Keystone air conditioner produces a high-pitched squealing or screeching noise when the fan runs.

Safety: Disconnect power before touching any moving parts.

Steps:

• Identify source: Determine whether the noise comes from the indoor blower or outdoor fan by listening from each side.
• Check for rubbing: Inspect fan blades and blower wheel for contact with the housing. Adjust position or tighten mounting screws.
• Temporary lubrication: For motors with oil ports, apply a few drops of light machine oil to the bearings. This may provide short-term relief but is not a permanent fix.
• Replace motor: If noise persists, replace the noisy fan motor with a Keystone-compatible motor assembly.