My control board burned out and I replaced it. My furnace and ac still remain inop-I also replaced the thermostat with a known good one and I wired the new board exactly like my old one was wired. If I go out to the compressor and push the contactor on manually to start the unit, the fan runs but I cant tell if the compressor is kicking on or not. My lines dont get cold and heat will blow from the vents. Also the only way my blower comes on is if I turn it on at the switch. I have spoken to the parts place and they believe I may have had a lightning strike on the ground near my house and that may have caused the board to burn out. What else should I check and where can I get a diagram for my intertherm unit. It is a 1995 year model and the number on the furnace unit is E1EH-815HA.
To see if it is the t-stat or the system you can unwire the entire t-stat and jump out the wires. never touch the blue to any other wire or you will blow the low voltage fuse on new board. if you jump red to yellow and your condensing unit cycles on the t-stat is wired wrong or wrong style. If not go check the yellow wire at cond. unit and see if power is even going to it.
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Let is set for awhile, may have tripped the Breaker or it is in Time Delay. The new AC's have a time delay built into the board if the power is interupted if won't start the compressor right away. Or you could of also had a power surge and burned out the control board on the AC or Furnace. Recheck the thermostat to see if you are still calling for Cooling. Hope this helps.....
The G terminal on the thermostat most go to the G terminal on the control board, so the green wire that is attached to the G terminal on the subbase of the thermostat must go to the G terminal on the intergrated control board on the furnace. I will post a pic of how the wiring goes
if this is a split system, go to the furnace or air handler. Shut off the power, remove blower door and find where thermostat wires go to control module.
Remove thermostat wires writing down where each one goes. Make a jumper wire and install it between r and y or r and y1.Put everything back together and turn on power. IF blower motor and ac start, you have
a low voltage wiring or thermostat problem.
If nothing happens then you either have no power to furnace, transformer
could be bad or you have blown a little 3amp automotive fuse that is
installed on the control board.
Try cycling the switch at the furnace to reset the blower board. If this doesn't work remove the green wire from the blower board(computer board) to eliminate a shorted t-stat or shorted wire between the furance and t-stat. If blower remains on, then blower board is shorted. I've seen all these problems.
We hotwired the thermostat wires and the furnace started. That told us that the problem was with the thermostat. We took our remote control to another camper like ours and our remote worked their furnace. That told us that the problem was in the ceiling control for the furnace/ac. But the man who owned the other camper told us that he had a problem, too, and was told to unplug all the electric including the battery, wait 2 minutes, and hook up again. This might reprogram the circuitboard, and voila! It worked.
Check your furnace for power. will be 4 wires. power ground and 2 thermostat wires. Check for power at the time delay relay, if you have power there check for power going in the fan motor, if power in motor wire, motor is bad. If no power in motor wire and power going to circuit board take the 2 thermostat wire apart and wrap the 2 together comimg from the thermostat. Fan will stat in about 30 seconds. If it does you need a control kit in the ac. But sounds to me like you have a furnace problem.
The problem is most likely in the control module of the roof air unit. Dometic uses the thermostat to activate and deactivate a relay in the control board of the roof ac unit whiich is just visible when you remove your air intake screen. The two blue with white stripe wires are the furnace control wires.
The furnace turns on and off by the opening and closing of relay. Most likely, the furnace control relay is stuck in the on position. On the thermostate, remove the fur wire and see if the furnace quits afrer it cycles down...it does not quit right away. With the termostat out of the loop, if the furnace does not shut down, the problem is in the control box. They are not hard to replace but you must be careful with the live wiire from the 110 ciucuit breaker. If you are not comfortable with the repair, take it to a dealer. The part number is on the assembly box. They need to know if you have the heat srip option or whatever othert options our Roof AC has. If the furnace still runs with the blue/white wires disconnected, the furnace wires are shorted somewhere between the furnace and the AC control unit.