Mitsubishi 8-Zone M Series, Climate 2B or HOT
Hello, long time stalker, first time poster.
I am in Central Texas and have an 8 zone Mitsubishi, MXZ-B48 Outdoor, 3&5 port branch boxes, all GE wall mount indoor units 15/12/12/6/6/6/6/6.
When first installed everything was 90% amazing. The rooms that were cooled by this system were cold and dry. The condensate lines would pour out water. The only issue we had at the time was that the bathrooms and hallways were hot, especially right after showering. I installed 6″ jumper ducts with inline fans but it still was very uncomfortable in these areas. My contractor(father in law) decided we should put in a central system to handle the bathrooms, hallways, and the main living area. A 2 ton heat pump system was installed, and it works great.
Going into the 3rd year with the system, we began noticing that the smaller bedrooms(6K heads) we very humid, and the 2 rooms with the 12K heads were not getting to their setpoint.
My father in law is a 40 year HVAC guy, but is not incredibly versed in mini’s.
This is what we have done so far while working with Mitsubishi Tech support. We have not seen any positive results and are getting frustrated.
1. Recovered all refrigerant.
2. Cleaned all coils/blower wheels/drains/drip pans
3. Pressure test w/ bubbles and sniffer to 550, no leaks
4. Pulled Vac and triple evacuated
5. Weighed in exact amount of Virgin 410A required
System is still not cooling well but is doing some funny stuff. When the indoor units are set to COOL and the setpoint is pushed all the way down to 59, I am only getting a deltaT around 13. When I push the button on the indoor unit to place it into emergency cool I get a deltaT around 16, when I use dip switches on the outdoor unit placing it in test run, I get a deltaT of 21. This is the same on all the indoor heads.
Mitsu Tech support asked me to go through the entire system by flipping DIP switches to see if all the wiring was correct/if one head was cooling when it shouldn’t/essentially checking to see if an LEV was stuck. They warranty replaced the main board on the outdoor unit and this did nothing to remedy the situation.
Does anyone have any ideas what could be happening, outside the box thinking is appreciated. Very frustrating given how amazing the system worked the first 2 years.
Also I have had 2 “Diamond Dealers” on the property and quickly realized that I knew far more than they did, one was literally googling on his phone. He just started dumping 410 into it a pound at a time(part of the reason I started from scratch) The other admitted to me that he was the senior tech and only had training on minis with a 1:1 ratio and not multi-splits. Problem is these are the only 2 diamond dealers in the area.
Any help is greatly appreciated!! Thank you for reading.
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