93 1500 suburban problem any help appreciated

Just picked up a 93 suburban 1500 series last weekend. It has the 350cuin and runs incredible. Every thing worked until today rear air all of a sudden quit working. Tryied using overhead controls up front to control rear and no go as well as using rear controls no go again.

I pulled the fuse marked rr hvac and it was fine. Any suggestions as the culprit. No noise just noticed it was no longer working. Front a ir freezes me out but the kids complained today that it was not working or I would of never noticed.

Any tips on trouble shooting this out.

Check and make sure the rear blower motor has power to it with a test light. If it does then the blower is bad