Replacing 25 year old 1/3 variable speed motor for furnace blower. replacing with same brand (US Motor). three connection points L (low), C (common) and H (high). new motor has modified location of connection points and has colour coded the letters stamped beside the connection points (L-yellow, C white and H black). the colours do not match the wires i have coming from the furnace. The old motor had a yellow wire to the L, a white wire to the C and a red wire to the H. question, do I worry about the colour (in this case connecting red wire to terminal marked with a black H)? or merely follow the letters - connect the wire that was connected to the old H to the new H? Bruce

I've been trying on and off to fix my furnace for the past few weeks. This is only my second winter at this house, but we didn't have this issue last winter. The furnace appears to be ~2015. I'm sorry i don't have the model/pn of my furnace. i can see "M/N:" "P/N", but the rest is cut off for the return inlet, but maybe there's another spot somewhere with it that I haven't found. Also, I replaced the air filter. It was mostly clean, and the change has no affect on the issue.[left] My furnace will turn on and off and heat fine for a few days and then won't turn back on without a hard reset, showing a pressure switch error on PCB (dot dot pause). The recent cold spike increased the frequency at which my furnace won't turn back on, and now instead of a hard reset I have to tap on the 1.5" WC pressure switch coming from the bottom of the inducer next to the inducer condensate drain. You may have guessed it: there is water in this pressure switch's tubing at the fitting on the inducer. [/left] The pressure switch that is not opening after the furnace shuts off due to the water sitting in its tubing just happens to sit at the exact same height on the inducer as the inducer drain. It looks like this pressure switch was intended to stop the furnace if water collects in the inducer. So, i thought maybe the pressure switch is doing its job and there's a water clog. So, I cleaned out the condensate trap, flue condensate tube, inducer condensate tube, and the pressure switch tube. I did find a june bug in the flue condensate tube and some scum in the trap, but cleaning all these has had no affect on the issue. I saw videos of people fixing condensate trap clogs, and they show water pouring out of the condensate tube. So I opened the flue and condensate tubes while the furnace is running, no water comes out. Then the furnace shuts off (b/c i drop the inducer pressure by venting it to atmosphere). I wait a few seconds, and then a slow trickle of water starts coming out of the inducer condensate outlet on the inducer. So i might be heading down a rabbit hole, so please offer other thoughts/suggestions. But right now i'm thinking, what would cause water to only trickle out of the inducer when the inducer is off? My condensate trap has 4 hoses connected to it. One for flue condensate, one for inducer condensate, one outlet, and one 1/4" tube that goes to the top of the inducer. I'd guess the 1/4" inducer tube causes the inducer to pull on the trap, so that the inducer, flue, and trap are all at the same pressure. I remember when i cleaned the trap and condensate tubes, i accidentally left this 1/4" inducer tube off the trap, and i could hear water draining out of the condensate trap. Once i connected this 1/4" inducer tube, i can't hear water draining anymore. Are there some cases where the 1/4" inducer tube is not used on the condensate trap? I did try swapping the pressure switch and it does the same thing. My next step is to check the level of the inducer to make sure its tilted towards the drain, replace the black drain tubing with clear tubing so I can see if water is draining or not, and move this pressure switch so that the tubing goes straight up to the switch, that way its easier for water to leave the tubing. Final possibly unrelated note: I installed Honeywell Humidifier He360a1075 into my furnace a few weeks before problem started (btw this humidifier has been awesome. way less static and dryness in our 2100 ft^2 house). I can confirm water is not leaking into the furnace from the humidifier. The furnace combustion air intake is open to the room (not piped outside), and the furnace is on the first floor just off the kitchen. I thought maybe the humidity of the house is causing more condensate than normal, so I recently turned the humidifier off to see if it's related. unfortunately I only did that last night so i'm not sure if its changed anything. The house is still ~30% RH and i imagine it will take a day or two to drop. That said, i feel like the furnace has an inducer condensate drain that should work well enough to remove any excess moisture from my typically 40% RH, 68°F air. So I suspect this is not the root cause, but may be amplifying the issue. I've read people insulate their flue/vent pipe to reduce condensation, and I've considered that but it sounds like it's more of a bandaid and the inducer/flue condensate drains should be functional. I also am not sure if the flue is clog free or not. The roof is way to steep and icey to get up to check right now, but I can say I see significant flow coming out of it and the furnace isn't having any issue running. it just gets water clogged in the pressure switch and can't restart. The furnace has NOT shut off while running yet. I've actually got it set so high as to run nonstop today because its so cold and I dont want my wife to have to open the furnace to tap the pressure switch while I'm at work. Can I swap the connection of the 1.5" WC pressure switch from the bottom left of the inducer to the top right? That would mean the 1/4" inducer tubing that goes to the condensate drain would connect to the bottom left of the inducer instead of the top right. Would the safety function of the pressure switches be diminished by this change? Part of me wonders if that was the original design and if they got switched during some maintenance.