It simply means the PSU is bad. You need to contact who you bought it from and get a new one. I'm going to assume they are Bel Power Solutions PET1300-12-054NA PSUs and that they are used?! They are good PSUs, no doubt. But if you want them to continue to work and be power houses, I highly recommend you take off the top cover open up the plastic underneath and get a tank of compressed air and blow them out really, really good. Otherwise, they will just suffocate or dust will collect somewhere too much and create a contact and short out your PSU.

Edit: also you may want to check the contacts in the back and make sure none of them are bent.