Outside unit does not run, probed voltage from two 110v fuses of powerbox to contactor, probed 24v to contactor from thermostat when ac is turned on, watched contactor close when unit is turned on at thermostat, probed 110v on each side of contactor when it is closed, probed wires, to both compressor,fan and dual capacitor from contactor 110v on both sides for a total of 220v to compressor and fan. Some rust but no bulges on capacitor,replaced it anyway. Unit still will not run. What am I missing? unclebobsouth

 

did you put in a new stat if so it might be wired wrong

 

Do you read 220V for sure at the contactor when it pulls in. You say 110V each leg but you could have a 110V feed back there. Your unit dont have a high head reset some where????

ED

 

Thank you Ed Imeduc! I must have been reading residual voltage from the capacitor all the way up to the control box fuse. I disconnected the compressor-fan side of the contactor and the voltage dropped off on one leg. A fuse from the fuse box that supplys the voltage to the control box of the outside unit was blown. Strange that the control box fuse didn't blow. The bad news is that I think the compressor is blowing the fuse. I replaced the bad fuse, verified the voltage to the power side of the contactor,powered up the contactor which resulted in an arc in the vicinity of the compressor blowing the same fuse again. I inspected the wires to the compressor but cannot find any indications of a short. This is a 1998 Lennox outside unit. I don't know if the compressor has servicable contacts or if the compressor has grenaded. Thanks for ya'lls time unclebobsouth