Furnace fan center troubleshoot

[@hollywd269]

Thank you so much for your videos. Your content saved me a lot of $$$ by watching and troubleshooting my own system as I'm just a regular home owner. I was able to follow your video and determine my transformer was bad on a 1992 lennox and the part came as one unit with the resistor and transformer. And this was my fix. Thank goodness for you with content on older units... my house is warm and comfortable again!👍

[@grayfurnaceman]

Its good to be warm GFM

[@jackmcdonald7391]

This technology looks so old.I love it.Im an hvac tech and i just got done diagnosing one of these for the first time.Good stuff

[@bassman8095]

I learn sooooo much from your training videos, they fill in the blanks between learning theory and actual in the field hands on training. thanks for sharing

[@grayfurnaceman]

Thanks for the support GFM

[@remscurvo]

Another useful video; clear and to the point with several possible faults with solutions presented. Thanks.

[@ahmedfaraz11]

Thanks you so much for the video, it was really helpful in checking my fan relay.

[@zachosborne6577]

Replaced one of these yesterday and it tried to throw me for a loop. Thanks for clarifying some things

[@mercexpable]

Your videos are very helpful and informative. Helps me the DIYer understand. Thanks!

[@grayfurnaceman]

Merry Christmas GFM

[@mercexpable]

Merry Christmas GFM!

[@1942nn]

EXCELLENT explanations on fan control. Understanding how fan control work is the base for troubleshooting fan related issues. I have learned quite a bit about the wires at the thermostat (and at the furnace) and that allow me to understand the explanations in this video 100%. I have even played with the jumpers (R to G, and R to W) and get expected results before watching this video. The reason I watched because when I turn ON the fan at the thermostat (same as jumper from R to G) the fan runs at high speed. When fan is set to AUTO, and heat is ON, the fan is not working !!! This tells me that the G at this time has 0 volts (by thermostat design, verified here and verified on simple bench test). So my fan problem is somewhere in the low speed control of the fan. That is my conclusion, please correct me if I am wrong.

[@tecenter]

Dear GFM, After replacing the fan motor last week in my antique 1960 ? input 105k btu (like the pane antique) or maybe 1970? GE Model 21LU10502 M1 serial 555947 029 while temps outside were below freezing, I'm now interested in untangling the birds nest of wiring in the fan center control box, so as an inexperienced handyman I can make a crude wiring diagram of the simple furnace wiring and color code, as well as oem transformer and relay part numbers. This video gave me the name I was looking for concerning my still in service antique that I've been the sole maintainer for the last 23 years. OMG it's still chugging away thanks in no small part to your tubes, especially the ones on the old antiques. Billy in Rochester NY

[@davntelisha19]

Thank you fellow everything you did i am getting power from my fan so thermostat but out honeywell

[@ATeamAdam]

Nice video gray. I always appreciate how you break things down. Still waiting on a video for three wire heat thermostat.

[@grayfurnaceman]

Its coming. GFM

[@robertweeks1171]

Nice Video. Great troubleshooting tips.

[@aaronfelix1252]

I have an issue with the heat and condenser fan running at the same time.

[@kevinkevin9448]

Best channel

[@LubaLuba1]

Under limiter wheel switch there looks like a rollout switch I have one not so close it's on housing of the chamber frame could this keep my fan running continuously without turning off?

[@rastagrastag7784]

So, after all, that, if you're not getting your fan to come on after the furnace has heated up, then all signs point to the limit control?

[@michaelpriest]

I need to know where the colored wires from the thermostat hook up to the fan control center, much like the one in this video,, thanks so much

[@grayfurnaceman]

Michael Priest I did a video on color codes that may help: kzbin.info/www/bejne/o328ko17bsepZ8U If not, let me know and I will try to explain. Hope this helps. GFM

[@jefferyalsept9386]

Coleman oil burner model msr-c # the blue and white that come from the fan blower were do they go

[@AlejandroMorales-mf3zm]

How it call the tablet board

[@tptm100]

How many volts is that middle crew terminal with the green wire, are there supposed to be wire from Y and W to Fan Motor?

