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AY1014 fan speed control

Sergea29Sergea29 Member Posts: 22
Hello,

Would anyone be familiar with how the fan speed is selected for just fan, for heating or for cooling. I am not sure my a/c is using the high speed. The air handler is an AHG36-0A.

Thanks,

Serge

Comments

  • mattmia2mattmia2 Member Posts: 1,297
    edited June 27
    It would appear that it is selected with the dip switches.

    Er, never mind. Those actually are resistors, i just saw the actual pictures. they looked like switches on the "schematic" which only shows the board as a black box, is not an actual schematic.

    According to the schematic, high and low, red and black to the blower, are swapped.
  • EBEBRATT-EdEBEBRATT-Ed Member Posts: 7,041
    Looks to me like it is wired to run on low speed on cooling On the control board Black should be hi speed, red low speed and blue medium speed.

    So you should be able to swap the black and red wires,

    Red which is on high speed on the board, move the black wire to hi speed and the red to low speed.

    Check with a meter to make sure only 1 wire (black, red & Blue) is powered at the same time. Hi speed black for cooling, Blue medium for heat and the red terminal on the board is probably dead the wire just parks there
  • HVACNUTHVACNUT Member Posts: 3,350
    edited June 27
    A/C typically powers the Hi speed terminal. However, Hi speed on the motor is Black. You're showing Red (Lo speed) in your pic.
    Like the diagram shows:
    Hi- Black
    Med- Blue
    Lo- Red
    Switching the thermostat to "fan on", might energize a different speed.
  • Sergea29Sergea29 Member Posts: 22
    Thanks everyone. Would someone know how the control board knows if it is a call for heat or for cooling. I think the yellow wire from the thermostat is not even connected to the zone board in between the thermostat and the air handler. Fyi the air handler is mostly for a/c, heat is secondary as the main heating is radiant floor heating.

    Thanks again
  • mattmia2mattmia2 Member Posts: 1,297
    Y is cooling, G is fan, W is heat. Typically a t-stat closes Y and G to R on a cooling call. If only G is connected, it will usually produce a low fan call in newer systems, which might be why the wires were reversed.
  • HVACNUTHVACNUT Member Posts: 3,350
    Do you have the manual? Or download it? Comfort- Aire?

    Or if you have a meter, you can check to see which terminal (Hi- Med- Lo) gets 120v on a heat call. Dip switches control the time delay.
  • Sergea29Sergea29 Member Posts: 22
    Thank you. Yes Comfort Air. The manuals i have or found does not mention anything on the fan speeds.

    Serge
  • HVACNUTHVACNUT Member Posts: 3,350
    Fan speed matters for air distribution of course, but in your case it should be set for speed and water temp to best match the BTU's needed to heat the space.
  • Sergea29Sergea29 Member Posts: 22
    Thanks again. As mentioned in an earlier post, it is used only for aux heat main heat is radiant floor heating. Its main function is for A/C and since my vents are in the floor ( because added to old house) I want to make sure for A/C I am using the highest speed.

    Serge
  • Sergea29Sergea29 Member Posts: 22
    I tested the three leads high low medium and getting 120, 70 and 100 respectively with just the call for fan. Same when A/c starts. Since all the lead seem to be outputting what does this mean and what is the impact of the reversed red and black leads.

    Thanks

    Serge
  • mattmia2mattmia2 Member Posts: 1,297
    the terminal on the board with 120v is the one that is active. the voltage you are measuring on the other ones is flowing through or being induced from the motor.
  • ratioratio Member Posts: 2,428
    Pull the three fan leads off the terminals & turn the thermostat to each setting to prove which terminals are energized. Turn the condenser off to avoid causing issues due to no airflow across the coil. Plug them back in according to the speed you want, using the table in the schematic to determine low/med/high. A wye cable can be fabricated if you want two functions to have the same speed. Be sure to isolate any unused speed taps. Note that ΔT must be within acceptable range, some taps may not be useful.
  • Sergea29Sergea29 Member Posts: 22
    Thanks all, very helpful information.

    Going back to an earlier post in the thread i mentioned the y wire going to the air handler is not connected to the zone board that is in between my t-stats and the air handler. The y wire from the zone board is going directly to my heat pump and not the air handler. Any ideas why? Should the y wire ve connected to give more speed options say low for fan only, high for a/c and medium for heat.

    Serge
  • HVACNUTHVACNUT Member Posts: 3,350
    edited June 27
    Switch the Black and Red leads. Hi speed terminal on the board to Black, Hi speed fan. Don't worry about the other voltages.

    I don't know why they didn't connect to Y on the board, but it has no effect on fan speed unless your thermostat is capable of setting "fan on" to Med or Lo.
  • mattmia2mattmia2 Member Posts: 1,297
    HVACNUT said:

    Switch the Black and Red leads. Hi speed terminal on the board to Black, Hi speed fan. Don't worry about the other voltages.

    but if the thermostat is connected to g instead of y, isn't the thermostat making a fan call instead of a cool call?
  • ratioratio Member Posts: 2,428
    mattmia2 said:

    but if the thermostat is connected to g instead of y, isn't the thermostat making a fan call instead of a cool call?

    Yes. I would extend it to the air handler & land it appropriately. It appears that the control board has a freezestat that will shut off the compressor if the coil starts to freeze. This is a nice feature that I personally would use. It entails landing the Y call from the thermostat & the compressor command on two separate terminals

    I would imagine that the board will give different fan speeds for the three different calls, but I can't be sure without a manual. You can relabel the three fan speed taps with what energizes them, that would make setting it up a little easier.

