Indiana FHP AP049 - auxiliary heat not operating correctly.

Discussion in 'Maintenance and Troubleshooting' started by mgherter, Jan 14, 2015.

  1. mgherter

    mgherter Proud Noob

    Hi folks, my first post here.

    This is our first winter in this house. The unit was installed in July 2012 but a company that doesn't do much with geos, but the previous owner really wanted air conditioning and didn't want to wait.

    During this recent cold snap we have had, the unit has had trouble heating the house comfortably. For instance it simply can't get above 61 or so inside when it gets below 0 outside. We set it at 65...because I am cheap...and it just runs, so I have been setting it lower and lower. I've done a little research and have the manual for the unit. My opinion is that the aux heat will not come on, even when the thermostat is calling for it.

    There's a control board in the geo with LEDs. Even if the thermostat calls for aux, the aux LED does not light up, and the air temp coming out of the vents does not increase. Y1 and Y2 light up when the unit comes on, and the fan is putting out plenty of air (there's a blinking LED that indicated 1700 cfm). Even with Y1 and Y2 on, it's not maintaining a comfortable temperature, but that could be because it's been sub zero, even for the high, over the last week.

    So - what I want to do, but can't figure out how to, is test the aux heat strips directly to see if they'll come on (if that's the the right thing to do). The t-stat seems to be wired correctly. I have pics of the board and wiring that I can upload if it's helpful. Don't know if it's even possible to trouble-shoot this way; the manual is not much help in this regard. I was hoping there would be a "functions test" or something I could run.

    One thing I should have done was test the EM heat. Will do that later.
  2. mgherter

    mgherter Proud Noob

    New info:

    EM heat works. I can spell the ozone, electric heat smell. fan with EM heat. Which leads me to suspect wiring.

    Wiring is funny. There are 8 terminals on the board in the furnace: Y1, Y2, G, C, O, Rc, W1 and W2/E. I know what all those are supposed to do. The t-stat does not have a W1 or W2 terminal, just a single Aux/E terminal. There is 8-strand wire running, but no place to connect it on the t-stat.

    Doesn't it make sense to have a t-stat that can connect to the board one-to-one? I could get a different t-stat and test it out, there appear to be many models out there that have explicit connections for W1 and W2. Bad idea, good idea? There is just no competent service people in the area, so I am trying to do what I can before I call someone. I've had people out here before that have said all is's definitely not.
  3. TheDude

    TheDude The Dude Abides

    Yes, pics would help.

    If your thermostat can call for stage 1 and 2 and Aux than it should be good.

    There is definitely a problem if the elec heat strips are on without the fan.

    Where is the Aux wire from the thermostat connected?
  4. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    Your thermostat typically has a setting that turns on the electric heat and fan by tstat or if integrated with unit, by the HVAC unit. If it was installed completely separate, then the heat pump doesn't recognize it exists so won't turn on the fan, even if the thermostat is turning on the auxiliary. Find that setting and make sure the thermostat turns on the fan with an auxiliary call.
  5. mgherter

    mgherter Proud Noob

    Aux wire from t-stat goes to the W1. There's a jumper from W1 to W2/E. It's messy, the brown from the t-stat gets spliced to the white right by the board (it has a voltage, the splice is good). So it's Brown/t-stat connected to white/main board. And then they used a bit of the brown wire as a the jumper. Don't ask me, I wasn't there.
    [​IMG] ---> LED bank while t-stat is calling for AUX.
    [​IMG] ----> Terminals on geo main board. There is a black common, just can't see it.
    [​IMG] -----> T-stat wiring.
  6. mgherter

    mgherter Proud Noob

    OK, I will go through the setup on the t-stat. Have not done that.
  7. TheDude

    TheDude The Dude Abides

    I can't see the photos.

    I am not sure I follow exactly how it is wired, but it doesn't sound right
  8. mgherter

    mgherter Proud Noob

    Sorry about the images...I had to right-click and open them in a new tab. I think because I am new they are balking at letting me post links.

    Anyway I can try to clarify...

    T-stat-----Geo (wire color)

    Y-----Y1 (yellow)
    Y2-----Y2 (blue)
    G-----G (green)
    O/B-----O (orange)
    C-----C1 (black)
    Rc-----Rc (red)
    Aux/E-----W1, with a jumper to W2.
    Control Board LEDs.JPG Control Board Wiring.JPG T-stat Wiring.JPG
    It looks like it let me upload the actual photos. Thanks for working with me.
  9. TheDude

    TheDude The Dude Abides

    While its not the cleanest job, it appears to be all there.

    So I am assuming that the brown wire wasn't long enough to make it to the board, so they spliced it?

    You said that the splice was good and the wire has voltage. How are you measuring that?

