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Discussion Starter #1
I didn't really think about it too much till the other day when I posted about my fuel mileage. Heres my issue. Today driving into work I averaged 35.3mpg with no a/c on. When I turn on my a/c I get about 18mpg. Is this normal? I just contributed it to being a 4cyl. Also with no a/c on the car runs between 198-202 degrees. With the a/c on it runs from 207-215 degrees. Any thoughts?
 

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Discussion Starter #2
Of course I might add that every light was green on my 27 mile commute today. Normally I would get about 30-31mpg...
 

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same reaction the 30 seems right for 70 to 74 mph with cruise set and flat ground, I have wondered the same thing so I set the cc on flat ground (easy to find in ohio) and then engage ac no change ... maybe 1 mpg this is with the instant mpg feature . have no clue why the big drop. temo is a lil higher with ac on , have never seen an 11 deg jump but never really checked
 

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Can't speak to the GXP ghost, but my N/A ran 28-30 mpg on last summer's road trip, a mix of A/C on and off. (Same 1 mpg variance between on and off.)

The A/C compressor is a parasitic load, but it sounds like yours is a bigger parasite than most. Going bad perhaps? I don't know if there is a "torque" rating for how freely it should spin when engaged.
 

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Discussion Starter #6
Can't speak to the GXP ghost, but my N/A ran 28-30 mpg on last summer's road trip, a mix of A/C on and off. (Same 1 mpg variance between on and off.)

The A/C compressor is a parasitic load, but it sounds like yours is a bigger parasite than most. Going bad perhaps? I don't know if there is a "torque" rating for how freely it should spin when engaged.
I was thinking that Chicken... I do notice that after I get past 2500rpm with the A/C on, it gives a good whine. So maybe I'm low on freon. I will say that the 95 degree days we had, I turned it to #3 after about 10 minutes for the rest of the ride home, unless I was at a light and it started getting warm from lack of rpms....
 

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IF the mileage drop with AC is correct, then the only blame is the compressor. You can prove that by running the vent only and noting no drop in MPGs. A bad compressor will also chew through the belt quickly. Inspect that for wear.
 

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I notice no real difference with or without a/c. Current tank, and I am driving a little easier to see what it will do, is 27.8 in town. Over 30 highway. A/ makes no difference. Sounds like you have a compressor problem. Mine still runs at 199-201 in Phoenix. Hot and humid today, 105 degrees. My a/c temp stays the same driving or stopped at LOOONG lights in Phoenix.
 

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Since we're on the topic of A/C, I can't say I have noticed a drop in MPG, but the car does seem to perform differently with the A/C on. I know this can be the case in many cars, which is why when racing or driving spirited the A/C will typically be turned off, but do you notice this as well? The car is sluggish on acceleration and will bog down upon a normal start from 0, more so than normal.
 

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Discussion Starter #10
Since we're on the topic of A/C, I can't say I have noticed a drop in MPG, but the car does seem to perform differently with the A/C on. I know this can be the case in many cars, which is why when racing or driving spirited the A/C will typically be turned off, but do you notice this as well? The car is sluggish on acceleration and will bog down upon a normal start from 0, more so than normal.
I notice a touch difference in performance, but nothing major. Of course mine is a GXP so the turbo makes up for the power loss. My issue is with my gas mileage!
 

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My GXP is reading 18.3 mostly all the time. I think its excessive, but no cel or other reason to think a problem exists, new air filter , no change. Mine only varies 18.3 to 18.4 MPG. Uhg! I probly need to spend some cash and get it on a Dynomometer.
 

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Is that city driving Bill? If so, your about right, especially if you have a heavy foot. Since this post I've really watched my mpg... I get 23 - 27 in mixed driving (I drive 15 minutes in city and 15 on freeway to and from work). It all depends on which season the gas companies are in...winter brew or summer brew... the summer gives a much better mpg....

My best mileage was during an hour stint at 80mph....I reset it just to see what mileage I got and I averaged 37mpg for that hour....
 

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Yes, thats driving around town, keeping a light foot. Now after a new air filter I'm getting a steady 18.7 MPG on the info-meter. Soon my new scanner will arrive and I'll learn it.
Maxidas DS708


I'm in TampaBay, Florida
 
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