Bryant Central AC - indoor blower won't start, outdoor unit comes on fine
#1
06-23-12, 07:45 PM
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Bryant Central AC - indoor blower won't start, outdoor unit comes on fine
System is about 8-10 years old. First time to use it this year, the air handler fan won't come on, and the outside unit works fine. The indoor air handler is in the attic. The thermostat is a battery digital setback type.
I've:
There are three conductor thermostat wires going to the thermostat and the outside unit. Once set of wires has one wire turned back and wrapped around the insulation. It was my understanding that this set the two wires go to the outside unit, the set with using all three go to the thermostat. I think the two wires to the outside complete the thermostat circuit by going through high and low pressure switches.
I suspected that the low voltage wires to the outdoor unit could have been chewed through this winter by a squirrel in the chase where the run from the unit to the attic and I can't easily access that to check. I bypassed this outer circuit and connected the two thermostat wires together and it instantly blew the 5A fuse. (Oh cr@p, did I make things worse?). Then it dawned on me I could check for continuity on the two wires set and I have continuity. I also have continuity on a pair of wires going to the thermostat.
The HVAC company that installed the system is backed up for several weeks before they can send someone, and we have company coming. Looking for any and all suggestions and help
Thank you,
Paul
I've:
- Ensured the thermostat was set to a lower temperature so it will call for cool.
- Replaced the thermostat batteries.
- Ensured the cutoff switch near the air handler is on.
- Spun the blower squirrel cage fan by hand and it spins freely.
- Checked voltage coming in to the unit and it was > 200V.
- The motor does not hum or make any sound. (So not likely the hard start capacitor right?)
- Set the thermostat from fan to auto, no change.
- Checked the 5A fuse in the air handler. (more about that below)
There are three conductor thermostat wires going to the thermostat and the outside unit. Once set of wires has one wire turned back and wrapped around the insulation. It was my understanding that this set the two wires go to the outside unit, the set with using all three go to the thermostat. I think the two wires to the outside complete the thermostat circuit by going through high and low pressure switches.
I suspected that the low voltage wires to the outdoor unit could have been chewed through this winter by a squirrel in the chase where the run from the unit to the attic and I can't easily access that to check. I bypassed this outer circuit and connected the two thermostat wires together and it instantly blew the 5A fuse. (Oh cr@p, did I make things worse?). Then it dawned on me I could check for continuity on the two wires set and I have continuity. I also have continuity on a pair of wires going to the thermostat.
The HVAC company that installed the system is backed up for several weeks before they can send someone, and we have company coming. Looking for any and all suggestions and help
Thank you,
Paul
#2
06-25-12, 02:30 PM
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Hi all,
It's supposed to be hot again later this week and our company arrives late tonight. Hoping someone has some advise for me I have the same airhandler downstairs and can switch out parts. I've have a ohm meter and can test voltages, but wasn't sure which wires should be what. I can also post a picture if that helps.
Thanks in advance!
Paul
It's supposed to be hot again later this week and our company arrives late tonight. Hoping someone has some advise for me I have the same airhandler downstairs and can switch out parts. I've have a ohm meter and can test voltages, but wasn't sure which wires should be what. I can also post a picture if that helps.
Thanks in advance!
Paul
#3
06-25-12, 03:18 PM
Member
set the thermostat to system off and fan ON... Does the motor run? If no, jumper R to G at the thermostat terminals, does it run now?
#4
06-25-12, 05:26 PM
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Sorry, which red/green
System turned off at the thermostat, fan set to auto, the fan does not start.
Sorry, which red/green?
I have two sets of thermostat wires with red/green/white One goes to the outside unit, the other the thermostat. Not sure which is which.
Set 1
Red <-> Red
Green <-> Grey
White <-> Green on second set of thermostat wires
Set 2
Red <-> Brown
Green <-> White from Set 1
White <-> Tied off, not connected
Yesterday I connected two wires and blew the 5 am fuse. I'm pretty sure it was Red and Brown but I'm not positive.
Thank you!
Paul
Sorry, which red/green?
I have two sets of thermostat wires with red/green/white One goes to the outside unit, the other the thermostat. Not sure which is which.
Set 1
Red <-> Red
Green <-> Grey
White <-> Green on second set of thermostat wires
Set 2
Red <-> Brown
Green <-> White from Set 1
White <-> Tied off, not connected
Yesterday I connected two wires and blew the 5 am fuse. I'm pretty sure it was Red and Brown but I'm not positive.
Thank you!
Paul
#7
06-25-12, 06:24 PM
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I found the install manual
http://www.docs.hvacpartners.com/idc...im-fa4a-04.pdf
If I understand it correctly, the test will be to connect red and gray from the fan control together with unit off at thermostat and fan set to ON. Is that correct?
If I understand it correctly, the test will be to connect red and gray from the fan control together with unit off at thermostat and fan set to ON. Is that correct?
#8
06-25-12, 06:53 PM
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still no go
I connected the Red and Grey wires for the fan speed control with the fan set to ON and system set to off. Fan motor did not move.
#9
06-26-12, 02:48 AM
Member
Who said anything about red or green or gray? There are terminals designated R and G. You need to call a pro if you are unwilling to follow directions.
#10
06-26-12, 09:17 AM
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My mistake, I see now you stated R G terminals. I was looking at wires, as the unit is mounted horizontally, on the floor to actually see the fan control board I need to lay down on the floor and look up at it. I connected the wires terminating at R and G and the fan did not spin or hum.
When I get home tonight, I will disconnect any wires from R and G and jumper R and G.
What's next?
As far as calling in a professional, as I mentioned in my first post, I've called but they are scheduling two-three weeks out. I tried a second company yesterday, who services my oil burner, and they are backed up at least another week.
Thank you,
Paul
When I get home tonight, I will disconnect any wires from R and G and jumper R and G.
What's next?
As far as calling in a professional, as I mentioned in my first post, I've called but they are scheduling two-three weeks out. I tried a second company yesterday, who services my oil burner, and they are backed up at least another week.
Thank you,
Paul
#12
06-26-12, 12:31 PM
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hvactecfw,
My wife just called to tell me it has started working. I had left it with the fan switch on the thermostat set to ON last night.
Would that indicate that the PCB board or the transformer might be flaky? Can I assume the fan motor is not likely the problem?
Thanks again for your assistance!!
Paul
My wife just called to tell me it has started working. I had left it with the fan switch on the thermostat set to ON last night.
Would that indicate that the PCB board or the transformer might be flaky? Can I assume the fan motor is not likely the problem?
Thanks again for your assistance!!
Paul
#13
06-26-12, 01:55 PM
Member
It would seem that way. If it happens again and while fan is set to on then check voltage between G and C at the control board while holding the door switch in.
