I have a Lennox 10ACB42-11P outside unit and it just quit working yesterday (fan and compressor do not kick-in).
Upon checking with multimeter, seems like I am not getting 24V at the contactor for some reason. When I manually press and hold the contactor with a insulated screwdriver the compressor and fan kicks in. I have also replaced the dual run capacitor also.
When, I shorted the wire at the thermostat Y & Rc, nothing happens. I am thinking, maybe the 24 volt transformer located in the attic furnace maybe bad. Any ideas what should I do next?
FYI, when I change the thermostat setting to FAN from AUTO, the blower fan also does not come in.
First thing I'd investigate is whether there is 120V at the furnace, (don't forget the 120V runs through the access door switch). 2nd would be to look for a blown fuse on the computer board in the furnace. If the fuse is blown, the next question is why.
Just because you can, doesn't always mean you should