John, Look in your center vents with a flashlight and see what is going on. Some people miss the obvious: There are thumbwheel operated shutters in each vent. Run these up & down to make sure they work and that they are open. Just forward of these vents you should see a yellow wall of foam. This is a flapper door that is hinged at the top. It blocks the dash vents in the following conditions: engine not running (no vacuum), mode switch in OFF, HEATER or DEFROST position. If this flapper door never opens then you have a vacuum problem. Your hissing noise is a sure symptom. Follow your ears to the source. You will probably need to remove the center console to get good access. Follow the two vacuum lines from the engine compartment along the left side of the console. One supplies vacuum to the mode switch in the dash; the other supplies vacuum from the mode switch back to the heater valve in the engine compartment. Check to make sure they are all secure. The next thing to suspect is a dried out or dirty mode switch. They are easy to disassemble & clean. Check the diaphragm to be sure it isn't torn and that the tits haven't sheared off. Give it a light coating of silicone o-ring lubricant and reassemble. If little air is getting out anywhere then has it ever worked well? You may have the wrong type of blower motor installed. It is a GM part but looks identical to the more common blower that spins the other way. Some people realize this and run the motors reverse polarity. But if they also replaced the squirrel cage then most likely the blades are facing the wrong direction. Any combination of wrong spin direction or wrong squirrel cage will blow some air but not quite like it should. I'm sure there are several DeLorean owners with this situation that don't know any better. Remove your a/c blower and test it with a battery. Negative goes to the case and positive goes to the insulated spade lug terminal. The squirrel cage should spin in a counter clockwise direction (when viewed from the top). If not then you have the wrong kind of motor. Also check to see that you have the right kind of squirrel cage. In the center where it bolts to the motor you should see an arrow pointing in the direction of proper rotation which in the case of the DeLorean is counter clockwise. > One other strange thing that happens is that if I have it on fan > speed setting 4, sometimes the motor will vary speed all by itself, > almost like an engine revving up and down, what is making it do > this????? This sounds like a problem that is unrelated to your vacuum leak. There are two well known electrical gremlins with the a/c blower. First is that the circuit breaker is underrated. Second is the cheap relays controlling fan speeds 3 & 4. If you buy the "vendor approved" relay upgrade package, it should come with new circuit breakers for the a/c blower and the radiator fans. They are common items at auto parts stores. The OEM breaker for the blower is 25 amps. This should be replaced with one rated at 30 amps. Even if yours was replaced, it may have been wired in backwards. This will cause it to get too hot and work erratically. Walt To unsubscribe from this group, send an email to: DMCForum-unsubscribe@xxxxxxxxxxxxxxx Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
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