I disconnected the central air conditioner long ago during the initial phase of my home renovation. I am preparing to hook it up again and have a technician come out to look at it. The original wire is 10/3 with ground but the grounding wire is 14 gauge. They originally installed a small disconnect box in the basement with another wire heading out to the panel outside. I purchased some new 10/3 for the part after the disconnect, and noticed the ground which is 10 gauge (no surprise). Would it be problematic on this type of circuit (dedicated) to use the new 10 gauge ground with the older 14 gauge ground?
Using a larger ground conductor is fine. Using a smaller gauge wire for grounding was common in the past, but not correct anymore. The grounding conductor should be at least as large as the other conductors.