Forgive me if this question has been asked before. I searched but did not find a clear answer. So my question is for maybe one of you guys that has been to Ford. Or anybody who knows. Why did they not use an electric a/c compressor?? It seems that it would be better for fuel econ to have a small motor driving it rather than the ICE. But please feel free to correct me if i'm wrong!

 

Depends... if you are running it only when the engine is running then its better to get that energy directly rather than to convert it to eletricity and back. Its rather complicated. I'm not saying its an automatic win to run it off the engine, just that its simplistic to assume an electric motor would be more efficient. The electricity still has to come from the engine.

 

The short answer is:

There's NO REAL ADVANTAGE TO IT!

 

It seems rather silly that the A/C is powered off of the ICE, especially since Toyota has been using electric for the A/C for several years now and even other car companies are starting to run the A/C and even power steering electrically. It sure would be nice to be able to run my defrosters or the A/C without having to keep the ICE running. Heck, run it off of the HV system and it would be nearly free to run the A/C.

On a side topic, is there any way to get the defrosters to run without the A/C compressor and ICE running?

 

I have to agree. IMHO, it would have been better for the A/C compressor to have run off electric rather than only off the ICE. Fixing that design error, would have been a good improvement for the '08 redesign.

I add to this, that for '08, even the gas-only models have switched from an ICE powered power steering, to the electric power steering the hybrids have been using all along. So, ti seems that there is value with having electric driven accessories instead of ICE driven.

 

When the ambient temperature is below 20 degrees Fahrenheit (I think- some frigid temp), the defroster will run without the compressor. That's the only way I know.

 

When I got my '05, I assumed the lack of electric AC was simply to expedite the release of the truck. Now I can only assume that they are putting all their hybrid energy into the upcoming hybrid Fusion.

But I share your frustration. It definitely seems silly by this time.

 

Having just got an '08 MMH 2x4 knowing that this is a compromise, I just _know_ that they'll make the a/c all electric next year. Then I'll be sitting in traffic fuming about it. Literally.

Then again, there's no way I was buying a Prius just to get some cool air -- not when I could have the hybrid SUV

 

Thing is the A/C requires a great deal more power to turn the compressor than the power steering. In fact the A/C can't even run at idle on a normal car, the vehicle has to bump up the idle speed.

Now take into account that MOST of the time the engine is on, so most of the time you can take that energy directly from the ICE..... So you can loose the advantage of taking the power directly 80% of the time, and not have A/C 20% of the time when you are on electric or you can run your A/C all the time on electric by charging the battery through the generator, with all the losses.... the energy in that battery is NOT free, converting it to A/C power means you'll have less to drive the vehicle and it will cost MPG. Its entirely possible they ran the numbers (they should have) and found that running the A/C off the electric was a loss MPG wise. I say its a little presumptuous of us to claim it was the WRONG thing to do without the benefit of knowing the numbers that the engineers would have.

 

It's more efficient to run accessories from the ICE if the ICE is running anyway. But accessories, like power steering, that need to work when the ICE is off need to be driven electrically so they can be independent of the ICE. The non-hybrid FE switch to electric power steering may have more to do with manufacturing efficiencies and reducing unique parts than with it being "better".