Honeywell International ST9120U1011 Fan Timer Control

Have an older furnace and when I had a no heat situation the HVAC companies all said I needed to replace my fan control unit because the high voltage relay on the board that turns on the fan was fried. Quotes were $800 and up. I work IT problems at my company before we pay to have the expensive techs come in. I thought hmmmmm, this sounds suspiciously expensive considering how cheap electronics are these days. Did my Google, YouTube and Amazon-fu like a good girl, while using my fireplaces to keep my house warm. Lots of wood laying around from storm cleanups and it was nice to get it cleared off the property.Anyway, found out that the reason the fan control relay fried was that the actual fan motor that blows air into the house was going bad, pulling too much electricity through it as it degraded and resistance skyrocketed and my power bill started creeping up from a normal heating season.Told the company techs that they were going to just fry a new board and the fan was the culprit. They replied that they always try a board first and then move onto the fan since it is labor intensive to remove and replace and instead recommend a complete new furnace (Quotes were 4 thousand dollars to 6 thousand dollars because it was an 'emergency no heat job') so that they can fully warranty the work. Again sounded fishy. Researched removing the fan motor and it is stupid easy. Take out two little screws and the whole fan assembly slides out on rails built into the furnace. Got the part number off the fan and ordered one up with next day air shipping after the one on here ended up not being in stock when the company said it was and had to cancel the order here.So just yesterday I installed the new electric motor that was $275, a new start run capacitor (cheap and all installers recommend using a new capacitor with a new motor) for $10 and the fan control board here for $90 and with a simple follow the manual to adapt the wiring to the new style board, voila I have heat and the motor is rated at a 40+ year lifespan at normal heat and ac seasonal usage. Mentioned what I did on the subs I frequent on reddit.com and they all said, 'Yup you basically got a new furnace and it is what we HVAC techs do with our own home, no need to change out all the big sheet metal parts when it is just the fan motor, board and cap that you needed. The burner control unit when it goes is cheap and easy to change out too."I feel so relieved that I now know how to work on a furnace and how simple and cheap they are to repair compared to the high pressure sales tactics the HVAC companies use to get you agree to all new everything for the price of a decent used car. Nope, I will do it myself for under $500 please and thank you!

My upstairs HVAC unit stop forcing air through out the floor plan. After conducting my own diagnostics using YouTube University, I was able to rule out the blower fan as being the culprit. The original circuit board was not sending voltage out of the cool or heat terminals. The original board was a Honeywell model number ST9120C 2028. The new board from amazon is compatible with this board along with other 9120 model boards. Upon unpacking the new board, I noticed a few differences on the board's pin layout. The native board S1 and S2 translated to the new board L1 and L2. The old D1 terminal which was the inducer terminal, translated to the new board IND terminal. The instructions/scehmatics was easy to follow. Be sure th label your old leads/wire before removal. I also took advantage of cleaning the blower fan and housing unit, which greatly increase air flow. Note the new circuit has a troubleshooting LED which flashes if there is a problem. The number flashes corresponds to a fix action in the manual. Upon removal of the native board, I inspected the components and noticed the back of the board was arced. The arced location was under one of the relays. This arched relay terminal was the cause of no power being sent to the blower mower. I also replaced the capacitor since i pulled the housing. Pulling the housing to replace the board was not required, but it was a good opportunity to conduct preventative maintenance. After replacing the board and reinstalling the blower assembly the unit fired right up. Thank you Amazon and Honeywell. The card also retails for $190 at appliance shops. Amazon sold it for $95. This repair could have easily been over $500. I will provide an update in the future.Happy Customer

I have installed the new board on Consolidated Industries furnace MBA 080 NH3R from 1996. My furnace stopped working and failed to start. It was doing nothing to start, no inducer motor sound, no igniting. When I tried to force the blower fan ON manually on the thermostat it was making repeated click sound as a relay clicks. First I have suspected the blower motor. But I connected the blower motor wire directly to the 120V and the motor was running. After that I decided to replace the old ST9141 control board with the new universal one ST9120U1011. I spent almost 3 hours to replace the boards got it working. I want to share some issues for my particular board. Some old wires appeared to be short and needed to be extended. If you don't want to cut the old wires have prepared couple feet of new wire and several pairs of spade terminal with male-female options to extend the wires. And there was another issue that some old spades were too small to mount on the new board blade terminals. I have to cut them and replace with new spade terminals. I have not touched any dip switch settings, left as they were on the board. As for many people here it was my lucky day when I got this working because I was about to replace the whole old furnace with the new one.

Took some time to figure out what the coordinating connections were. The directions were not totally clear.One installed, it worked as expected. Saved us about $700 by installing it ourselves.