Mini split will cool in "cool" mode, but won't cool in "auto" mode

dalegribble · Apr 21, 2023

Mini split will cool in "cool" mode, but won't cool in "auto" mode

Mitsubishi.

If I set to 22 degrees C and put it in auto mode, it'll run for a bit but blow hot 30 degree C air, and then the compressor fan shuts off. if I turn the remote down to 19 C (66 F) just to test it, the two green lights will come on to signify it has not reached the desire temp, but after a minute the outside condenser fan will shut off.

However, if I put it to 22 or 23 in "cool" mode, it will cool really well and keeps going. So I can't see it being a refrigerant issue.

House is 24 degrees inside (75 F).

I recall trying it in auto mode in the dead of summer and it didn't seem to work in cooling anything, so I have always put it in cool mode.

pecmsg · Apr 21, 2023

What does your service provider say?

hvacvegas · Apr 21, 2023

Do you have multiple units hooked up to the same outdoor unit, and is the other unit in heat?

dalegribble · Apr 21, 2023

hvacvegas said:
Do you have multiple units hooked up to the same outdoor unit, and is the other unit in heat?

Two units hooked up to the same outdoor unit. I have one on auto mode right now and the other one is turned off.

pecmsg said:
What does your service provider say?

They told me to use cool mode because auto will cause the units to interfere with each other so I'd been using cool. I tried the auto once and it didn't cool so I stopped because I thought I was doing something wrong. I am getting it serviced soon so I will ask.

hvacvegas · Apr 21, 2023

It can cause whats called mode conflict, if you have a unit in auto with multiple heads.

These indoor heads are kind of a universal head. So the options that are there, may not work with every combination.
Same thing with remotes.

Im using a remote from a 2017 fujitsu, on a 2010 fujitsu. Completely different models, and options. But it turns it on, heats and cools.

Personally, your and my version of auto, is different from asian version of auto.

Some mfgs are using 8 degree "swing".

As far as why i asked if the other is in heat.
Being a multi head unit, if one head is in head, hot refrigerant is sent to ALL units.
If the fan is blowing, hot air will come out.
The one not "calling" for heat, will have very low fan, but MAY overheat, as a side effect.

vstech · Apr 24, 2023

Dammit Dale!

Sorry… had to do it from your username.

jacob-k · Apr 25, 2023

Can not use auto mode with multiple head units. Not even if only one zone is running.

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Mini split will cool in "cool" mode, but won't cool in "auto" mode

dalegribble

pecmsg

hvacvegas

dalegribble

hvacvegas

vstech

jacob-k

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