20 Most Recent Mitsubishi MS12TN Air Conditioner - Page 6 Questions & Answers

Sounds like you have a power issue if all 3 goes out the same time

Sounds like the filter or coil is dirty, therefore fan amount up and hindering drainage. Vacuum drain, clean coil, change filter. If you need further help, reach me via phone at https://www.6ya.com/expert/thomas_092728000e6acb79

No it will not .Gist you have to check what is preventing the compressor. Those unit have a lot of safety so first thing reset the unit and you do that by shutting the power off then turn it back on .
You then look at the compressor to serve what it's doing .If it comes on and run for a minute then shut off again that means the coil is dirty so you should wash it .If compressor does not do anything then check the control board for any blown buss fuses.
If no bad fuses are found then you need to see if system have any freon (refrigerant) .If your guages is reading 0 or reading very low it means you have a leak and that needed to be fixed before your ac could work again

Sounds as if the 20's are set up to control humidity and the 40 is not. That is likely a setting in your tstat. Good Luck. If you need further help, reach me via phone at https://www.6ya.com/expert/thomas_092728000e6acb79

try switching to cool mode and try turning it on if this doesnt work unit may be blown.

Sounds like you're on the right track. Might as well replace the , inexpensive, gfi while doing so. With power off make sure all connections are tight. Electrical tape is a wonderful thing. Good luck!! If you need further help, reach me via phone at https://www.6ya.com/expert/thomas_092728000e6acb79