Furnace_AC How to Troubleshoot The Control Board

WEBVTT
Kind: captions
Language: en

00:00:08.090
hey guys J here with word of advice TV
00:00:10.940 00:00:10.950 in the comment sections for some of my
00:00:13.129 00:00:13.139 a/c fixing videos people have been
00:00:14.749 00:00:14.759 asking me to make a video about how to
00:00:17.390 00:00:17.400 troubleshoot a control board and they're
00:00:19.490 00:00:19.500 actually really not that hard to
00:00:20.750 00:00:20.760 troubleshoot unfortunately to
00:00:23.090 00:00:23.100 troubleshoot a control board you do need
00:00:24.740 00:00:24.750 a meter so if you don't have one you
00:00:26.779 00:00:26.789 might need to get one so take your
00:00:28.490 00:00:28.500 furnace doors off or your air handler
00:00:31.540 00:00:31.550 and most air handlers or apprentices
00:00:35.750 00:00:35.760 will have a control board some of the
00:00:37.310 00:00:37.320 older ones will not for the most part
00:00:40.490 00:00:40.500 there is a control board in every
00:00:42.200 00:00:42.210 furnace typically it'll be located right
00:00:46.490 00:00:46.500 in front of the blower housing where
00:00:48.290 00:00:48.300 your blower motor is once in a while
00:00:50.180 00:00:50.190 it'll be in the upper section too so the
00:00:52.459 00:00:52.469 way it works is you got power coming in
00:00:54.860 00:00:54.870 to the furnace or the air handler right
00:00:57.049 00:00:57.059 here it goes into your power switch so
00:00:59.450 00:00:59.460 if I turn that off it turns everything
00:01:01.010 00:01:01.020 off then you see or the furnace so power
00:01:03.650 00:01:03.660 goes into there the switch is on
00:01:05.719 00:01:05.729 so then power goes into here line
00:01:07.940 00:01:07.950 voltage and then from the junction box
00:01:10.429 00:01:10.439 it goes down and the first place to stop
00:01:13.219 00:01:13.229 set is the door switch as you can see
00:01:15.770 00:01:15.780 mine is taped in order to check voltages
00:01:17.870 00:01:17.880 you do have to have your door switch
00:01:19.580 00:01:19.590 taped most furnaces will have a door
00:01:21.800 00:01:21.810 switch either on the left or right or in
00:01:23.719 00:01:23.729 my case in the middle so tape that or
00:01:25.999 00:01:26.009 put a screw in it so it stays shut and
00:01:27.710 00:01:27.720 then always keep in mind that it is live
00:01:30.289 00:01:30.299 you have 120 volts somewhere there so be
00:01:33.649 00:01:33.659 mindful and don't touch any terminals so
00:01:35.600 00:01:35.610 you don't get shocked so after the power
00:01:37.789 00:01:37.799 goes into the door switch if the door
00:01:39.830 00:01:39.840 switch is closed the powered end goes
00:01:41.840 00:01:41.850 into the control board typically it'll
00:01:44.899 00:01:44.909 be marked line blind voltage goes into
00:01:48.499 00:01:48.509 that terminal so from the door switch it
00:01:50.270 00:01:50.280 goes into there and that's what powers
00:01:51.980 00:01:51.990 up your control board so after power
00:01:54.530 00:01:54.540 goes into it the circuit board part of
00:01:56.840 00:01:56.850 it brings power to whatever is calling
00:01:58.639 00:01:58.649 for power like the blower motor or the
00:02:00.499 00:02:00.509 inducer igniter so what will happen is
00:02:02.990 00:02:03.000 sometimes let's say during the AC season
00:02:05.990 00:02:06.000 the AC outside will turn on everything
00:02:08.930 00:02:08.940 seems to be working good but the blower
00:02:10.639 00:02:10.649 motor inside of the furnace is not
