Returned to a commercial site in Tracy California to complete needed repairs on two Lennox units. Our tech replaced the condenser fan motor and blade on RTU#4. Unit is functional, but found that the relay for the #2 fan motor is sticking. Will return to replace before total failure. Moved on to troubleshoot RTU#5, discovered the VFD had failed. Ordered VFD through supplier. Will return when VFD arrives.