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Without knowing where George Brown gets its "practice test" from, it's not possible to answer that. Too much studying is never a bad thing. At the end of the day you need to know, and be comfortable with, the codebook.

Hello,
I have an exam next week, and I am preparing for it using a practice test I received from George Brown College. Is this sufficient, or should I practice more questions? If so, where can I find additional resources? Also, could you please let me know what questions you got on the exam?
Thank you!

Looking for opinions from the guys with residential experience.
Changed my furnace 2 or 3 years ago. No problems with the 1997 Lennox. Just old.Put in a Luxaire 2 stage with multi-speed ECM. No issues. Also installed a new 2.5 Ton cased coil with the intention of replacing condensing unit the following spring. Never happened. Hooked the existing 2 ton R22 Keeprite condensing unit back up. Not having any issues.
Thinking now about installing a MITSAIR add on heat pump and connecting to existing coil. MITS says their outdoor unit is compatible with any coil.
What do you guys think? I'm Thinking more about comfort, that I hope will come with inverter duty compressor, than energy savings.
Good idea? Bad idea? If good, do you recommend 2.5 ton to match coil or 2 ton? Kinda always thought existing AC was borderline at best.House is poorly built cookie cutter 1997 1800 sq ft.
I work in commercial/ industrial service. Figure some of you guys know this way better me.
Thanks for input and sorry for long post for short question.

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Thank you, I will look into that

It could be a "chattering" relay on the furnace control board.  If you disconnect the G wire from the furnace does this still happen?

If so I would look at replacing the control board, and explain to the client that likely a dirty filter caused the furnace to cycle on limit and that eventually wore out the old relay due to all the excessive starting and stopping.

Good morning,
I was recently called to diagnose an older Carrier furnace that was short cycling, I found the cause to be a dirty filter and replaced it. I checked everything else and performed maintenance on it and all seemed good to go.
I got a call back and the furnace is working but after it's satisfied on heating, the blower will disengage and immediately turn back on for a second, tested everything I felt might be the problem and all looks good but it's still happening.
Any suggestions on what it might be are appreciated.

thanks!  I will definitely try that.  seems I blew the fuse in the 155MAX and will try again once I source a new one.

Gemini chatbot suggested this is the wiring:

Color Function Terminal #
RED 12V Power 3
ORANGE ON (Control Signal) 2
GREEN LOW (Low Speed) 1
YELLOW HI (High Speed) 6
BLACK COMMON 10

and suggested I jumper red to orange, and then connect acc+ to orange, and ACC- to either green (for low speed) or yellow (for high speed).

I'll report back on which wiring yields the correct result in case others are curious.  I'll make sure I have a few fuses just in case!

I couldn't even see the terminals in the above picture, so thank you for listing them!

I would jumper BLK and RED on the HRV, and if the HRV starts those are the 2 wires to connect to the Ecobee ACC terminals.  The other wires would not be needed.

See the wiring diagram below.  The Ecobee would be considered a toggle switch (dry contacts)

Quote from: Admin on October 21, 2025, 08:27:56 PMYou need to follow the mecanical timer wiring.  See the attached picture.  Install a jumper between ON and RED.  Then wire the Ecobee ACC wires to HI and ON.  The HRV will run in high speed when it's turned on.  You could also use low speed instead.  Just connect the ACC wire to LOW instead of HI.  The Ecobee can only control one speed and not both.

hey there, sorry to jump on a thread that isn't mine but I have the exact same issue and am not sure that the response answers the question.   Like the OP I have a 5 terminal block on the outside of my 155MAX that runs up to a controller with dehumidistat dial next to my thermostat.   the 5 wires are labeled "BLK, RED, ORG, GRN, YLW".  in my existing setup the orange terminal is not connected, the other 4 wires run upstairs.

in your response you have a 10-terminal block which I'm guessing is from newer HRVs?  I definitely don't have that on mine and I'm guessing OP doesn't either as my situation matches his pictures.

Given that there is no ON or HIGH or LOW or any of that.. is there a known solution for which two of those color coded wires from the 155MAX become ACC+ and ACC-?