I have a Mitsubishi Mini Split system. A 3-ton heat pump and 4 indoor air handlers. The system was installed (self) and assisted by a qualified tech for some aspects. The system is in a new construction addition and has not been used for a couple years. After initiating the install the units were checked to make sure they were operational in the air conditioning mode and all worked as intended. Now that I am continuing the construction project and winter has arrived I needed heat in the areas. To my surprise they would not heat. The remotes are initiating the air handlers and louvers are operating but after a few minutes the operational display light begins flashing. It will not start up the heat process. The breaker and disconnect is allowing power to the unit and the wiring is correct. Is there a reset for the outside unit? I have called the serv tech that finished the installation and have been unable to contact him. Any suggestions? I am a DIY (advanced for a lack of terms) and did the majority of the install which was double checked by the "tech" and approved.

 

The charge could be incorrect. These units are critically charged and to verify that the charge must be pulled and weighted.
What error is showing?
These units are not for dusty conditions and will not handle a construction environment very well.

 

Haven't looked at the Control Board (?) of the outside unit if that is were the error would appear. They have not been operated in dusty conditions. They have not been run while construction was done but covered and wrapped to prevent the dust in the unit. The charge that you are referring to is the 'Freon" I assume. It was done by a Air Conditioner Technician and I am sure he knew what he was doing. All was vaccumed and charged with factory Freon supplied

 

“Factory supplied” is just what came in the outdoor unit. Removing or adding to that is required based on lineset length and indoor unit selection.
It should all be covered in the install manual.

 

I had more explanation in the reply but it was not included. If the operational light blinks it recommends a wiring error which is doubtful as I was standing next to the tech making sure it corresponded to the indoor units wiring. If all the indoor units worked in the air conditioner mode would that not indicate that the charge was correct? It also mentions a SW871 switch on the outdoor which is suppose to correct wiring & piping functions. Is this something that I should attempt?

 

It did fall into the OK range when it was compared to the length runs.

 

I don’t know anything about that switch. But port addressing should be done during commissioning.

 

"port addressing" ?? I couldn't find anything concerning that operation

 

Each indoor air handler must be addressed properly. It’s been a while since I did a Mitsubishi, I can’t remeb the process.
What’s the model number?

 

The outside unit is MXZ-4B36NA. I have 2 MFZ-KA09NA floor handlers and 2 MSZ-GE12NA wall handlers.

 

Correction on the outside unit. It is a MXZ-5B42NA.

 

What gauge wire was used between the outdoor and indoor units?

 

It was a regular wire set matched to the unit by the supplier.

 

I had to go back and check but I believe it was 14-4 ga. Mini Split Wire

 

roughneck I took the cover off the outside unit and there are only 3 led bulbs. Red, yellow and green. All will initially be constant. Then green will go off and flash 10 times then return to constant on. This pattern repeats. I get the same pattern even when I use the remote and turn on the heat cycle.