Originally posted by 1stGenCRXer
Unless the air conditioning is turned on seperately, the compressor is never turned when you hit the defrost/defog button [at least that is true for abou 80% of 4-cylinder vehicles on the road today, V-6 and V-8 cars are a little different],
Actually, I challenge you to try it. When you push the defrost button to redirect air flow to the front windshield, the A/C is on. My buddy's 90 Accord does it, so does my Integra. That's how defrosters are designed to work.
BTW, I'm glad you mentioned the eddy current dynos. I haven't had the chance to use one, they're still very much high $$ equipment, but I do understand that they also have a few problems. Namely, since you're measureing the current draw of [effectively] and electric engine, you run the risk of having a bush bounce on the commutator, causing a carbon arc, which will cause irregular current draw, and skew the results :a:
Are you sure about the commutator. I couldn't imagine using a brush generator in there. If carbon arcing is truly a problem why wouldn't the manufacturer be using an AC "alternator"?? Eddy currents result from simply moving a magnet near a conductor. Sooo, it could be a completely mechanical system, I'm not familiar with automobile ones, but small table top eddy current dynos measure torque based on the physical proximity of permanent magnets to a rotating conductor.