My central heating and air unit went out I've used my financial hardship to help purchase my home I was wondering can I use my 401k disability withdrawal to purchase another unit when I'm not disable

Are you still working for the firm that holds your 401(k)? How old are you? Are you actually disabled? There is no such thing as a disability withdrawal from a 401(k). You are allowed to withdraw, but with penalties under certain conditions. Home repairs, however are not usually an acceptable condition.

You may take a penalty-free withdrawal from your 401(k) if you are permanently and totally disabled. It would require certification from your doctor of your disability, and of course you must be unable to work. If you are not permanently and totally disabled, then no, you can't claim that you are. It would be better to use your plan's loan feature, if it has one - you can borrow up to 50% of the value in your 401(k) without penalty and without having to pay income taxes on it. In general it's much wiser to take a loan from your 401(k) while still working as opposed to a withdrawal.