ICC-500T trouble figuring out how to use it for CO2 exhaust (plug no#2)

Hello All,
I need help desperately, I purchased this unit to keep the CO2 levels down in my wifes grow tent for mushrooms. I thought this would be simple to set up but i think the only simple thing is me!
I have the perimeters set in it. It shows what the CO2 level is. It shows what level i want it to stay at or below. It just does not turn on the fan to exhaust CO2 out of grow tent. Yes i have fan plugged into No#2. If i go down and look at it and see that the CO2 level is over the set level i will need to tap the “set” button 2Xs and fan will run. It will take it down to setting and turn off when it is reached. It just does not turn it on when it goes over? I know its me and not unit i just dont know how to set this. Please dont tell me to read page X because i have read them all many times i just dont understand it. I dont want to throw this unit away and purchase something dumed down for me. I would rather find someone who can help me… So can any of you help me??.. Please…

Could you provide the CO2 range you want to maintain, the current ICC-500T readings and settings?

I’m trying to keep it under 900 for mushrooms. The issue is I do not know how to get it to turn on automatically… I do not need an alarm set in it. I just want it to turn on when i hit my settings and turn off when it goes under my settings… I can only make it happen manually.

Must i set a 24 time clock or something so it knows to work between these times? I thought i read in booklet that you should be able to program settings and it will run on its own.???

The ICC-500T will judge the output switch based on the readings and settings.
Please make sure that you do not need to manually press the button to turn on the fan after it is powered on.
For example, you want the ICC-500T to control the fan to maintain 900ppm - 1000ppm.
Please set CS=900, HD=300, CD=100, AH=5000, AL=300, CA=0, ALM=ON, TR=0
When the CO2 reading reaches or exceeds 1000ppm (CS+CD), ICC-500T will turn on the work2 output. When the reading reaches 900pmm (CS), it will turn off the work2 output.