Impact on Mitsubishi new heat pump installed without upgraded board and firmwar
I bought a house last July with a Mitsubishi heat pump installed in 2023. The unit would switch from heat to a/c willy nilly or wouldn't heat at all without a lengthy shutdown. I'd wake up early a.m. to find the bedroom at 42 degrees. It was diagnosed by the manufacturer as a bad board and bad valve. The cost to repair was quoted at 2800. The cost for a new unit with 10 year warranty was 4000. I opted new.
The new unit is model NTXMPH30A132CA per the HVAC guy.
The new unit was installed and immediately had issues. It would cycle to defrost every 15 minutes and then when it would switch back to heat the unit sounded like a utility pole transformer exploding and you could hear the sheet metal of the unit rattle. Apparently this was old stock and never received the new board and firmware update that a post referred to in 2024 as being needed. Mitsubishi said the valve was decompressing too quickly per the HVAC guy.
This was so loud that it would wake me up. It then took two weeks for the new board to arrive, be installed and the firmware updated. It seems to run fine now, but….
Common sense suggests that the operating system was "pounded" for two weeks (in very cold CT weather) and there might be damage to the valve(s) that will haunt me down the road. Will it be a short or long road, we don't know. Does this sound like a legitimate concern? Or am I missing other concerns? I will also mention the intensity of the explosion seemed to diminish over the two weeks which makes me wonder if a seal related to decompressing suffered damage from the constant decompressing at too quick a rate.
I haven't paid the bill yet because of this issue and am reticent to do so without some further written assurance from Mitsubishi.
Thoughts please. Thanks!!!
Comments
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this a sounds very suspicious.
the defrost cycle shouldn’t be that long.
find a different contractor pull and weigh the charge0 -
I forgot to mention that the unit wasn't shipped full as it was supposed to be. it only had 3.5 of the 8 pounds refrigerant. they were added a couple days after installation.
the question is, was anything damaged during the two weeks of malfunctioning?
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i'd be more concerned about where the 4.5# of refrigerant went.
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Running 2 weeks low on charge.
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no leaks present. shipped from factory with partial charge.
again….what could have been impacted?
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are you sure it didn't leak out of the condenser somewhere while it was sitting?
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I find that hard to believe.
no compressor cooling.0 -
pecmsg…. the obliqueness of your comments leaves me flummoxed
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he says i think the same as me, if the condenser arrived with a partial charge it probably has a leak in it from the factory and it escaped while it was in storage.
the compressor is cooled by the returning suction side vapor, if the charge is low, the compressor cooling is poor.
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I'm not sure if mitsu uses these but the brand I stock has a little fusible plug safety on the outdoor unit. It's like a half inch long hexagonal brass plug with a hole drilled in the center and filled with solder. We had a run of bad ones on units straight from the factory around the time your unit would have been built, it might be worth checking.
I have occasionally seen units shipped with the incorrect charge but its pretty rare, and even harder to confirm as the units have always been installed when they are found. All but a couple low charge ODU I have seen from a factory are the result of a leak (or were install error and not really low from factory) It's rather difficult at most of these factories to just have the wrong amount of refrigerant put in, The only time I have seen that the label matched the incorrect charge amount because the label prints out what the factory programmed their machines to actually put in the unit. Its not impossible, just pretty unlikely. A leak is far more likely, something knocking around in shipping etc.
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what
Mitsubishi shipping a system low on refrigerant?
I highly doubt it!
I will bet this system will be short of refrigerant in the near future!
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Well, if the 10 year warranty has no deductible I wouldn't worry too much about it, but make sure you document the low refrigerant issue on install and make sure it's registered with Mitsu properly.
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yes, it arrived with partial charge. leak test done after filling to proper poundage and no leaks. we'll see what the future offers up pecmsg and mattmia2.
thanks ggross, that is good info! especially the possibility of installer error. and who admits their mistakes these days? few if any.
maxmercy, the replaced unit was only 3 years old and the warranty only covered the board, not the valve and not the refrigerant I was told. so the mitsu warranty ain't worth much it appears.
and of course there is always the possibility that my hvac guy fed me compost about everything. he's new to me though he is blessed by the Overlord, Eversource (aka Everscrew)
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how was it determined the outdoor unit was short of refrigerant?
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voodoo
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once they opened the valves the leak could be anywhere
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