Check the 24 volt wiring from the T-stat to the outdoor unit. Make sure the T-stat is actually calling for cool.
SOURCE: no cooling after power out, indicator lights pattern not in manual
The Mitsubishi units have to be reset by turning off the indoor units by switching the remote or thermostat to off. Then turn off the breaker to the outside unit(s). After 30 seconds,turn on the breaker and then you can turn on the remote for cool. If no lights come on on the inside units, most likely you have blown a fuse soldered on the main PC board. At this point, call your technician. A goos tech will be able to wire in an in-line fuse holder so if it should happen again, you can easily replace the fuse. If you do see a light or two come on at the indoor unit but the outdoor unit does not start after 3 or 4 minutes, sounds like you will need to call a technician. Most likely you have a blown fuse on the main PC board of the outside unit. It is not an easy one to replace. Good Luck!
SOURCE: mitshubishi split muh-18nvand inside msh-18nv
-Start the unit.
-Press EMERGENCY OPERATION switch.3-minute time delay works.Test run operation operates for 30 minutes.
-Check voltage to terminal block of outdoor unit.Is there 12V DC between 2-1?
-If voltage is presenet check the wiring, compressor contactor outdoor fan motor and compressor.
-If no voltage check voltage to terminal block of indoor unit.Is there 12V DC between 2-1?
-If if voltage is present re-connect the continuity of indoor and outdoor unit connection.
-If no voltage replace the indoor electronic control P.C.
board.
-But also check the coil thermistor sensor and room air thermistor if this two is out of range it can cause the tripping of out door unit. It has the resistance of 8 to 10 k ohms at 25 deg c temp.
SOURCE: duo-therm by dometic ac rv unit
I suspect that you have a bad selector switch for the on, off, low fan, high fan operation. If the selector switch is put into the off position everything should stop completely.
SOURCE: 2 problems.. AC Comp cuts out. And Fan will not stop.
Unit#2 -Sounds like the contacts on the master switch are welded closed or the switch is broken, Replacing the switch should fix this unit.
#1 is a little more difficult to diagnose. The compressor is being taken off line by a circuit that protects the compressor from damage either; 1- liquid refrigerant getting back to the compressor which can be caused by something as simple as a clogged return air filter or evaporator coil on a heat pump or 2- overload situation caused by a bad condenser motor or a clogged condenser coil. The first thing you need to do is clean both coils and replace the filter,. Then check to be sure your getting good airflow across both coils. I think it's most likely an airflow issue I hope this resolves the problem GL!
SOURCE: Blowing hot air, compressor not kicking on, just fan ? ?
are you speaking of the outside fan or inside? compressor should be a little warm but not boiling hot. the unit could be low on freon. if low it will run a while but the compressor will overheat and shut off leaving the fan running by itself ouside. if nothing outside is running check power. if you have power check the contacted outside to make sure it's pulled in. contacters are bad about going out on goodman untis. Also ants can get under contacts.
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