00:02:11.930 00:02:11.940 turning on sometimes what's wrong is
00:02:14.059 00:02:14.069 that
00:02:14.300 00:02:14.310 the board is not sending power to the
00:02:15.949 00:02:15.959 blower motor and simply not powering it
00:02:17.900 00:02:17.910 up or other times you have voltage
00:02:19.970 00:02:19.980 coming in from the transformer 24 volts
00:02:22.790 00:02:22.800 into the control board
00:02:24.050 00:02:24.060 but then that voltage does not come back
00:02:26.089 00:02:26.099 out that means there's some kind of a
00:02:28.190 00:02:28.200 circuit or a diode or some of resistor
00:02:31.130 00:02:31.140 inside the board that got burnt out so
00:02:33.080 00:02:33.090 in a nutshell how I was taught is if
00:02:35.930 00:02:35.940 there's power going in but no power
00:02:38.059 00:02:38.069 coming out that means the board is bad
00:02:40.160 00:02:40.170 so what I like to do when I start is I
00:02:42.440 00:02:42.450 set my meter to voltage my door switch
00:02:45.140 00:02:45.150 is taped shut so I have power going
00:02:47.150 00:02:47.160 through I like to first verify that my
00:02:49.460 00:02:49.470 furnace is getting power and a lot of
00:02:51.979 00:02:51.989 times a good indicator will be the
00:02:54.559 00:02:54.569 indicator light the diagnostic indicator
00:02:56.690 00:02:56.700 light if that's blinking then most
00:02:59.000 00:02:59.010 likely you do have power you have 120
00:03:00.860 00:03:00.870 volts and you have 24 volts but not all
00:03:03.500 00:03:03.510 furnaces will have that light so what I
00:03:05.420 00:03:05.430 like to do is check it quick so if you
00:03:08.180 00:03:08.190 pull off the wire that goes to your line
00:03:10.670 00:03:10.680 terminal from the door switch to our
00:03:13.400 00:03:13.410 line terminal just pull that off stick
00:03:18.710 00:03:18.720 one meter lead in there and with your
00:03:21.770 00:03:21.780 other terminal you need to find a common
00:03:24.050 00:03:24.060 somewhere I like to just use a the
00:03:27.319 00:03:27.329 comment on the transformer just because
00:03:29.180 00:03:29.190 it's more accessible than the rest of
00:03:30.860 00:03:30.870 them and if you just stick your lead
00:03:32.900 00:03:32.910 into the middle speed of that
00:03:35.030 00:03:35.040 transformer common there you should get
00:03:38.539 00:03:38.549 a hundred twenty volts so if you look at
00:03:40.250 00:03:40.260 my meter
00:03:42.370 00:03:42.380 you see 120 volts so from my line
00:03:47.080 00:03:47.090 terminal to a common you're supposed to
00:03:49.970 00:03:49.980 have 120 volts and I do have voltage
00:03:51.860 00:03:51.870 there and that means my furnace is
00:03:53.960 00:03:53.970 getting power and it's getting past that
00:03:55.670 00:03:55.680 door switch so I can plug that back in
00:03:58.960 00:03:58.970 next what I like to check is that my
00:04:02.120 00:04:02.130 transformer is getting 120 volts as well
00:04:05.539 00:04:05.549 so I'd like to loosen the connectors on
00:04:07.970 00:04:07.980 the transformer black and white that's
00:04:10.640 00:04:10.650 going to be your 120 volt side usually
00:04:12.890 00:04:12.900 it's a black and white wire I like to
00:04:15.500 00:04:15.510 just leave them like half on plug like
00:04:17.840 00:04:17.850 that so I could put my meter leads on
00:04:23.689 00:04:23.699 so you put one lead on the Colin from
00:04:26.219 00:04:26.229 the transformer and one lead on the
00:04:29.689 00:04:29.699 primary hot side and if you look at my
