Model serial number of your A/C system?
Who installed the system? The blower Control board needs needs to be set up and not just from the Vision Pro IAQ.
Did you purchase a system that can control humidity?

There should be install manuals for the Air Handler and visionpro IAQ.

O/D unit 4A7B4036E1000AA
Air Handler 4TEE3F65B1000AA
A/C unit installed by one contractor and thermostat installed by another. Do not have whole house dehumidifier but system should control dehumidification by fan speed and over cooling. DIP switches have been set on control board of air handler. I did not select the enhanced settings because I wanted the IAQ stat to control the process when needed. I have the manuals you referance plus some I downloaded from AS/Trane.

Mine will be installed in our new house, which isn't finished yet, so I don't have it to play with. To familiarize myself with the 'stat ahead of time, I have downloaded four different manuals for it, User, Install, Tech Data, and Equipment Interface Module. It looks like you need all four to figure this thing out.

The EIM manual shows a connection for a variable speed blower. The connection is via a normally open or normally closed contact. That part seems to be selected in the setup menu, although I don't recall seeing it there.

What isn't clear at all to me yet is how you program the 'stat to dehumidify via the VS blower and not by overcooling. 'Tis a complicated beast for sure.

creek_side
When I read the manuals you make referance to, I came away thinking that the stat makes that decision for you. For example if the difference between the set point humidity and the actual humidity is too great, over cooling is the way it will go. If they're close, slowing the airflow will be the process. Note that the efficiency of the system decreases when you slow the air flow. Usually still in your favor, costwise, when compared to running fullbore.

I think the first thing to do is to find out if it is even wired correctly. Are you comfortable with wiring and the use of a multimeter? If you are, take a look at the EIM and see if anything is connected to terminals DHM1 and DHM2.

If there is, measure the 24 VAC voltage across the terminals. It should change when the house humidity crosses the 'stat's humidity set point. If it does, and there is no change in the blower speed, the NC/NO relay setting (wherever it is) may be incorrect.

If there are no connections to DHM1 and DHM2, it isn't wired for VS blower humidity control.

You should probably read through your VS AH installation manual before you do any of this to see what it expects and note any cautions that may be given.

dip switch for best humidity control with your condenser
on-on-off-on-off-off-on-on > 350cfm per ton
or normal mode:
on-on-off-off-off-off-on-on > 400cfm per ton

wiring:
Remove Jumper from DHM 1 / DHM 2
Jumper EIM R to DHM 1 on EIM(Equipment Interface Module)
wire Air Handler BK to DHM 2 on EIM

in program install setting
0370 set to 1
0379 set to 1

Anyways I'm so glad I mostly deal with Bryant Evolution, The Trane/AS with all the little dip switches and set this and that gives me a headache!

but there you go

classicdave
Thanks for the help.My DIP Sw are set as you have them for normal mode-400cfm. 0370 and 0379 are set as you show them. My question-in the service facts packed inside the air handler, the wiring diagram shows a jumper from R to BK. Should that be removed before I run the line from BK to DHM2? Also, do you know if AS/Trane publishes a theory of operation for the fan control board in my air handler or even a schematic of the board? My background is in electronics and I like to have an understanding of the circuitry involved.

Yes remove the R to BK jumper
On a call for dehumidification, the contacts will open and kill power to BK.

And no I haven't found any manufacture to list the theory of operation.
These humidification Air Handlers or furnaces are driven by ECM motors that are set up so each manufacture creates there own fan controls for them and they don't list any information.

Dave, the manual shows either a NC or NO set of contacts between DHM 1 and DHM 2. That is supposed to be selectable somewhere, but I can't find it in the manuals. Do you know how that selection is made?

Setting 379 to 1 makes it NC
setting it to 3(whole House Dehumidifier) sets it to NO

Thank you. We are getting Rheem equipment, which seems to use the opposite logic from the rest of the industry to control the blower speed.

classicdave
I'd like to pick your brain again, if you don't mind. What is the purpose of the Ylo terminal as opposed to BK. I was under the impression that the Ylo was the fan low speed terminal.

Normally a Ylo and O is jumpered and BK and R are Jumpered
When using the Ylo terminal.
A signal to Ylo creates 50% CFM from the blower, a signal to Ylo and Y the blower will run at 100% This would be used in XL19i or XL20i with 2 compressors. Say 4 ton XL20i system, has 2 compressors, a 4 ton and 2 ton compressor.
In high stage blower runs at 100% with 4 ton compressor,
low stage runs 2 ton compressor 50% of blower cfm capacity.

BK and R with jumper removed capacity drops from High 80% and Low 40%

I won't kid, it can get so mixed up with do this don't do that, that a normal install crew that only installs one of these a month may get confused and lost. This is why Trane has their communication controller XL900 with Comfort Link II and with that there is where my knowledge ends because I've spent the last 3 yrs with the Bryant Evolution and Carrier Infinity communication systems.

classicdave
Thank you for all the help you gave me in getting my IAQ wired properly. I still don't know if it's working as it should but at least it didn't blow up after the rewiring.