Built a new house 2 years ago, and decided to go for a unique "his and hers HVAC system" configuration. Thus we have Mitsubishi minisplits for cooling, and radiant floor heat for heating, with a thermostat for each room.
The system looks somewhat like this:
The problem is that on a hot day, the cold air blowing from the indoor units gets progressively warmer as the day goes on. First thing in the morning, it's blowing out ice-cold air. (Usually the downstairs and 1-2 upstairs rooms are on). Then, as the day goes on, the air temp gets warmer and warmer, until it's basically room temp air and no cooling is happening. At this point, you can even see that the indoor unit vanes are not "pointed down" anymore, but are pointed more up.
Turning off all the head units, waiting 30 mins, and then turning them back on will resume the cooling.
The original installer is not working anymore, and we've had a few techs come out, and they have no idea. There are no error codes being thrown on the compressor, but we have not been able to check during a period of outage.
Any ideas?
The system looks somewhat like this:
- 48k outdoor Mitsubishi unit
- 5 indoor wall mounted ductless units for the upstairs (9, 6, 6, 6, 6k)
- 1 ducted split unit in the crawlspace for the downstairs. (15k)
- 2x 3-way branch boxes
- 6x Mitsubishi PAC-US444CN-1 connected to Nest thermostats, one for each head unit. The Nest then connects to a TACO controller for the radiant heat part.
The problem is that on a hot day, the cold air blowing from the indoor units gets progressively warmer as the day goes on. First thing in the morning, it's blowing out ice-cold air. (Usually the downstairs and 1-2 upstairs rooms are on). Then, as the day goes on, the air temp gets warmer and warmer, until it's basically room temp air and no cooling is happening. At this point, you can even see that the indoor unit vanes are not "pointed down" anymore, but are pointed more up.
Turning off all the head units, waiting 30 mins, and then turning them back on will resume the cooling.
The original installer is not working anymore, and we've had a few techs come out, and they have no idea. There are no error codes being thrown on the compressor, but we have not been able to check during a period of outage.
Any ideas?
source https://hvac-talk.com/vbb/showthread.php?2222156-His-and-Hers-HVAC-system-Mitsubishi-Minisplits-Eventually-Stop-Cooling&goto=newpost
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