00:04:32.730 00:04:32.740 meter you got 120 volts so the board is
00:04:37.290 00:04:37.300 sending power to the transformer now if
00:04:42.030 00:04:42.040 your board is getting powered if you
00:04:45.330 00:04:45.340 check your line voltage on your line
00:04:47.189 00:04:47.199 terminal and it's getting 120 volts but
00:04:49.890 00:04:49.900 it's not sending power to your
00:04:51.270 00:04:51.280 transformer so if you check the white
00:04:53.340 00:04:53.350 and black on the transformer and there's
00:04:54.719 00:04:54.729 no 120 volts then your board is bad and
00:04:57.750 00:04:57.760 it's not sending power to that
00:04:59.010 00:04:59.020 transformer next thing you want to check
00:05:01.290 00:05:01.300 is the secondary side of your
00:05:02.700 00:05:02.710 transformer so it transforms at 120
00:05:05.100 00:05:05.110 volts into 24 volts so if you go on this
00:05:08.520 00:05:08.530 side usually I mean there are always
00:05:10.980 00:05:10.990 different colors the secondary side
00:05:12.629 00:05:12.639 lines the secondary side wires but they
00:05:16.770 00:05:16.780 will be opposite of the 120 volts side
00:05:19.110 00:05:19.120 if you put both of your leads on those
00:05:21.740 00:05:21.750 you should have somewhere around 24
00:05:24.839 00:05:24.849 volts and there you go I have 28 volts
00:05:28.620 00:05:28.630 so my transformer is sending 28 volts
00:05:31.830 00:05:31.840 out and also there's a fuse in line with
00:05:35.339 00:05:35.349 that sometimes it'll be on the board I
00:05:37.529 00:05:37.539 don't have a place for it on the board
00:05:39.480 00:05:39.490 so mine is placed in on the hot side
00:05:41.760 00:05:41.770 coming from the transformer the 24 volt
00:05:43.890 00:05:43.900 side and then what I'd like to do is
00:05:45.900 00:05:45.910 track where those 24 Volt wires from the
00:05:48.240 00:05:48.250 transformer go in my case it goes into
00:05:51.210 00:05:51.220 the one side goes into the fuse my fuse
00:05:53.219 00:05:53.229 is good goes out the other end and goes
00:05:55.529 00:05:55.539 into the small X plug then the other
00:05:57.689 00:05:57.699 wire right here the common also goes
00:06:01.170 00:06:01.180 into the small X plug so the 24 volt
00:06:03.990 00:06:04.000 wires go straight into the control ward
00:06:05.850 00:06:05.860 sometimes they'll have their own
00:06:07.020 00:06:07.030 terminals it'll be called secondary one
00:06:09.210 00:06:09.220 and secondary two so if I put my meter
00:06:11.490 00:06:11.500 leads into the molex plug a hot side and
00:06:15.570 00:06:15.580 the common
00:06:19.120 00:06:19.130 as you can see I have 28 volts going
00:06:22.450 00:06:22.460 into the control board and after the 28
00:06:26.590 00:06:26.600 volts goes into the control board it
00:06:28.540 00:06:28.550 will come out on the thermostat terminal
00:06:31.030 00:06:31.040 strip which is right down here in mine
00:06:33.130 00:06:33.140 it will look different on every furnace
00:06:35.680 00:06:35.690 but for the most part it'll be in a row
00:06:37.570 00:06:37.580 like this where it says WY RG c it for
00:06:42.250 00:06:42.260 common so the next thing you want to
00:06:43.600 00:06:43.610 check is R which is power to common or b
00:06:48.430 00:06:48.440 or c sometimes do so if I check voltage
00:06:53.080 00:06:53.090 between R and common as you can see on
00:06:56.080 00:06:56.090 00:06:56.530 00:06:56.540 I do have 28 volts so the board received
00:06:59.920 00:06:59.930 28 volts and it's putting out 28 volts
00:07:03.280 00:07:03.290 at that terminal strip now if you're
