back to the drawing board


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Old 08-07-09, 08:03 PM
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back to the drawing board

I posted during the week. I have the unit that won't turn on outside, but inside unit (comfortmaker) won't turn off. I replaced the circuit board, but have the same problem. I'm puzzled. I have 27 volts coming out of the transformer. Could the extra 3 volts cause my problem or is that normal? I still don't have any volts on my low voltage wires on the board that go to the thermostat. I have no clue! help please!
thanks,
Brian
 
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Old 08-08-09, 10:40 AM
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The 27 volts is not the issue. How many volts do you have from R to C terminals on the board?
 
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Old 08-08-09, 01:35 PM
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Originally Posted by daddyjohn
The 27 volts is not the issue. How many volts do you have from R to C terminals on the board?
0..I don't have any volts from r-c. Also, my new board did come with a fuse....fuse hasn't blown.
 
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Old 08-08-09, 06:30 PM
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I think you have an open high limit switch on your inside unit.
If this is a gas fired furnace the limit will be located on the firewall. Could also be spill switches around the burner box.
 
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Old 08-08-09, 08:13 PM
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sounds like you got no satisfaction on your earlier in the week thread. Lets just start from scratch. If you go outside and push in the contactor does the outside unit run both fan and compressor?
 
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Old 08-09-09, 07:15 AM
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Originally Posted by Skip4661
I think you have an open high limit switch on your inside unit.
If this is a gas fired furnace the limit will be located on the firewall. Could also be spill switches around the burner box.
ok..I appreciate your help in tryin' to fix this. Yes, it is a gas fired furnace. I have (3) what I feel are limit switches...one on the firewall with a red wire going to the board and another leading to a limit located near the blower fan. I have another limit located just above the gas pilot light with a red wire also going to the board and the other also going to the switch near the blower fan. Do you know which might be my problem..also I have the same unit in my attic for the upstairs that works fine..before I buy another part do you think it would be wise to remove from their to try out on my problem ac unit?
 
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Old 08-09-09, 07:19 AM
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Originally Posted by Former Member
sounds like you got no satisfaction on your earlier in the week thread. Lets just start from scratch. If you go outside and push in the contactor does the outside unit run both fan and compressor?
I actually haven't focused any attention to my outside unit. I have 27 volts going to my newly replaced circuit board, yet don't have any volts on my low voltage wires...
 
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Old 08-09-09, 08:14 AM
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Your jumping around too much

Start from the begining. Know what you should have and where and then what you actually have. First, place the meter in AC volts, then, kill the power to furnace. Remove the thermostat cover or mounting screws till you can see the wire connections. take a digital photo of what is there OR write down which wire goes where THEN remove the wiring exposing the bare wires. This is all low voltage wires and won't shock you. Next, connect the following wires together, Red, yellow and green under one wire nut or just twist them together. The AC should run within 5 minutes (inside fan, outdoor compressor and outdoor fan). If it does the unit is operating as it should. Do this first and report back the results.
 
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Old 08-09-09, 10:40 AM
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hvac...getting same response. inside won't turn off.
 
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Old 08-09-09, 12:56 PM
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inside fan still running

this is not important as yet....is the OUTDOOR unit running at all? if not, while it is still jumped, do you have 24V to the outdoor contactor coil? or does the 2 wires that go outside, go to a board first?
 

Last edited by hvac01453; 08-09-09 at 01:14 PM. Reason: correction
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Old 08-09-09, 02:30 PM
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Originally Posted by hvac01453
this is not important as yet....is the OUTDOOR unit running at all? if not, while it is still jumped, do you have 24V to the outdoor contactor coil? or does the 2 wires that go outside, go to a board first?
not sure if you read all the prior posts...I have 24 volts coming off the transformer going to board..I'm not getting any volts on the low voltage wires on the board. skipp was asking about the limit switches....could that be my trouble?
 
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Old 08-09-09, 05:05 PM
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I was doing some googling...Is it safe to take the 2 wires going to the limit switch on the firewall and connect them to bypass the limit switch to test if that's bad?
 
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Old 08-09-09, 05:32 PM
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think I got it...not sure what it's called to order it. I took the limit switch off the firewall to inspect it. It seem ok and replaced it. The (switch?) just above my pilot light flame ( it has 2 red wires..one leading to the board and the other to another switch up top near the small blower fan..it's like a round button about 1" dia. by 1" deep with a smaller little button thing on top) seemed like it had some wiggle to it. as I went to pull off one of the red wires....it easily cracked and came off..it broke. I can now see inside and it has small copper contacts...it seems like it's not getting contact..it seems open. I know I need that part regardless so do you know what it's called???? and could that have been my trouble????
 
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Old 08-09-09, 05:58 PM
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That would be called a spill switch or flame roll switch. Your wiring schematic should tell you which it is.
 
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Old 08-09-09, 06:35 PM
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A safety

It sounds like some kind of safety switch. Shut off the gas valve (just in case) and if its a Klixon safety, jump it out just to see if its the problem is OK, but don't walk away from it like that. It sounds to me like a high limit safety. They usually have a reset button in the middle....some have auto reset though... A spill switch is always manual lock out.
When you said you had no 24V where were your probes connected to?
 
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Old 08-09-09, 06:38 PM
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24Volts...???

If you don't have 24Volts, how is the fan running?
 
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Old 08-09-09, 06:42 PM
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27 volts

just because 27 VAC is coming out of the transformer doesn't mean its going anywhere, the fuse is likely blown, OHM out the fuse on the board. Is this a grounded transformer?
 
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Old 08-09-09, 07:35 PM
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I traced it out and it is the roll out switch....Weather that's the problem or not I'll order a new one tomorrow cause like I said it's broke. Hvac...did you say I can jump it out? To make certain I understand...I can take the 2 wires and connect them ....turn it on for a few minutes to try it out??? thanks again for all the helpful info. everyone.
and...I have 24 volts leaving the transformer and going to the board, but no volts on the low voltage wires on the board. There wasn't a fuse on the old board, but I replaced it the other day and new one has a fuse...not blown.
 
 

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