    If you have a voltage meter AND are comfortable using it in a live unit with dangerous voltage you can test a few terminals to confirm or rule out a problem with the wiring.

    It looks like there is a white wire in the wall by the thermostat, does that fall short also?

    Could also be a setting on the thermostat as Chris noted
  10. mgherter

    mgherter Proud Noob

    I have no idea why they did what they did with the brown wire. It doesn't make sense to me either. It's plenty long.

    Measuring between the W1 and the common when aux is commanded. Wrong?

    I've been up to my elbows in this thing for two days now, a couple more tests with a multimeter can't hurt. The model is FHP AP049. The manual is here, if looking at the board schematic helps.

    The white wire is in the wall, just not being used. There's no place for it on the t-stat, at least by itself.

    Will check the t-stat settings tonight when I get home.
  11. TheDude

    TheDude The Dude Abides

    Having an extra wire is good.

    I would start checking across C and G first (with the fan on) than C and Y1 (with the heat on) that will establish what the proper voltage should be should be arould 24v +/-

    Then check C and W1 (with aux on)

    Is there a jumper on the thermostat between Rc and R? Some thermostats need that.

    You might also try moving the Red wire from Rc to R
    mgherter likes this.
  12. mgherter

    mgherter Proud Noob

    Yeah there is a jumper. From what I am reading in the manual, it's supposed to be there unless there are some pretty specialized circumstances. Will check those voltages out. Post more tomorrow, thanks again.
  13. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Off the Heat pump:

    R=red= hot side of control voltage transformer. 24 vac +/-.

    B/C= blue= return to the transformer to complete the circle. Most times this is also a chassis ground, like a car.

    G= input voltage to turn on the fan/blower. Speed may depend on other inputs to the terminal block.

    O/B= input to the reversing valve. Most modern units fail in heating mode. to cool one needs power to O. O= orange.

    Y = yellow= start the compressor. Normally in stage 1. The compressor is started in heating and cooling. The O/B terminal chooses the mode of operation.

    Y2=What ever color is left in a bundle of wires.= second stage compressor or number 2 compressor.

    W/W1= First stage heat.= This depends, read the book. It can be the aux heat. It can turn off the compressor. Read the book.

    W/E= read the book. Usually shuts down the compressor, runs fan on high, and has electric strip heater on. Read the book.

    W3= Third stage heat. Read the book for the heat pump and the thermostat.

    At the thermostat. Who knows? Most of the high end thermostats have programmable variables. The programming is addressed in the installer section and usually not able to be messed with by the customer on the normal interface. Most times. I will know more about that after our call tomorrow.

  14. mgherter

    mgherter Proud Noob

    I get 24ish V across C and G, C and Y1 and C and Y2 when it's on. Nada across W1. Again, I think the LED bank is supposed to light up when it reads that voltage, so I'm not surprised.

    Did a test from the installer settings at the t-stat and it does NOT turn on AUX or emergency heat from there. There's one menu to turn on/off the emergency heat with the fan (it's explicit in saying that emergency heat should come on WITH the fan). I get the emergency heat (the LEDs for W1 and E light up on the board) but no fan. Y1 and Y2 also go off, during emergency heat, which makes sense, because E heat is supposed to operate without the compressor running. Per the manual, W1 or Aux heat is supposed to operate in conjunction with Y1, Y2 and the fan.

    To me, that seems like more evidence it's a wiring problem. Something somewhere is getting confused when aux/E is commanded from the t-stat, but I could be just confirming my own bias. Could I have a fuse or something else out between the transformer and the heat strips? I know what the heat strips are supposed to look like but I can't say that I could point out where they actually are. In the supply air stream, after the blower, I would guess. But when I get down there with a flashlight I don't see 3 big coils.
  15. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    Was this electric plenum heater a separate installation? Is it built in to the unit or separate from it? I could wade through the above, but I haven't.

    Iff separate, the 24V W wiring call needs to go to the plenum heater (likely through a 24V transformer). It does nothing if it is wired to the heat pump board (unless it is split there to the plenum heater as well). And the fan call (G) goes to the heat pump board.
  16. mgherter

    mgherter Proud Noob

    It's in the unit, integrated. It's an FHP (Bosch) Aquarius ii, AP049, if that helps. A 3H/2C, with the 3rd stage obviously being the backup coils.
  17. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Do you have an R/H terminal on the tstat?
  18. mgherter

    mgherter Proud Noob

    No Rh, just an Rc jumpered to R.
  19. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Then R is RH and the jumper takes care of the possibility of no power to the heating portion of the thermostat. I do not see the jumper in the photo.
  20. Bergy

    Bergy Member Industry Professional Forum Leader

    What's the model number of the stat?

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