AC and Fuel Mileage ?s

[KrazyKarl84]

I'm going to try not to beat a dead horse, and i searched the forums before deciding to post, but I'd rather ask a few questions which may not sound smart then make a few mistakes that aren't so smart.

I've got a 97 ranger, 2wd, 2.3L, Auto Trans (recently rebuilt) with about 150K on it. Its somewhat of a daily driver (I split the load with a beater 93 saturn that is rapidly dying) and I plan on having it for a good long time to come (hence putting in the rebuilt trans earlier this summer)

My main question is about the AC and how it relates to fuel mileage-every time its been used, the truck seems to really bog down-given that its a standard cab and I have the sliding rear window, even living for a few years in florida I hardly ever used it. It also seems as though the AC kicks on somewhat randomly and the truck noticeably shudders a bit when it does-you can tell when the AC clutch is engauging. I'm curious if disabling or removing the AC will improve the fuel economy/idling of the engine? I get that the AC compressor is needed to dry the air for defrosting, but I think I can manage without. I was told that one possible solution would be to just "unplug" the AC, but I'm a little hesitant to just start pulling out wiring connections from the AC. I've also thought about just yanking the whole thing, but have heard that the replacement "dummy" pulleys that sit in the compressors place are kind of weak. Any thoughts on this ? The AC kicking on/AC clutch kicking in drives me nuts seeing the engine kind of buck and idle like it does, and I've toyed with the idea of getting rid of the AC since I bought the truck back in 2005. The truck gets pretty decent fuel economy as is ( 23-29, and I've coaxed 30/31 out of it on a long highway trip at 55) but with the impending death of my saturn (189k, a massive crack in the windshield, and rotting/rusting front part of the roof that prevents replacement of the windshield) and a 40+ mile commute each way, If I can coax a bit better fuel mileage out of it then I'd like too.

Also, any thoughts on using any sort of "performance chip" to increase fuel economy? I'm not worried about horsepower or going fast, saving money right now is my main issue (being employed only part time and having student loan repayment coming up in november will do that) I'm guessing any sort of chip would probably cost more then its worth, but figured I'd ask as you folks seem pretty knowledgable.

Any other tips for improving fuel mileage for these trucks? (I'm guessing no, since if it were easy the factory may have done it) I tend to take it easy on the city roads and highway as it is (cruise between 60 & 64 ish) From what Iv'e been reading on here seems most economy/performace gains require extensive/expensive rebuildling/work, but again, figured I'd ask.

Thanks for the help, also, as for additional info about the truck, I'm pretty good about regular oil changes/prevenative maintenence, did all 8 plugs back in june after getting the trans in (wires in 2005 after purchasing it), truck needs a cat back exhaust within the year (small leak behind the muffler, and the tail pipe gone now thanks to rust and michigan roads) but otherwise, its in solid shape other then a few dents and dings from being used.....as a truck....

Thanks for any and all help.

Karl

 

[scotts90ranger]

just unplug the AC clutch, it's the one connector just behind the pulley, that will keep it from kicking on and off randomly and it won't care... just leaving the compressor there won't hurt anything, the pulley has bearings in it so it free spins, no extra drag on the engine, just a few extra pounds under the hood.

as far as maintenance, the only other thing I would look into would be the timing belt, on that year they are rated for about 130K, it's a non interference engine but replacing it before it breaks and leaves you stranded is always good

 

[Ranger44]

Is it a shudder? Or is it just a sudden drag?

If it's the drag, that's normal.

If it's a shudder, I'd suspect a worn or bad clutch that's preventing proper and smooth engagement.

The A/C compressor when engaged shouldn't cost you too much mileage. Maybe 1 mpg.

Also the compressor should only be kicking on in a/c or defrost modes. If it's in the off position, you shouldn't have anything to worry about.

Speaking of defrost mode, and having A/C greatly increases the effectiveness of the defrost/defog. I've driven both setups in the same year range of trucks (93-94'). The non-A/C isn't fun when it's raining outside, hot and humid, and the windshield isn't defogging. Your only hope is to have a towel in the cab to wipe the window down.....repeatedly. SO, I highly recommend just keeping the A/C.

 

[locovaca]

Is it a shudder? Or is it just a sudden drag?

If it's the drag, that's normal.

If it's a shudder, I'd suspect a worn or bad clutch that's preventing proper and smooth engagement.

The A/C compressor when engaged shouldn't cost you too much mileage. Maybe 1 mpg.

Also the compressor should only be kicking on in a/c or defrost modes. If it's in the off position, you shouldn't have anything to worry about.

Speaking of defrost mode, and having A/C greatly increases the effectiveness of the defrost/defog. I've driven both setups in the same year range of trucks (93-94'). The non-A/C isn't fun when it's raining outside, hot and humid, and the windshield isn't defogging. Your only hope is to have a towel in the cab to wipe the window down.....repeatedly. SO, I highly recommend just keeping the A/C.

On a 2.3 it costs more than 1 mpg unless you're simply cruising on the flattest interstate in the US. With only 100 or so horsies, the extra drag really takes any oomph the engine had.

A properly working compressor pulley has no extra drag than an idler pulley. However, if your compressor is cycling in and out frequently you may want to check your freon charge to make sure it's up to spec.

A performance chip *may* help, but not by any sort of margin you're looking for. The ranges you posted are pretty much it for a 2.3; getting 30 or 31 is extremely good (my best is 26, but I do have a topper).

I put in an Explorer Message Center and Taurus Digital Cluster; I have the MC showing average MPG and the cluster showing instantaneous MPG. This alone gave me a 1-2 MPG increase because it showed me, real time, what my foot was doing. If you're really desperate for MPGs, what you need to do is:

1. Do 55 and nothing over
2. Drive like a granny up to that 55
3. Drive within a "MPG range." Meaning, I don't let the throttle go past a certain point. That means, going up hills, I may lose 5 mph, but going down hills I may gain 10-15 mph. Of course, this doesn't work if you're driving on a crowded interstate but on the relatively deserted highways of Iowa, it works well.
4. Use 5th gear for anything 55 and above. No, you don't have a lot of power, but I found from my MPG calculators that 5th definitely has an improvement over 4th, even if it takes you 50 years to gain speed (see #3).


You could, of course, go extreme in losing extra weight like the passenger's seat, removing the bed, etc. if you're super desperate. But again, from what you posted, your MPGs are extremely good, especially for an auto.