  • Sergea29Sergea29 Member Posts: 22
    Thanks Ratio.

    I connected the thermostat y to the air handler and it did not seem to change the speed, the y was sending a 24v. So would it be normal that the fan is only controlled by g and the added y call does not change anything... It is pretty hot so i won't test the call for heat from my heatpump right now to see what call for speed it gets.
    As for the freezestat, the y going to the compressor ( i am the assuming heatpump) is cut before leaving the air handler and instead the y to the heatpump is coming directly from the zone control between my thermostat and air handler. Could the y to the heatpump come from the air handler instead of the zone control.

    FYI, the original installers had a lot of problems setting my system up, with many issues after the install, I had some problems with the a/c not working and may explain the unconnected y. Anyways this is the reason i am trying to understand how it works.

    Thanks for all the help everyone,

    Serge
  • ratioratio Member Posts: 2,428
    Ok, I found an IOM for that unit here. It says on page 3 (page 4 of the pdf) section G. that Terminal number 4 on the fan relay (FR) is the cooling blower speed and terminal number 6 on the fan relay (FR) is the heating blower speed.

    That doesn't appear to match the picture of the control board.

    If you turn off the outdoor unit at it's disconnect, you can run the air handler in heat or cool without any issues. I think you're going to have to do that to figure out which terminal is energized for the various modes, unless there does happen to be a fan relay with terminals 4 & 6 on it.

  • HVACNUTHVACNUT Member Posts: 3,350
    > @ratio said:
    > Ok, I found an IOM for that unit here. It says on page 3 (page 4 of the pdf) section G. that Terminal number 4 on the fan relay (FR) is the cooling blower speed and terminal number 6 on the fan relay (FR) is the heating blower speed.
    >
    > That doesn't appear to match the picture of the control board.
    >
    >
    >
    > If you turn off the outdoor unit at it's disconnect, you can run the air handler in heat or cool without any issues. I think you're going to have to do that to figure out which terminal is energized for the various modes, unless there does happen to be a fan relay with terminals 4 & 6 on it.



    I dont think that's the same board.

    @Sergea29, we now know the black motor lead is Hi speed and it connects to Hi on the board for A/C.

    You mentioned heat pump but that unit has an integral hydro coil, so I'm confused.

    Is this secondary heat source staged through the thermostat?

    I'm not familiar with that zone board. Damper system on that air handler?

    Bottom line, what are we trying to figure out now? You want to run Med or Low on heat mode?

    The board in your air handler seems OEM and specific to that model. I cant find it on the ICM website. I noticed a Universal board shows AQ (Aquastat) can control the fan on a heat demand but it doesn't mention speed, and shows only one motor hot lead.
    With AQ "ON", the fan will energize after the hydro coil aquastat closes, and sends 24v to AQ on the board. Whether that controls a different fan speed, I have know idea. But I'd like to find out. With AQ "OFF", the fan is controlled by the thermostat in heat mode.

    A relay can be added to run a different fan speed for heat.
  • Sergea29Sergea29 Member Posts: 22
    Thanks. I am actually trying to get fan only at low and a/c at meduim or high. My main heating is radiant floor, the heatpump is only aux heat and yes through the thermostat ( ecobee). The hydro coil i believe is to defreeze my heatpump. I found this which show some more info on my board. The fan and a/c is high dehumid medium and heat low. I was thinking of trying to find a way to use the dehumid the set the speeds i want.
    All the dampers are controlled by the zone board, Carrier.

    Serge
  • ratioratio Member Posts: 2,428
    Looks like you'll need to do some relay magic to get a low speed fan-only G call out of the unit, as it said that G is high speed. Connect a spdt relay coil to the Y call, take the HI terminal from the air handler to the common of the relay, the low speed tap to the NC, & the high speed tap to the NO terminal. G will run the fan in low, Y will run the fan in high.

    Verify the rating of the relay you're using.

  • Sergea29Sergea29 Member Posts: 22
    Thanks. So no hope simply using the dehumid call?

    What rating should i look for in the relay?

    Serge
  • ratioratio Member Posts: 2,428
    The unit energized the 'HI' terminal for a Y (cooling) or G (fan) call, the 'MED' terminal for a dehum call, & the 'LO' terminal for heat. You want the fan on high speed for cooling & low speed for fan-only, right? How does it determine it needs to run in dehum? If there's a separate dehum terminal, try landing the fan call (usually green wire) on it & moving the low speed tap to the 'MED' terminal. Run it in all modes (including fan on [not in auto] with a cooling call) to make sure we didn't make it worse.

    it's not clear if you use this unit for heat at all, if so, you may want to make a wye cable to run low speed for both dehum & heat call.

  • Sergea29Sergea29 Member Posts: 22
    Thanks. I am away a few days and will update once i do the tests.

    Serge
  • ratioratio Member Posts: 2,428
    Oh—forgot about the relay. If needed, you'll want a 24 VAC coil, single pole double throw (AKA form C), rated for at least the horsepower of the motor & twice that would be fine.
  • Sergea29Sergea29 Member Posts: 22
    Ok so tried the g call connected to the dehum terminal and nothing happens. I assume g terminal needs to be called as well. So using dehum won't work. The relay seems to be the only viable solution.
    This is a bigger job so may not happen soon. I will update if and when it is done.

    Thanks again everyone, greatly appreciated.

    Serge
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