00:07:05.740 00:07:05.750 getting voltage that far then chances
00:07:07.990 00:07:08.000 are your control board is good usually
00:07:09.940 00:07:09.950 you're gonna lose voltage somewhere
00:07:11.770 00:07:11.780 before that also what you can find
00:07:13.570 00:07:13.580 helpful is on the back of your furnace
00:07:15.550 00:07:15.560 door most of the time there will be a
00:07:16.990 00:07:17.000 wiring schematic and it could be hard to
00:07:19.960 00:07:19.970 follow like mine for example has a bunch
00:07:22.270 00:07:22.280 of lines and stuff but if you look at
00:07:25.060 00:07:25.070 just look on the schematic until you
00:07:27.490 00:07:27.500 find the power supply which in my case
00:07:29.440 00:07:29.450 is right here look for the black and
00:07:31.420 00:07:31.430 white and then you can kind of follow
00:07:32.920 00:07:32.930 those lines where they go into the board
00:07:34.660 00:07:34.670 and I'll explain sometimes what color
00:07:37.240 00:07:37.250 those wires are what terminals they go
00:07:39.550 00:07:39.560 into and you know sometimes it will help
00:07:42.160 00:07:42.170 you track down on the wires that way
00:07:43.830 00:07:43.840 also if you do end up needing a new
00:07:46.210 00:07:46.220 control board the way you go about
00:07:48.400 00:07:48.410 looking for the new replacement board
00:07:50.290 00:07:50.300 most of the time on the board itself
00:07:52.600 00:07:52.610 it'll tell you it's model number or part
00:07:54.400 00:07:54.410 number and in my case it even tells me
00:07:56.560 00:07:56.570 replace with CNT to 184 so if I ever
00:08:00.430 00:08:00.440 needed a new board all I had to do is
00:08:01.930 00:08:01.940 look up this board right here and get it
00:08:03.640 00:08:03.650 on Amazon or whatever and that is the
00:08:06.010 00:08:06.020 basics of troubleshooting your control
00:08:07.720 00:08:07.730 board sometimes it'll be some goofy
00:08:09.730 00:08:09.740 situation and then it's not as easy to
00:08:11.560 00:08:11.570 troubleshoot and you do kind of have to
00:08:13.240 00:08:13.250 go case by case basis but for the most
00:08:15.820 00:08:15.830 part if you follow that procedure you
00:08:17.620 00:08:17.630 will be able to figure out if your board
00:08:19.630 00:08:19.640 bet is bad or not so once again as a
00:08:22.120 00:08:22.130 reminder if you have power going into it
00:08:24.040 00:08:24.050 but it's not sending power out the board
00:08:26.710 00:08:26.720 is bad same for a furnace for example if
00:08:29.770 00:08:29.780 you have power going into it but it's
00:08:31.390 00:08:31.400 not sending power to
00:08:33.040 00:08:33.050 let's say your inducer motor or your
00:08:35.380 00:08:35.390 igniter then your board is bad I hope
00:08:38.440 00:08:38.450 that makes sense to you if you didn't
00:08:39.910 00:08:39.920 quite get it you can ask me in the
00:08:41.050 00:08:41.060 comments below and I'll try to explain
00:08:42.310 00:08:42.320 it better down there and that is all I
00:08:44.350 00:08:44.360 had for you today thank you so much for
00:08:45.850 00:08:45.860 watching don't forget to match that like
00:08:47.290 00:08:47.300 button on your way out and we'll see you
00:08:48.760 00:08:48.770 next time
00:08:50.200 00:08:50.210 [Music]
00:09:07.060 00:09:07.070 you
Office location
Engineering company LOTUS®
Russia, Ekaterinburg, Lunacharskogo street, 240/12

Phone: +7 343 216 77 75

E-mail: info@lotus1.ru

Sales phone

Russia: +7 343 216 77 75

WhatsApp: +79122710308