I know they are a parasite on a gasser but I am wondering if the A/C has much of an affect on the mileage on our trucks. I really can't feel it come on and off but where I live it runs almost anytime the truck is on?
My mileage seems to be falling off a bit at 17.5 and I was getting 19. I am also wondering if my PG-7 Is the culprit.
I want 20 and I want it-w-14 second performance.
Where can I get the TSB's for a 2004?
Sorry for all the questions.

 

I do believe that every accessory does use more fuel. The fan is also a big draw. How much on a diesel is unknown to me.

 

I lose about 10% when running AC. When I am towing that is about 1 mpg. You do pay something for keeping cool.

Casey

 

Well, if you are talking city driving, then YES the A/C will kill your mileage. Now let's talk highway, actually you fuel milage will be better with the A/C on due to less drag from haveing a window open. If you check wiht anyone that runs wind tunnel test on cars and trucks they will tell you that they are performed with the windows up to get better air flow. Your more expensive cars such as Volvo and Mecedes has an A/C OFF button and not a button to turn it on. They are on all the time.
On the highway run it if you need it the CTD needs that extra drag to make it feel gooooood

 

I'm wondering if I should take my truck in to be looked at. When I turn on the A/C I can *definitely* feel that's it on...I lose quite a bit of power in the city. It also makes a totally different noise when the A/C's engaged - a LOUD blowing noise that increases with RPM...any idea what this could be?

On the highway, I don't notice much power loss, the noise, or significantly reduced mileage - just when starting from a dead stop in 2nd and then the shift up to 3rd gear.

 

You are probably hearing your fan which would be on with the air on. Mine gets pretty loud and you discribe it well.

Generally it takes about 10 to 15 horsepower to run the ac. This is true if you have a pinto or a Ram. The four cylinder gas engine will use a lot more gas to keep it going where the Cummins will not be as affected. I really don't see much big difference with it on or off. This is probaly because like was mentioned, if the air is off you usually have a window open, that messes the air flow.

It also depends on the moisture and heat that you are trying to cool. Using max air is more economy based. Remember you are taking the heat out of the air inside and pumping it outside in front of the radiator. The less it has to remove the less it works. When you are not on max air it is cooling and removing the moisture out of the outside air and pumping that air inside. Essentially you do not have an air conditioner but a de-humidifier. Costs more to ac the air in Florida than Arizona.

 

I use the max setting until I get sick of the noxious smell. I have tried heating up the ducts-w- the heater but it didn't help. Any other suggestions?

 

Take it back to the dealer and get them to remove that dead shunk

 

On a recent run to Vegas, with ac, about 50 miles of mountain driving from 4,000 to 10,000 feet, cruising about 70 to 74 at 2000 to 2100 rpm, I was getting 20 mpg. I can feel a slight drop in power when the ac is activated, but it didn't seem to bother the mpg's. I also ran with the windows down when the temps were in the 80's
(I dislike ac , but I'm grateful for it when the temps bump over 85!) with my head hanging out the window and my slober pasting the car behind me, I still was getting 20 mpg

 

I've never noticed a substatial change due to my AC being on. I could be wrong, but I still get about 16.5-17 MPG whether the AC is on or off.

 

I lose about 1 mpg or so on the slab with the AC on.