Problems with my Fujitsu mini-split??
Last Post 30 Nov 2015 10:38 PM by Toadman. 15 Replies.
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pbraneUser is Offline
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22 Nov 2015 07:19 PM
Hi all.. I'm finishing up my new, small, super-insulated house in zone 6 and had my 12RLS3H installed a few weeks ago. We've finally had some cold temps and am concerned. One problem is that the set temp (on wireless remote) has to be set about 10 degrees higher than desired room temp. I tried to program the function and settings to compensate, but it won't accept the command (no beep). Also, it seems to short-cycle too much, even when I set the temp way up. I'm not sure what "normal" should look like for these things. Not getting much help from Fujitsu and my installer doesn't have a lot of experience with them. Anyone else with some experience with fujitsu units? Thanks much for any help! michael
ronmarUser is Offline
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23 Nov 2015 10:34 AM
A little hard to troubleshoot like this, but lets see if we can separate between a setup issue or a failures. To do that we need to establish what modes/settings the unit is currently operating under. In your manual there should be a section describing every possible display on your controler screen. I need you to list everything shown on the display?

Short cycling can indicate a few things.
1. Incorrect setup.
2. It is oversized for the aplication. What is you square footage, outdoor temp and insulation value? If I am reading correctly that unit outputs around 12,000 BTU.
3. The thermostat is placed too close to the unit and it is doing exactly what it is set to do. If there are multiple rooms,where is the unit located in the floorplan, and how are you dispersing the heat to the rest of the house?
4. It has an issue and is shutting down under failure, resetting and repeating this process...
patonbikeUser is Offline
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23 Nov 2015 11:42 AM
I think you know this but I didn't realize it at first - you need to point the remote at the unit with line of site, and hear the head beep or, it's not receiving the command. I Was trying to turn the heat up and it wasn't doing anything because I had the remote in another room.

How much clear space is in front of the unit (i.e. is the hot air bouncing off a wall in front of the unit and going back to the unit)? I pointed the louvers far left to try to direct some of the air up the stairs. about 13 feet away in front of the unit is a wall that I didn't want the hot air hitting and returning immediately to the unit, telling it to stop or slow down heating.

How close is the head unit to the ceiling?

Where are you checking the room temp compared to the head unit?

Programming might not necessarily be what you want. I think in a lot of cases you will want to pick a temperature that is comfortable for you and leave it at that. Setting it back at night or when you are at work might be counter productive.

Dana1User is Offline
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23 Nov 2015 02:53 PM
When the head is mounted close to the ceiling the intake air temp that it's sensing is MUCH warmer than the average room temperature. You may need to install a wired remote thermostat to the head to get the temperature levels to track reasonably and stop the short-cycling. See:

http://www.fujitsugeneral.com/wired_remote.htm

Either that, or move the head lower, which would enhance both heating efficiency & capacity. In a heating dominated climate such as US climate zone 6 it's better to mount the thing well below the ceiling (or even close to the flloor), since the extra-warm intake air near the ceiling makes it somewhat less efficient, and limits the overall capacity. Mounting near the ceiling makes great sense for air-conditioning efficiency & capacity, but in zone 6 your cooling degree days are an order of magnitude lower than your heating degree-days. The HSPF efficiency testing presumes a maximum of 68F intake air, which isn't usually found anywhere near the ceiling in a 70F room, or even most 68F rooms.

