Bring a large pot of water to a boil, then add the elbow macaroni and cook until al dente, about 8 minutes. Stir occasionally to prevent sticking and test for doneness by tasting; the pasta should be tender but still firm.
Drain the cooked pasta in a colander and rinse thoroughly under cold running water until it feels cool and stops steaming, about 2 minutes. Shake off excess water and transfer the pasta to a large mixing bowl.
Add the mayonnaise and apple cider vinegar to the cooled pasta. Mix gently with a spoon or spatula until the pasta is evenly coated with the creamy dressing, creating a slick, glossy appearance.
Stir in the diced celery, shredded carrots, chopped ham, and finely diced onion. Continue folding until all ingredients are well combined, and you see a colorful, textured mixture.
Taste the salad and adjust seasoning if needed—add a splash more vinegar or a pinch of salt if desired. Cover the bowl with plastic wrap and refrigerate for at least 1 hour to allow flavors to meld and the salad to chill thoroughly.
Once chilled, give the salad a gentle stir, check the seasoning, and serve cold. The finished Hawaiian Macaroni Salad should be bright, creamy, and packed with crunch, ready to enjoy as a flavorful side or light main dish.