[@grayfurnaceman]

The green should have no voltage if the fan switch is not on. The Y is to energize cooling and W is to energize heat. GFM

[@grapegod6646]

my furnace turns on ,heats but wont shut off when the room temp hits desired temp, the heat shuts off but blower still runs, if you call for more heat the burner engages but blower wont shut down when it comes to temp? thanks

[@grayfurnaceman]

I would be looking at the fan switch. Your furnace probably has a heat operated fan switch that can sometimes stick. GFM

[@gmoneyga84]

My blower fan will cycle back on for about 1min. About 5 min. AFTER the thermostat is satisfied and blower shuts off. it just started doing this.. any thoughts would be much appreciated , thank you

[@richarddiaz1951]

Did you find out what it was? Mine is doing the same thing

[@plumbingheatingairconditio4531]

love you videos. i have a question ?why would the fan come on when you give 240 on a electric furnace. when i pull out the relay the fan stops. the fan does the same thing when i have changed the fan switch, and the relay.

[@grayfurnaceman]

I would be looking at the low voltage controls. Try removing the G terminal from the terminal board. If it stops, the problem is in the G circuit. Shorted G wire? GFM

[@plumbingheatingairconditio4531]

@@grayfurnaceman will do and keep you posted thanks

[@miguelperez1812]

what happens if you jump w-r and the burners don't turn on,.... what would the problem be then ?

[@grayfurnaceman]

There are many possible problems here. First, is there power to the furnace? GFM

[@miguelperez1812]

g-r bypass and yes fan motor stars

[@grayfurnaceman]

Gas, oil or electric? GFM@@miguelperez1812

[@miguelperez1812]

Gas@@grayfurnaceman

[@gerardomireles122]

Thanks again GrayFurnace Cool video very much Let me know if the box The transformer mounted on the Square box is 4x4 or 4" 11" 16" Let me know

[@kevinkevin9448]

Fan keeps running then i move the fan limit control towrds low setting any thoughts ??

[@grayfurnaceman]

The fan switch has probably stuck closed. Means replacement. GFM

[@Aaalllttt123]

Hi, I have a clicking noise coming from the transformer or relay. The fan seems like it tries to cut out for a split second as the speratic clicking is happening. Which do you think this would be, the relay or the transformer? Thanks in advance.

[@grayfurnaceman]

First, I would jumper out from R to G to see if something outside the relay is failing. GFM

[@eman3208]

Thanks grey man....

[@grayfurnaceman]

Welcome GFM

[@408BayArea]

Can you do some on ductless mini splits?great video

[@grayfurnaceman]

As my equipment comes from the junk pile, I will have to wait for one to be available. I will then definitely do as series on it. GFM

[@bbal78]

i just noticed that we jump from W to R at 4:59 , i have read that it is unsafe to bypass the thermostat in heat mode

[@grayfurnaceman]

This video is about troubleshoot. We often jumper parts to decide what the problem is. Of course we would not leave a jumper in. That would allow the structure to overheat. The only exception I can think of is if you have control system that is designed to work as a unit between the thermostat and the air handler. Thanks for the thoughts. GFM

[@danik1234100]

Jumped w to r but burner doesn't come on any idea what do do next

[@christopherdixon5373]

I opened furnace and blower started again after 2 day fail now my blower won't turn on. the system runs a day or so then fan stops again? will a fan limit switch on an old sears furnace work sometimes then not work? I turned off power and the continuity tested ok when I rotated the disk?

[@grayfurnaceman]

+Christopher Dixon Anything that works may not work. lol Sounds like the the fan switch is sticking off. I would replace the switch. GFM

[@ramon59MCchevy]

I have a buzzing transformer on the fan center any idea what could be happening? everything is running fine. It is a brand new fan center as well.

[@grayfurnaceman]

Some of them just buzz. You can replace again. GFM

[@ramon59MCchevy]

Thank you

[@stateraider236]

why would a fan control center be getting hot in ac mode only i have ohmed all low voltage and high voltage on cooling circuit i also pulled amp draws on blower motor in both heat and cooling speeds both in range cap is also good

[@grayfurnaceman]

They sometimes get pretty warm under normal operation. You can check amp draw of the control circuit. It should draw no mare than 1.6 amps. GFM

[@stephenpistoia1227]

Hi I have same unit in your video. The heater won’t shut off after reaching temp at thermostat. I’m only getting 14v at W on transformer. Is it possible the relay stuck on? Any feed back would help thanks

[@grayfurnaceman]

Does the burner stay on or just the fan? GFM

[@joec369]

My fan will not come on for heat or ac. I jump G to R. And it turns on fine. Any suggestions? Oil heat, I’m in crawl space now lol.

