Quick fuel saving tip for Winter

[Johnny Mullet]

If you have a vehicle that has A/C and would like to save fuel during the coming winter months, then do like I do and unplug the A/C compressor or remove the relay/fuse. Most vehicles are made to engage the compressor when in "Defrost" or other modes on your climate control selector, and this will waste fuel.

Some may argue and say.............

"Not running the compressor clutch will make it go bad!" - Then why do junkyards sell them?
"That freon has to circulate during winter!" - Just like it does in my A/C machine?
"The defroster will not work correctly!" - Um, what?

All incorrect statements. I have done this for years on all vehicles I owned with A/C and never had any problems at all. Not to say that maybe some newer vehicles with complex heater control systems (Volvo XC90, Cadillac, Lincoln, etc) will show some sort of fault, but if you are driving one of those puppies, then you seriously need to rethink what you are driving if you are planning to attempt a mod like this to save fuel.

An even better way to do this would be to purchase a belt for a non-A/C vehicle and bypass the compressor, but this does not work on some vehicles depending on the belt routing.

This mod along with installing a block heater to keep the engine warm and for warmer startups, a grill block, under hood insulation (if not equipped), etc will really help you in the fuel saving department over time.

Discuss.

[RH77]

Great idea I vote for a switch, just in case...

Luckily my car has a switch to engage/disengage the compressor while directing air to the defrost vents.

When the car is parked outside for a few days, I like having the option -- if a bunch of snow gets in, starts to melt, and fogs up the works and just breathing does it too.

More on the reason: the extended parking situation (airport) offers no outlet for the block heater, so it takes a loooong time to heat up. I'd crack the window to let the dry air fix the situation, but the combination of continuing to freeze my arse, not letting the temp get up to allow TC lockup, and robbing the engine's heat is the 3rd strike. Even with a winter grille block, it's tough to get that heat. I hit the highway immediately in this case.

The worst situation last Winter: scraping a 1/2" layer of ice off of the glass, the temp dropped to the teens so it was freezing, and I don't idle the car to warm it up.

I'm sure there's a solution -- any thoughts? (other than being tougher in the cold -- I know )

RH77

[bluesfan]

Originally Posted by Johnny Mullet

If you have a vehicle that has A/C and would like to save fuel during the coming winter months, then do like I do and unplug the A/C compressor or remove the relay/fuse. Most vehicles are made to engage the compressor when in "Defrost" or other modes on your climate control selector, and this will waste fuel.

....

An even better way to do this would be to purchase a belt for a non-A/C vehicle and bypass the compressor, but this does not work on some vehicles depending on the belt routing.

This mod along with installing a block heater to keep the engine warm and for warmer startups, a grill block, under hood insulation (if not equipped), etc will really help you in the fuel saving department over time.

Discuss.

Thanks for this JM.

I checked out the manual for my truck, and it looks like there is a fuse and a relay for the A/C clutch solenoid. My guess is that popping the fuse would disable the A/C -- it will be easy to test that.

I will explore the belt swap option as well. If anyone here has a recent B-series Mazda or a Ranger, I would like to know if you have any experience with swapping belts.

My 2008 B2300 came with a block heater, so that piece is covered. I will likely buy a timer so it switches on at 5 am or so -- two hours before I leave for work.

The grill block idea is straightforward, but under-hood insulation is a new concept for me. Can someone explain what it would look like so I can see if I am factory-equipped in that area?

EDIT: I get it now -- insulating the underside of the hood. "I was associating "under the hood" with the entire engine compartment...

Thanks,

bluesfan

[bbjsw10]

Great idea Johhny, too bad I don't have a/c. I do like the idea of adding underhood insulation, do you guys think the silver backed house insulation would do the trick? I have some of that laying around, some liquid nails and stick it in place,,,?

[dentprone]

Definitely...run a switch in the dash to make the process even easier. I suppose a relay would be really sweet, but add another link to the chain. Here in FL, though, I have always appreciated the A/C running with the defrost...seems to help cut the 100% freakin' humidity we have.

[dentprone]

Originally Posted by bbjsw10

Great idea Johhny, too bad I don't have a/c. I do like the idea of adding underhood insulation, do you guys think the silver backed house insulation would do the trick? I have some of that laying around, some liquid nails and stick it in place,,,?

Is it the thin bubble wrap type? I always wanted to stitch up a reversible hat out of that stuff, with one side dark fabric, other reflective. But then I think of all the tinfoil hat jokes..... I think liquid nails would hold it just fine on the hood, seems to be fairly high heat stuff.

[Will]

Excellent topic. I do this to my wife's Buick every year.

[MazdaMatt]

Originally Posted by RH77

The worst situation last Winter: scraping a 1/2" layer of ice off of the glass, the temp dropped to the teens

Well booo-fricken-hoooo... this IS an international forum remember! I'm not even in the "extreme north" and last winter we had a week where the temp didn't get above -30C... try THAT and tell me I shouldn't idle my car for a bit!

As for the compressor, i wouldn't turn it off because it blows dry air on my window for defog. Without it I'm screwed.

