95 Altima, the 10 amp AC fuse keeps blowing witch also effects the controls for switching between heat and cooling (only allows heat to come out) and also the buttons that change were the air comes out of. Any ideas of what to check in order to find what may be causing the problem?

UPDATE;

I replaced the 10 amp fuse and removed the AC relay from under the hood and now the fues does not blow.
Does the AC protect it self if its low on coolant?