My 85 300zx did something wierd this morning. I ran it with the AC for the first 5 minutes , she started blowing hot air. I shut the AC off, restarted it and it was blowing Ice cold for the remainder of the the 15 minute ride. I am just about to check the vaccum hoses, which I know most Z's have the problem of blowing hot air when you step on the gas. Should I check the AC belt, any suggestions, anything to look for ?