[@timbowker5601]

my fan won't come on my ruud forced are gas furnace so it won't light unless I spin it with a pencil to get it going.then it will run.but after it shuts down I have to do it again.can it be oiled?

[@grayfurnaceman]

+Tim Bowker If it moves easily, there is no problem with the bearings. However, if it is a PSC motor, it probably has a failed capacitor. Hope this helps. GFM

[@stevegalvan6397]

I have a delemna sir...when I set thermostat, blower turns on and heat ignites but when temperature reaches settings on thermostat, blower and heater will not shut off...fernace stays running. ..what say you will? thermostat issue? relay?...I'm at a loss

[@grayfurnaceman]

First, disconnect thermostat with the furnace running with the thermostat set at its lowest setting at the thermostat. If it stops, the thermostat is the problem. If not disconnect W at the furnace. If it shuts off, you have a wiring problem. If not, it is in the furnace itself. GFM

[@stevegalvan6397]

thank you. ..I'll try that...I appreciate the input

[@RobHVAC]

Nice video.

[@brettpotes5466]

Could be transformer converts from 120 to 24 bolts I believe fan runs on 24 volt this video will show how to test some what

[@grayfurnaceman]

Your fan is controlled by 24 volt controls, but the fan operates on 120 volts. GFM

[@SuperSincere1]

What if you were to jump from r to g and can get the fan on but when you jump from r to w nothing happens?

[@grayfurnaceman]

You know there is power to the furnace and the fan works. Now you need to find out if there is power to the furnace controls. GFM

[@SuperSincere1]

@@grayfurnaceman I verified 24 volts to R with meter. Hence I was able to bring on fan when I jumpered R to G

[@grayfurnaceman]

@@SuperSincere1 Next you need to verify 24 volts to W at the furnace on a call for heat. GFM

[@andystitt3887]

Is the blower supposed to come on before the burner?

[@grayfurnaceman]

Generally, no. If the fan relay is energized in heat, the fan will come on first. But that is not how furnaces generally operate. GFM

[@winkhvac62]

Great video

[@geojor]

good video, thank you...

[@jimbola77]

thanks GFM!!!!

[@davidpope8278]

I jumped g to r fan comes on jumped g to w burner comes on changed thermostat still not coming on in heat mode when I touch g to r at thermostat no fan any ideas could it be my fan limit switch

[@grayfurnaceman]

If you jump G to R at the furnace and the fan comes on, then jump G to R at the thermostat and nothing, you have an open in the thermostat wire between the thermostat and the furnace. GFM

[@davidpope8278]

grayfurnaceman before I changed thermostat fan worked in fan on mode but not in auto after I replaced Tstat no fan in on or auto I was thinking new Tstat might be defective but slim chance with old stat working fan in on mode do you still think open wire or any other thoughts and thank you for replying and your vids these old units dont talk back like new control boards lol

[@grayfurnaceman]

@@davidpope8278 To double check, you can remove the thermostat wires from the thermostat and jumper R to G, fan, R to W heat, R to Y, cooling. Then do the same at the furnace. GFM

[@davidpope8278]

grayfurnaceman Did that this morning of course u were right on point GFM wire was open/broken had to improvise found an old twisted pair analog phone wire in crawl space tested it used ohms law to calculate power draw only 5ft run ran it now good to go. You are a HVAC/Furnace repair God!

[@grayfurnaceman]

@@davidpope8278 Glad you got it going. GFM

[@joshkisul1932]

Nice video I know it's old so dont know if I'll get a response. I have a williamson gas forced furnace. I had a black out and when the power came back on my furnace doesnt work. It's a oldie lol I have a 10amp fuse right by the switch for on/off. I tested fuse thays good but I dont have any power at the transformer coming out. Are they hard to change?

[@grayfurnaceman]

They are not generally hard to replace. This video may help: kzbin.info/www/bejne/imXJiJtml9GSl7c GFM

[@1986pistolpete]

I was working on this furnace and the rollout switch opens with no actual rollout...I believe the metal housing heating up causes it..what's your thoughts?

[@grayfurnaceman]

Are you sure it is not rolling out? You might try replacing it and see if it continues. Hope this helps. GFM

[@AZDESERT2024]

What should happen when you jump R-G ?

[@grayfurnaceman]

The fan relay will energize and turn on the fan. GFM

[@miketaylor1356]

My furnace won't turn on it looks like the one in the video

[@andyc2730]

you should try to watch this video yourself. Terrible !