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A/C or Heat does not work w/thermostat set "on" or "auto".
A/C or Heat doesnt work in "on" or "auto". Fan will not come on at the "on" position either. I changed the batteries in the thermostat. I also read somewhere to disconnect the "Y" and hold it to the "R" on the thermostat for two minutes. That will tell me if the thermostat is the problem. Still nothing worked. I checked to make sure the outlet the furnace was plugged into had power...it does. I then removed the cover from the circuit board on the central air unit. It is a Ducane, it has a Honeywell circuit board. I looked at that wiring for a little while and decided to remove the in coming hot and the "cool" wire leading to the fan. I wired those together and the fan came on. I then (by mistake) put the cool lead back in place but accidently put it on the "continuous on" lead. The fan turned on and wouldn't turn off, can you imagine? After that I cut power and put it back the way it's supposed to be...nothing. Does this mean the circuit board is bad? Or a relay on the board? What is the next step? Replace the board? Or am I completely off base?
thank you for any help you can give.
Jumper R to G at the unit. (do not forget to make sure door swith is closed, use tape) If the fan runs go to the thermostat jumper R to G. If the fan runs from the board and not the t-stat you have a bad wire connection from t-stat to unit. If the fan does not run from jumping R to G at the board it may be a bad board or relay let us know.
Ok, here is the deal, I have done R to G, and R to W. I did not do R to Y. I have also switched the "hot" black wire on the circuit board marked "cool" to the "cont" and the fan comes on to run continuous. Also, i have checked that the safety switch for the door access panel is functioning properly so that isn't the problem. If I have taken these steps is it safe to assume that the circuit board is the problem and needs to be replaced? What does the transformer do? Could it have any part of this? Please give any advice on what to check next to make sure I don't order a $200 part and it not be the problem. I sure appreciate it.
It is not smart to buy a circuit board until you have exhausted all other possibilities for problems. You say you did R to G and R to W but you didn't say what happened when you did that. So what happened when you connecter R to G on the circuit board.?? The main blower motor should have started, Did it??? When you touched R to W on the circuit the hot surface igniter should have begun to glow if all things were right. So if these things didn't happen then it is possible that it is the circuit board if it is not the transformer.
You ask what the transformer does. It changes 120 volts into 24 volts. Your furnace has two different wiring systems. the high voltage operates the two fan motors and the 24 volts operate all of the controls. Also something you have not mentioned is a fuse that is on the circuit board. If you have a short in your low voltage wiring this fuse will blow.
I really appreciate the help, nothing happened with the R to G and R to W combos. The 5 amp fuse is in tact on the circuit board as well. What else can i do? How do you check the transformer?
With the power off pull the 5 amp fuse and look at it close. Is it burnt in the middle? If not put it back in place and turn power on check voltage from R to C if you do not have 24 volts check sec 1 and sec 2 on the control board if you do not have 24 volts check L1 and L2 do you have power(115 volts)? If you have it at L1 and L2 and not at sec 1 and sec 2 you have a bad transformer. (power needs to be on and the bottom door switch closed to do this test) If you have it at sec 1 and 2 and not at R and C you have a open limit switch. Good luck and let us know.
Here is what I've got and don't got.
Fuse is good.
No Voltage at R and C. If I understand what SEC 1 and 2 is, There is no voltage there. I checked Sec X (the 24v output from the transformer, no voltage there. I have 115 at what is calls "s1" and "s2" on my circuit board (s1 being the main power supply to the board, s2 being the output to the transformer. Basically, 115 going into the transformer, nothing coming out.
So...I need a transformer? Or I need to double check something?
After that I cut power and put it back the way it's supposed to be...nothing. Does this mean the circuit board is bad? Or a relay on the board? What is the next step? Replace the board? Or am I completely off base?
Linear Mode
