Fault on AC unit, advice please

[MF88]

The boss has asked me to look at a fault on an AC unit in one of the offices we look after. I've never carried out fault finding on an AC unit, only ever wired the supply to them, so I'm a little stuck at where to go to next.

The indoor unit is - Mitsubishi PLA-RP-BA(2)
Outdoor unit is - Mitsubishi SUZ-KA71VA
Wired remote controller is - Mitsubishi PAR-21MAA

The user reported a fault on it this morning. The panel of the wired remote controller is just blank.

I'm supposed to have 12v DC at the controller and I've got nothing. I do however have power first to the outdoor unit and also power at the indoor unit.

There's a few LED's on the circuit board, all of which are off, but "LED1" flashes quickly once every 30-40 seconds.

Any ideas please?

 

[telectrix]

i would seek the obvious. find the 12v tranny and work from there. a blown fuse is likely

 

[Marvo]

Make and model number of the A/C unit might help.

Check all the obvious first, it might have a manually resettable head pressure switch on the condensing unit. If something has tripped then reset it and switch off power for 30 secs and switch back on again.

Edit. Sorry, didn't see the make and model no in your OP.

 

[grantr37]

The boss has asked me to look at a fault on an AC unit in one of the offices we look after. I've never carried out fault finding on an AC unit, only ever wired the supply to them, so I'm a little stuck at where to go to next.

The indoor unit is - Mitsubishi
Outdoor unit is - Mitsubishi SUZ-KA71VA
Wired remote controller is - Mitsubishi PAR-21MAA

The user reported a fault on it this morning. The panel of the wired remote controller is just blank.

I'm supposed to have 12v DC at the controller and I've got nothing. I do however have power first to the outdoor unit and also power at the indoor unit.

There's a few LED's on the circuit board, all of which are off, but "LED1" flashes quickly once every 30-40 seconds.

Any ideas please?

power supply for controller panel dead, aircon unit gone into standby mode......you need to check the 12 Volt DC supply to the keypad, this comes in the back via the wired connection to the indoor ceiling unit.....check the connections for movement....

 

[grantr37]

use multimeter on the PCB in the ceiling unit behind the outer cover, check for 12 volts there between the pins which are labelled on the PCB in white text....

 

[Gage]

tranny and work from there.

whoahhhhhhh!

 

[big-steve]

Indoor unit pcb has a fuse on it it's most likely that that's blown! If not their should be terminals on the indoor unit, ( you have to drop the filter diffuser if its ceiling mounted) usuall labelled p1 + p2 you should get a dc voltage (24v i think) between them! If so take the controller off to access the back if you have a dc voltage there and all connections are sound, controllers faulty

 

[FrankUK]

LOL....keep it up guys, you're killing me....stick to the electrics and leave the A/C stuff to professionals.

 

[FrankUK]

This might help you...

 

[big-steve]

Is that what you are then frank?

 

[FrankUK]

Yes Steve...see my profile

 

[ian.settle1]

Make and model number of the A/C unit might help.

Check all the obvious first, it might have a manually resettable head pressure switch on the condensing unit. If something has tripped then reset it and switch off power for 30 secs and switch back on again.

Edit. Sorry, didn't see the make and model no in your OP.

Should have gone to SPECSAVERS