Mini split head blowing cool air
DIYJester
| Posted in Mechanicals on
I have 4 half ton heads and a 1.5 ton head in my house that were recently just commissioned. One head seems to blow considerably cooler air than the rest. I have checked almost 100% of the lineset into the unit from the branch box and we no kinks. The branch box does recognize I have 5 heads hooked up. It did seem like it was blowing a bit warmer when it was the o my head running.
Any ideas? Thanks in advance.
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I don't have a ton of experience resolving this kind of issue, but here are a few of the things I would check:
1. Refrigerant lines 100% leak-free.
2. Lineset lengths and connected capacity within manufacturer's specs.
3. Correct additional refrigerant charge weighed in.
4. Control wires not crossed/branch box addressed correctly.
5. Correct wire gauge and type used for control wiring. For example, if the instructions say 16/3 don't assume you can upsize to 14/3.
6. Check for stored error codes on indoor and outdoor units.
7. Indoor fan speed set to "auto."
Jon,
Thank you for the feedback. I've checked all of those things and couldn't find an issue. On Mitsubishi heads you have 220v coming in and a signal wire. All looks good on that end. I have no error codes that I can tell either.
I may have to try to run the compressor through its trouble shooting and see if I get anything that way.
Ok, so this head is at it again. I realized that after I reset the head it seems to blow warm for a little bit, but normally cannot meet demand. The unit is a Mitsu FH 1/2 ton head, oversized for the room at full run, but within its modulation range. These units have 2 lights, one for running within 2 F of setpoint and one between 2-4 F between setpoint. This is the only head other than one covering an area with un-insulated floor and ceiling that has had an issue. All of the other 4 heads regularly meet demand and keep the rooms warm, blowing warm air. This head seems to just blow cool air all day and says its below setpoint.
Are there any settings I should address? This is one of 5 heads in a 3.5 ton system. All the other heads seem to work ok. I cut back most of the insulation on the linesets and cannot find a kink that would possibly cause a low refrigerant flow.
Any help would be great. The start up company didn't know much about the units at all. They basically just did the charge and couldn't help with the issues. The other local companies don't want to provide help as they didn't do the install or start-up, which is very frustrating.
Thanks,
Mike
Mike,
The installation company can't walk away from their responsibility on this problem. If you aren't getting satisfaction from your contractor, call Mitsubishi.
Martin, thank you for your reply.
Jon, on second checking the units after realizing my office was overheating with the head off, I realized the the installer did end up crossing heads B, C, and D. Apparently having the wires taped to the heads wasn't enough. Around here it is extremely hard to find contractors to perform an install and commissioning of a system unless they sold the system to you marked up 30-40%. I understand they need to make a business, but if the only labor they have is terminating wiring and line sets, and charging $30 a pound for refrigerant that costs about $6 a pound, I don't understand why the just don't have an hourly service fee like a commercial or industrial boiler company would.
Again thank you for the input. Also, Martin, I did get a hold of Mitsubishi and since I am also a licensed tech they were able to give me more information than a regular homeowner. The tech on the phone did say that the U shaped routing of the line sets may cause an oil trap, but 4/5 heads have been operating well and the compressor still appears to have oil with these configurations.