature and what is in the manual.
If everything is OK, I suspect PCB fault.

Edit: How did in run in cooling mode? If perfectly fine, then I'd go with PCB fault.
Cheap chinese a/cs have horrendous spare parts costs though, (that's if you can get them), so I'd probably replace the unit myself with something decent, rather than replace PCB.

[et0]

Sounds like it's running on thermostat normally, ie cycling normally but reading the wrong air temp.


Bingo! Got the same thought yesterday and tried it when I got home.

Looks like the Rt thermistor is a bit out, or there's a trim-pot needs trimming. Setting the control to 28 gives me a 20C room temperature quite quickly (starting at 13), and the compressor stays on until it gets there, so apart from that it's actually working fine I think.

Rather obvious now, why didn't I just think to turn it up?
Thanks for the help everyone. I'll report back on how it works (or not) in the cold weather..

[paul_h]

If I knew you weren't a fridgey, I would have told you to set the set point higher in the first place. I assumed you tested this at higher set points.
Oh well, then like I said before, possibly poor location for the indoor unit, possibly you aren't running it on high fan speed (definitely better to improve air flow over the sensor and keep the indoor coil at lower temps), and have the louvers pointing down. On cheap units their control system isn't so good, they don't compensate for the fact hot air rises and the thermistor reads higher than room temp actually is. The whole situation is only made worse because people with cheap units want cheap installs. So poor location and maybe too short a pipe run is common,. which affects heating more than cooling.

So point louvres down, crank up the fan, and set temp set point higher than desired to achieve room heating.

Had a guy call me up a few months ago saying the indoor unit on a cheap chinese unit dripped water in summer on cooling mode, (even though the drain was clear etc).
Sure sign of the system being about ~5% short of refrigerant. Leak repaired, evac and charged. A few weeks later he called with the same complaint as you. Well now it's got a full charge, the indoor coil is going to be a little warmer than before, so told him " point louvres down, crank up the fan, and set temp set point higher than desired to achieve room heating." due to the corner location of the indoor unit, and it's cheap/poor design lacking compensation for heating.

[et0]

Hi Paul,
Yes. This cheap-o unit has only one fan speed: flat out.
And the indoor unit location is non-standard but I did measure the intake air with a thermocouple while it was blowing warm shortly after starting - 14 degrees - I don't think it's recirculating...

Yeah - confession, I bought this on ebay and installed it myself, so it's a bit cheeky asking you blokes for advice - sorry. I'm learning though, and can provide you with some cheap laughs and told-you-sos when it all goes wrong ;)

[paul_h]

Chigo make fancy inverters here.
Chigo themselves think they are pretty good LOL http://www.chigogroup.com/en/default.aspx
We get all the junk from asia, there's at least 25 crappy chinese brands around. That's not including the euro or japanese brands that stick their name of some cheap chinese rubbish (not including the designed elsewhere but made in china - every main brand does that these days - I'm talking about you can tell it's designed in china with as well)
I've only seen one chigo a/c and it was an inverter. Diode bridge shorted out (happens a lot with fujistus too), soldered in a new one and off it went.
Soldered in a new one because like I said before, PCB cost twice as much as a japanese brand, total rip off for spare parts. If you are going to go cheap a/c, at least buy korean, parts are laughably cheap and a little better designed than chinese, a little better.
Myself, I only sell and install panasonic and mits heavy industry (MHI). Use to do warranty for pana, saw 1 of them for every 10 of other brands fail, and most pana failures were install or rodent caused. Never had a faulty unit from pana or MHI from all the ones I've fitted ever.

[et0]

If I get PCB / electrical problems, I can handle that, it's my day job :)

This unit proudly says "TOSHIBA compressor" all over it, so I figured it might last. Slightly regretting not having an inverter unit though.


And I must admit I was expecting a quick-connect coupler for the refrigerant lines, as it was "DIY Easy Install". But what I got was flared pipes, and an instruction about bleeding air from the service port for 5 seconds...
I ignored that and borrowed a vacuum pump instead.

Anyway, quite pleased with how quickly it got the room up to temperature while consuming 3kW.

[Mick13]

i am so glad to hear you borrowed a vac pump :) that brightens my day....

purging is something im highly against, as any good fridgy should be, i know other techs that purge, and its something i have never done, and never will do

so im glad to hear u had the sense to vac it properly!

[firey1]

Bet he never used a vacuum gauge to verify holding vac after pressure testing. No point running a pump sucking in air through your leaks for 20min anyway.