AC HI/LO on condenser and evap fans. - Printable Version
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+--- Thread: AC HI/LO on condenser and evap fans. (/showthread.php?tid=8500)
AC HI/LO on condenser and evap fans. - Gem930 - 06-26-2025
I'm currently working through some AC issues. My ultimate plan is to install a mini split in the front and keep the rear working for as long as I can. I have a trip, coming up however and I'm trying to cobble somnething together usind the high current relays as others have done. My problem is my thermostat and/or board are doing strange things when it comes to HI/Low. I can work around that as well by wiring up only high, but I am trying to understand exactly how the system is suppose to work (in referance to the HI / low fans and one vs. two compressors). In low is only one compressor supposed to work? Is the wiring on the cond/evap fans high /low windings or additionaly fans? If it is higher speed windings are both the high and low windings energized on high or only the high????
Thanks in advance for any information.
Gregg Miley
530-228-5399
RE: AC HI/LO on condenser and evap fans. - Richard - 06-26-2025
If the tstat is set on low, only one compressor will come on.
If set on high, both compressors are powered.
HI/LO seems to make no difference on the indoor fan speed. Even though the motor for the indoor fan has two sets of windings, the real culprit is the indoor fan is controlled by the fan circuit on the tstat, and those tstats activate the same indoor fan speed irregardless of the hi lo setting.
When the 2nd compressor activates, you should notice a substantial difference in the outdoor fan.
You are not losing your mind, it took me years to figure that one out.
RE: AC HI/LO on condenser and evap fans. - pairodice - 06-26-2025
Where are you going to install the indoor portion of the mini-split? I love the idea of a mini-split but don’t want to ‘see’ the unit or have to build it in too much… I’m fighting through the same issues with NO A/C working currently… Jeff Lojudice (sp?) is helping me with my system and sent diagrams and how to wire up relays if you want some help with that portion of it… these fans are wierd…
HoosierDaddy - HoosierDaddy - 06-26-2025
This is how I mounted two inside air handlers. They are made by LG
RE: AC HI/LO on condenser and evap fans. - Gem930 - 06-26-2025
That looks great!. Since I am taking my TV down from the front, I am mounting this inside unit there. I found a fet black ones that will blend right in.
As far as the temporary set up for my front unit, I determined (after the explanation from Richard) that while my tstat is calling for hight with 12v to the correct pin, the board is not turning on the second compressor of turning the fans to high. Not hard to work around especially since this is only temporary and I dont care about having a low setting. Ill just swap the hi and low wires in the fan pins and control both additional compressor relays with the power from the compressor that does come on in the low setting.