http://www.greenbuildingadvisor.com/sites/default/files/Peter%20Talmage%20%20-%20ductless%20minisplit%20mounted%20low_1.png
pbraneUser is Offline
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23 Nov 2015 09:08 PM
Hi Ronmar... Not sure what you want me to list on the screen of the remote, but I have it set to heat mode, fan usually on auto. House has 2 stories, 400 interior ft2 on each floor. Unit is on first floor, which is basically one big open room. Walls are about R-40. Tight construction. Thanks for any further thoughts. -m
pbraneUser is Offline
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23 Nov 2015 09:15 PM
Hi Paton.. Yes, I;m able to send temp commands etc and the untit always beeps. But not when I try to get into the function settings (which is where you set temperature correction). The unit just will not take a command in function mode. The wall in fron of the unit is about 16-18 feet away, and there's a stairs leading up. I'll see if I can direct the louvers in a different direction. Unit is probably too close to ceiling at about 2.5". I'm checking all over the house with different thermometers. I'm not trying to set a "program," but rather do a temperature correction, since the thermostat is inside the wall-hung unit and not in the wireless remote. Thanks much. -m
pbraneUser is Offline
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23 Nov 2015 09:30 PM
Hi Dana.. I'm starting to realize the unit should have been lower on the wall. Nobody mentioned there would be a problem. My installer didn't say anything and I hadn't read anything about the potential for short cycling. Too late to move it, at least for now. Don't wanna rip my walls apart. I asked Fujitsu about a remote thermostat and the guy said no, there must be a problem with the on-board temp sensing and I should gt a tech out to troubleshoot. And I didn't think any of their remotes had temp sensing on them, but I see the one you linked to says, waaaay at the bottom: "Remote temperature sensor." The cheaper one doesn't have that. I'll call about it tomorrow. Thanks much. -m ps. Would still like to know why my remote won't let me change function settings.
ToadmanUser is Offline
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24 Nov 2015 03:03 AM
Try putting a thermometer some where near the unit. I put mine right under the unit but so the air didn't hit it. I found out with a thermometer that the temperature falls so quick after it turns off. I just need mine to quit ramping up some and stay at a lower temp.
ronmarUser is Offline
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24 Nov 2015 09:49 AM
The reason I asked about the displayed icons, If I read correctly, that unit has a mode where it will alternate between heating and cooling mode automatically based on temperature shifts. If this were engaged, and the unit is reaching and exceeding set temp, it may be shifting to cooling mode briefly.

If what you described is all you have set, then that is probably not the case.

With fan on auto, I wonder how high it is actually running? Have you tried setting the fan on low to see how this effects operation? This should slow the heat delivery and might extend the run times and allow the heat more time to disperse into the room.
pbraneUser is Offline
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24 Nov 2015 10:20 PM
Hi ronmar.. Actually, it was suggested to me to put the fan speed higher to get the heat spread around the room better. It does seem to help. And I FINALLY got into the function settings. The 10th time I called Fujitsu was the charm. A guy told me the unit has to be OFF for it to take the commands. We'll see if the temps are more aligned now. But it will probably still short-cycle because of the placement of the unit to high on the wall..... -m
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25 Nov 2015 05:30 AM

I do have 1 question while n the topic of these units: Every once in a while I notice the louvers go up. And it seems to "rest" for a while, the green light is still on, then goes back into normal operation. 2what is it doing? Is it defrosting or something?
ToadmanUser is Offline
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25 Nov 2015 11:07 AM
Is it around or below freezing? If it's in defrosy you will hear a swishing sound and no air will be venting. My fugitsu has the like blinking but the mitibushi doesn't. If there is air blowing out then it reached its desired temperature and just idle.
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25 Nov 2015 11:08 AM
Is it around or below freezing? If it's in defrosy you will hear a swishing sound and no air will be venting. My fugitsu has the like blinking but the mitibushi doesn't. If there is air blowing out then it reached its desired temperature and just idle.
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26 Nov 2015 03:41 AM
I've been playing around with the blower settings and vane settings. I always leave the vane toward the floor . I decided to try it to the swing setting and for the past 1.5 hrs it hasn't shut off and holding a steady temperature at the intake of the unit. The drafts I was getting were the short cycling problem and at least for tonight its working like it supposed to.
patonbikeUser is Offline
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30 Nov 2015 11:22 AM
I have seen the blinking light with the louvers up, but I've also seen solid green light and the louvers go up.

If it it just idle/reached set temp, then the louvers should not go up (I don't think).
ToadmanUser is Offline
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30 Nov 2015 10:38 PM
The fugitsu and mitibushi models I have both leave the louvers in the up position when they are idle. The solid light is in operating in any mode. Mines a fugitsu rfflh model.
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