24 Volt not reaching T-Stats
#1
07-19-15, 12:05 PM
24 Volt not reaching T-Stats
Problem was my condensing unit fan was not spinning.
- Tested 24 volt going through contact came out nothing
- Tested 24 volt going through my T-stats and came out nothing
- Tested 24 volt going through my Transformer Out and I do see the 24 volts
- Flashing red and green light
What would be my next step?
- Tested 24 volt going through contact came out nothing
- Tested 24 volt going through my T-stats and came out nothing
- Tested 24 volt going through my Transformer Out and I do see the 24 volts
- Flashing red and green light
What would be my next step?
#2
07-19-15, 12:11 PM
Member
Are the flashing Red/Green lights on your furnace control board? If so, what does your furnace manual say it means? Also, have you checked to see if there is a fuse on your furnace control board? Many newer furnaces fuse the 24VAC line so that a short circuit on the 24V line doesn't damage the transformer.
#3
07-19-15, 12:36 PM
The Flashing red and green light mean its normal, as for the fuse I'm not sure which one it is. If i have to assume its the purple tab with the 3 on my picture. I have not check the fuse to see if its burnt or anything. I tested the blue and yellow wire coming out from the transformer and that's where i see the 24 volts if that's how you correctly test it.
#4
07-19-15, 12:40 PM
Member
I don't see a picture, however 3A is a common fuse amperage for the 24V fuse. If the fuse is blown, you'll need to find out why, as fuses rarely blow for no reason.
#5
07-19-15, 12:48 PM
Forum Topic Moderator
The outdoor fan motor is not spinning.
Does the compressor outside run with a cooling demand?
Does the indoor fan turn off and on from the thermostat?
You tested the transformer correctly but did you measure R to C at the furnace terminals with the door switch depressed?
Sounds like you have a Lennox furnace.
Does the compressor outside run with a cooling demand?
Does the indoor fan turn off and on from the thermostat?
You tested the transformer correctly but did you measure R to C at the furnace terminals with the door switch depressed?
Sounds like you have a Lennox furnace.
#8
07-19-15, 12:57 PM
Forum Topic Moderator
Your pictures are coming thru now.
I haven't been able to find a Lennox diagnostic code chart that lists open fuse?
That is strange.
I take it that you have power between R and C at the furnace?
I haven't been able to find a Lennox diagnostic code chart that lists open fuse?
That is strange.
I take it that you have power between R and C at the furnace?
#9
07-19-15, 01:03 PM
Member
I'm seeing the images now also. As Houston said, did you measure the 24VAC between the R & C terminals on the terminal strip near the bottom of the board (as shown in your picture)? As Houston also mentioned, you need to tape the door switch closed so that the furnace is powered up.
#10
07-19-15, 05:18 PM
OK, so I made a mistake on the test earlier while I was outside at the condenser.
So the brown wire coming up is from the inside Furnace, if I put my leads on the two orange tab inside I would get my 24 volts.
[ATTACH=CONFIG]53570[/ATTACH]
Now if you looked at my previous picture the black wire that goes into the tab stays black coming out, as for the white wire it becomes yellow. Now that yellow wire goes down to this green thing and out and into the contacter.
[ATTACH=CONFIG]53572[/ATTACH]
[ATTACH=CONFIG]53573[/ATTACH]
If I put my leads on the blue and black wire while its pulled off. I would read 10 volts. But if I would put my leads on the two contact while its both clip on, I would read zero.
[ATTACH=CONFIG]53571[/ATTACH]
So my question is my contactor the problem or that green thing? Because if I push my contactor down, everything will work. But since the 24 volts isn't going through to pull the magnet down it won't work.
So the brown wire coming up is from the inside Furnace, if I put my leads on the two orange tab inside I would get my 24 volts.
[ATTACH=CONFIG]53570[/ATTACH]
Now if you looked at my previous picture the black wire that goes into the tab stays black coming out, as for the white wire it becomes yellow. Now that yellow wire goes down to this green thing and out and into the contacter.
[ATTACH=CONFIG]53572[/ATTACH]
[ATTACH=CONFIG]53573[/ATTACH]
If I put my leads on the blue and black wire while its pulled off. I would read 10 volts. But if I would put my leads on the two contact while its both clip on, I would read zero.
[ATTACH=CONFIG]53571[/ATTACH]
So my question is my contactor the problem or that green thing? Because if I push my contactor down, everything will work. But since the 24 volts isn't going through to pull the magnet down it won't work.
#12
07-19-15, 05:44 PM
Its too late for me to test it now, ill have to test it tomorrow. When you say the reset switch I'm going to assume the red button on top of it? Do I just hit it once or hold it or something?
#14
07-19-15, 07:49 PM
Group Moderator
#16
07-20-15, 04:49 AM
Forum Topic Moderator
Does the run capacitor appear swollen on the terminal side?
A weak cap can trip that pressure switch.
A weak cap can trip that pressure switch.
#18
07-21-15, 10:09 PM
Group Moderator
Hitting the High Pressure Safety Switch worked. It fixed the problem
Houston mentioned an issue above and if not that..... you could be having a problem with the condenser fan.
