Mitsu MrSlim heat pump stopped working...any tips?

[JMURiz]

Looking for some DIY tips to get my 18k Mitsubishi MrSlim heat pump working again.

I used it for a couple years and this year it stopped working.
When I turn the unit on, the fan cycles and the outlet opens/closes (probably checking the systems?) and then the fan turns off and it sits there with a blinking light on the inside unit.

I've tried the cool/heat/dehumidier settings with the same results for all.

Is there a sheet of how to decipher what's wrong with my unit. I couldn't find anything in my documentation.

My hvac friend that helped install it moved away and would like to DIY fix it if possible. I don't like playing the 'Arlington price' for contractors

Thanks,

 

[mustangacman]

Might look here. Hope this helps.
http://airmaster.net/mitsubishi-air-conditioner-error-codes

 

[Jackfre]

What, if any, error codes are coming up? Are you running it for heat? If it had run for cooling, but not strongly, it may not run in heat. The pressures necessary for heat are substantially higher than those for heat. If there is a very small leak the problem will show in the heat mode. Learned that the heard way.

 

[chinboys]

It could be low freon level -safety interlock kicking in due to low-pressure detection in the liquid or gas side of the unit.

You will need to get a repair tech in to put gauges on to the system to confirm.

Or it could electrical ... no power in, start cap problems, etc.

 

[JMURiz]

I'll take a look to see if I can find any error codes this weekend.

I may also try to cycle off/on the outside unit just in case it has something to do with the inside/outside not 'talking' to eachother.

Thanks, and I'll keep you posted.

 

[theoldwizard1]

Standard house call is usually about $100. Or buy a set of A/C gauges.

 

[JMURiz]

....and 2 months later (yikes) I got some time to check on my outside unit.

Two mice decided to chew on some wires and get buzed. Looks like both of the wire harnesses have been chewed on and need replaced.

Where's the best place to get new parts for older Mr Slim units. Mine is a MUZ-A15NA (I think off the top of my head, it's the 18k BTU heat pump unit)

See photos: Looks like a fan wiring harness and some kind of temp sensor that clips into the black plastic cover on the unit.

 

[PoorOwner]

....and 2 months later (yikes) I got some time to check on my outside unit.

Two mice decided to chew on some wires and get buzed. Looks like both of the wire harnesses have been chewed on and need replaced.

Where's the best place to get new parts for older Mr Slim units. Mine is a MUZ-A15NA (I think off the top of my head, it's the 18k BTU heat pump unit)

See photos: Looks like a fan wiring harness and some kind of temp sensor that clips into the black plastic cover on the unit.

yes they are apparently temp sensor (thermistor)

http://meus1.mylinkdrive.com/files/MUZ-MUY-A09-24NA_GA24NA_Service_OB451G_6-11.pdf

Page 76, part 24 or 25.

if you put in the part number without the space there is 1 place listing it, some kind of supply house.
you may just need to call mitsubishi, hopefully they will help you. They DO NOT usually like to talk to you if you are not a HVAC contractor.

 

[Jackfre]

This may have shorted out the board as well. I saw this a number of times with snakes getting up into condensing units. They would get hit with voltage and roll and roll and blow everything. I would call your friend who moved away and see if he can source parts direst shipped to you. The factory folks really do not like talking to homeowners.
Your situation is one of the main reasons that I suggest condensing units not be ground mounted. To much rodent and reptilian exposure.

 

[JMURiz]

Thanks for the tips....looks like that grey wiring harness is connected to the fan motor as well.

GRRRRRR, looks like I'll have to replace that whole unit as well. Looks like from photos there is a harness plug, but I can't find the wire itself, only a part number for the whole thing.

So I'll probably need:
E12927308 - ambient temp thermistor
E12A54301 - fan motor and harness

Any ideas for mouse-proofing my ground mounted unit? Maybe a hardware cloth cage around any openings?
They can climb up 2 story houses into the attics of houses around me, so I don't think wall mounting would help much.

 

[PoorOwner]

Re: Mitsu MrSlim heat pump stopped working...any tips?i

Well you can repair the wires if you are on your own, anyway

But I would think the circuit board is damaged

You need to stuff the opening with something
Usually steel wool but it would make a mess here so you can use the next similar thing which is a 3M floor pad. They come around 12” circle. Usually the RED will do it. I cut them out to make my own synthetic Brillo pads

 

[PoorOwner]

This may have shorted out the board as well. I saw this a number of times with snakes getting up into condensing units. They would get hit with voltage and roll and roll and blow everything. I would call your friend who moved away and see if he can source parts direst shipped to you. The factory folks really do not like talking to homeowners.
Your situation is one of the main reasons that I suggest condensing units not be ground mounted. To much rodent and reptilian exposure.

I have mine on stands. Any pro who sees it ask me why, no snow here. They stay much cleaner and harder for creatures to get into. But no impossible for little lizards to go thru the lineset into the unit. I have not had any issues knock on wood. Seems like a draw of luck on these things and elevating it definitely less easy for creatures to get on the unit.

There is one at the mall I saw outside an elevator structure. It’s on the ground but not even bolted down.