For those of you with temp gauges, does it matter whether the A/C is on cold or hot when it comes to cooling the engine? I usually turn the A/C on heat to get the fans blowing and pull the hot air out of the engine bay (does this make sense?). So my real question is, does having the A/C on cold or hot affect the engine's coolant temp.

 

Well if you turn it to hot obviously this will help engine temps more than if you turn it to cold . Turning it to hot is basically using the heater, so your A/C compressor will not engage, instead you'll route coolant through the heater core. This is great if you ever start to overheat because it acts as a second radiator. That and the fans still come on I believe, so this is the most amount of cooling capacity you can get (for the engine). If you have it on cold, then the compressor starts up and you'll get hot freon going through the condensor, this adds heat to the system, but since the fans are on at the same time you sould actually run cooler temps than with everything turned off. I always run 180-190F with the A/C on cold due to the fans running.

 

Thanks ...that's exactly what I wanted to know.