Don't know if we've discussed this elsewhere, Mike (too many forums! :-)

They are not seperate systems. They are one and the same, there is simply a valve mechanism under the hood which determines whether the refrigerant goes to the passenger compartment, the battery cooler, or both.

As to why this system was chosen, only the engineers can answer. Someone at some point decided to use outside air for the battery, and that drove a whole set of requirements that resulted in this HVAC system. Toyota sidestepped this problem by using cabin air for the battery, assuming the passengers would want to keep themselves cool and would thus cool the battery at the same time. Also helps to keep the battery warm in winter. As to why Ford didn't use an electric compressor like Prius II, I'd bet Toyota has patent protection on the eletrically-driven compressor in the current model Prius and Ford didn't want to license that patent (or the HVAC work was already completed by the time they learned of it). Consider the battery cooling system (and the entire cooling package, btw) was outsourced to Visteon (there's a press release about it on their website) so it may well have been that Ford already had 20,000 battery cooling units in warehouse long before the cars started rolling off the line.

 

Wow! I was very wrong about FEH climate control. Frankly I don't understand how Ford is getting the system to not hit the engine compartment constantly for A/C use if the climate control system is manual?

 

I'm not an expert on patent law, but if patent law is being followed correctly, which is debateable consider the history of software related and Microsoft related lawsuits, then Ford could have used and electric a/c compressor.

Patent law is about patenting a product or specific process, not a concept. The concept of electric a/c compressors has been around for a very long time. Home and building a/c is electrically based, so the concept is general knoweldge and implemented in many different fashions by many different manufacturers. Patent infringement could have happened if Ford had directly copied the mechanics behind the Toyota electric a/c system. But if Ford had chosen to take an existing compressor they had around and electrified it, or designed their own and then placed it in the climate system for the vehicle, that wouldn't be patent infringement because they did their own homework and created their own device to acomplish the same goal.

 

The way the service manual reads, it suggests when not in MAX AC or DEFROST mode, the compressor will not engage unless the engine is running. OTOH, the battery can command an engine start to run the compressor. So, if it's not so hot out that the battery is getting too warm, the A/C would theoretically have no effect on the engine. If it's warm enough that this would become a problem, odds are the battery temperature sensor is already requesting cooling, so the engine will run.

Summer will tell us if it actually works this way.

 

I am not an expert either, but if they had independently "invented" the idea of using an electric scroll compressor in a car and could verify that claim, they would be able to implement it without licensing any patents from Toyota. However, considering that Ford did license other patents from Toyota in spite of developing their own hybrid technology, it seems to me that the lawyers might have insisted on licensing any patents around the HVAC system too.