[Daox]

Great suggestion Johnny. I'll definitly have to do this to the Matrix this winter. I like RH77's suggestion about the switch too. Its nice to have the defrost for summer when its rainy or super humid out. But, in winter its totally unnecessary. Too bad they don't let you have the choice from the factory.

[MazdaMatt]

Originally Posted by Daox

in winter its totally unnecessary

Huh???

[Daox]

I meant that dehumidified defrost air (from the a/c running) is not necessary in winter because the air is already dry.

[MazdaMatt]

some days its dry, but i wouldn't be able to say that I get 4 months of continuous dry cold. I think it is retarded that cars don't seperate fan control and compressor control anymore. I hate that I can't decide for myself if i want the compressor on... it's a waste of gas.

[Daox]

I've never had a problem defrosting windows in my cars that didn't have A/C.

[mavinwy]

Weird...

I was considering this just last night while putting a new electric fan set in the Neon.

Since the fuse for the AC is underhood, I was just planning on putting it on a rocker switch so that I could pick and choose when to run the AC since the new fan control module does not activate the fan yet. Then I thought...why not leave it that way for the winter.

I ran the wires last night, but the auto parts store was out of the switches to match the ones I currently have installed, so it will wait a day or two.

I feel a little dumb about not coming up with this before since I helped a buddy of mine put his AC on a rocker switch on his 2000 Protoge because the PO had some "intersting" wiring going to it and some auto controls missing. It works fine and is "on demand" and he can even turn it off on some of the long hills around here.

Oh well, better late than never.....

Jim

[wagonman76]

Mine defrosts just fine without AC. The only car I have where the AC even works is the Celebrity and I put that one away for winter. I think carmakers make the AC run with defrost for defogging, not necessarily for defrosting. Up in the north you dont need it, since any fog just becomes frost anyway and yes it the air is very dry in the winter.

Id disconnect the wire to the compressor clutch too in the winter if mine worked.

[Markmysite]

Hmmm never thought to try this. Any idea how much improvement in mileage it would net?

[Noel]

AC helping get the moisture off the window helps a LOT.
Many a day that just a defroster along won't keep the window from fogging up.

I have a button to controll ac compressor.

Originally Posted by Daox

I meant that dehumidified defrost air (from the a/c running) is not necessary in winter because the air is already dry.

[RH77]

Originally Posted by MazdaMatt

Well booo-fricken-hoooo... this IS an international forum remember! I'm not even in the "extreme north" and last winter we had a week where the temp didn't get above -30C... try THAT and tell me I shouldn't idle my car for a bit!

Didn't you read the disclaimer
I'm just not dressed for the occasion after a work trip. We also get a lot of wind (which I didn't factor into experience). I think there's a tolerance that's built-up in either extremes as well.

I've spent some time in the -30/-40C range, but dressed for it. Here, the temp ranges from -5F to 105F, sorry -21C to 41C since this IS an International forum

Now, can I talk you to into driving in 35C/70% relative humidity, without A/C?

As for the compressor, i wouldn't turn it off because it blows dry air on my window for defog. Without it I'm screwed.

See below...

Originally Posted by Daox

I've never had a problem defrosting windows in my cars that didn't have A/C.

Same here -- it just takes some extra effort in controls/windows and/or paper towels.

As mentioned, the switch does offer the option to cut the A/C on hills when you need it. For my job, I can't show up a sweaty mess -- so before I get pummeled for that, I do use the A/C. Otherwise, I'll often sweat it out on the way home or in personal use. The condenser hangs-on to the cool air pretty well with the re-circ on.

The previous gen. Taurus (200x-2006) drove me nuts! The compressor came on in all selectors but "Floor" (and off). You couldn't direct cool air through the vents to save on drag (windows down) without engaging the compressor. That car seriously needs a switch.

Lots of newer cars (even base models with air -- specifically GM) will not allow recirc without the compressor engaged. The new Galant turns on the A/C automatically on recirc engage, but you can turn it off. Too bad you have to lean down to see the recirc indicator light in the daytime. They don't let you do anything on your own anymore.

RH77

[MazdaMatt]

Originally Posted by RH77

Now, can I talk you to into driving in 35C/70% relative humidity, without A/C?

In S.Ontario we range from -40 to +40. Rare on the extremes, but they happen. I'm skinny, i don't mind 35* (find it kinda pleasant), but i HATE -35 with a passion. Skinny fingers were not intended to grip -35 steering wheels.

As for the compressor topic... my compressor DOES turn on in floor mode, but it allows foot/face and face without and turns on for face/defog and defog. Bloody annoying!

Yes, SOMETIMES blowing air over your wet carpets will fog your windows, but let me decide that, cuz the other 99% of the time, i'd rather have the compressor OFF. I guess they figure if they can prevent ONE accident because some moron kept fogging up their windows, it is worth everyone using more gas.

[Daox]

I've always just been able to crank the heat and fan on high and not have a problem at all. Of course, that car has a wonderfully large fan on it...