To repair an air mattress without patching it, identify the leaking area or hole, and use glue to stick a piece of thick plastic over the top of it. An alternative is to identify the leak or hole, and cover it securely with a piece of duct tape. However, duct tape is more of a temporary fix because the mattress is likely to continue to leak slowly.
When repairing a leak in an air mattress without patching it, use a thick piece of plastic such as a small piece of shower curtain or tarp. It is also important to use heavy-duty glue or super glue. Not all glue is strong enough to keep the plastic in place well enough to block the leak.
Find the leak by first listening for a steady hissing sound coming from a specific area. If this method fails, try submerging small portions of the mattress in water to watch for air bubbles. Air bubbles indicate the leak. If this is not an option, put soap suds on small portions of the mattress until air from the leak visibly moves the suds. If no leak is located, consider any sudden temperature change. Temperature changes can modify the air pressure in air mattresses.