How to defeat the A/C on with defrost nonsense
 

anyone do this? is it possible? also, the can't use recirc with A/C either. Damn these engineers!

Huh?? :scratchhe
Yous drunk, isn't ya :mchase:

hoe?

The reason you want the outside air on during the defrost cycle is because it is dryer than the inside air. It is the inside air that fog/frosted your windows to begin with.
Clearing the morning frost should be done with a scraper. If you are trying to do that primarily with your defroster, then you are warming your car for too long of a time and wasting gas.

Easy. Pull the A/C relay in the fuse box. Flip it upside down and push it back into the spot to store it. Come springtime, flip and install again. That keeps the compressor from coming on. I've done it every year for the last three years.

:yelrotflmActually I was not drunk when I typed this. I wanna keep the A/C--not pull the fuse-- but 75% of the time when I put it on defrost I do NOT want to clear the windshield, its the just the way i want the air distributed.

You don't need the A/C compressor in Winter. Heat alone will defog your windshield. Your choices are A/C compressor on whenever heat or defrost is selected, or pull the relay and it won't come on.

Eventually I'm going to add a switch that will be a "true" A/C switch like cars should have instead of the automatic safety nanny. *I* decide when the compressor comes on. It will be three-position: Normal operation, Off, On. There will be a light to indicate when the compressor is actually engaged.

Just be aware weather factors in some places mean the ac can help dehumidify. Where you live probably is not the same weather as other places. I have not had snow since 1985 and the ac does help defrost by removing high humidity and allowing some to drip out the evap case.

^^ True, but that's defogging, not necessarily defrosting.

There are certainly situations where the A/C is useful, but that's usually when it's 55-65° and raining. That's typically when the windshield will fog up and using heat will be effective, but really uncomfortable. That situation is rare and doesn't happen from November through March, so I pull the relay. When I put the switch in I'll be able to make the decision and run the compressor when-needed.

I went to pull the A/C fuse in the footwell and it completely disables the entire HVAC system. Pull the one under the hood however and it defeats it.

Ummmm.....you guys know there is refrigerant oil in the a/c line with the refrigerant?
You are supposed to run the a/c system once in a while to distribute the oil so you don't have problems....like rust internally in the lines or the oil not being distributed in the a/c compressor? The oil also keeps the o-rings pliable and not harden and split.

Check the owner's manual, but I believe once a week is what is stated. (This goes for all cars not just Mazda). I wouldn't disconnect the entire system for a season. A cut-out switch is the better method I think.

You are not going to get rust in the lines. Read up about how A/C systems work because it's pretty clear you know very little about them. If there is even the remotest possibility of rust, your A/C has already failed.

Having the A/C come on with the heat (heat!) is a recent change, like in the last ten years. The RX-8 is the first car I've owned that does it, and it's stupid. It has nothing to do with lubricating anything, and everything to do with too many lawyers and not enough lions to feed them too.

Leaving the A/C off for an entire season will not shorten the life of a properly-designed A/C system. At least it didn't in the last dozen cars I've owned including the 17 year-old FD RX-7 I still own. None of those cars turned on the A/C with the heat. My brand-new truck doesn't so it will go entire seasons without the A/C running.

Man I love car forums. People tell you all the time to read your owners manual, but if you follow it, then someone tell you your doing it wrong! Nice!

And I guess moisture never gets in any a/c systems either? That's why when you do a/c work you first evacuate the refrigerant then you pull a vacuum on it with a vacuum pump for about 10 minutes to remove any moisture that may be present?

And I guess it is recommended once a month to run your system. But if you don't want to that's up to you since your the a/c expert and it's your car. I just gave the OP my own opinion and Mazdas.

https://www.rx8club.com/attachment.p...1&d=1291311737

As stated above. Moisture in an a/c system can and will TRASH the system. And you pull a vacuum after repairing the system. This remove all air and boils off and removes any moisture that entered the system while it was opened up for repair. Air and moisture do not work well in an a/c system.

thats why he said pull the RELAY, not the fuse. the RELAY is under the hood and what you found to work.

You pull vaccum on the system during service to remove moisture that had ALREADY entered the system(thus the reason for servicing) and/or to remove any moisture you introduced with the process of servicing. You should understand what your points are before you use them to debate.

He's not wrong about that. With an intact and functional HVAC system there's no fear of corrosion in any of the refrigerant stuffs.

RTFM is a valid and often needed statement, but you before you can use that as grounds to debate with, you need to be smart enough to understand that there is often info in those things that's excessive, stupid, or even plain wrong. They reccomend running it to cover their ass for the most remote possibility that something could dryrot or seize.

If you're not too stubborn to care, my HVAC system went ~2 years straight at one point without EVER being turned on, heat, A/C, nothing... and no issues to date with using it(that was about 2-3 years ago)

I'm going to just refer back to the original post:


Beefy98,

In my opinion and, I'm not an a/c expert, I recommend you install a cut out switch for your a/c clutch to have the system do what you want. As for me, I don't really mind the way the a/c systems works these days as it seems most cars are built this way anyhow and it doesn't seem like it is going to ever change back. (that the defroster position automatically turns on the air conditioning). Eventually in the next few years, as more cars are going to come standard with automatic climate control systems, the car will have more control than a driver will. I'm am not sure it has started already in a few luxury vehicles, but I bet they probably don't even have an "a/c request" button, you just set a temperature and the car does the rest. The Mazda with auto climate control automatically uses the air conditioning, the only way to turn force it not too is to go back to manual control.

As for me, I sometimes run my air conditioner for a little bit, even in the cold weather months, following the recommendations of several different owners manuals I have read in the past.

And you have a Series II correct? If you PM me, I think I can get you a wiring diagram for the a/c system if it would help with what your doing.

ahh ppl always r trying to mess with something never gets old haha

messing with stuff is in our nature. doing things the hard way out of ignorance just sucks though
:mchase:

Hence the presence of desiccant material and a part called a receiver/drier in ANY and ALL refrigeration systems. Moisture will leach into an A/C system over time. It is highly advisable to run your a/c system BRIEFLY throughout the winter. I've always found that drivers whose cars don't do this automatically tend to have more problems in the spring when they want to use their a/c for the first time. The leaks that i find more commonly are at the soft seals and o-rings in the system. These seals rely on periodic lubrication to maintain suppleness and resist shrinkage, cracking, and failure. This is often where the moisture gains entry into the system... so... instead of deleting the function of something you have limited understanding of its purpose, just learn to live with it - you aren't making it "better." This has NOTHING to do with bean counters or lawyers. It's actually designed by engineers who have typically very advanced degrees in their respective fields and often a number of years of practical application. In short, they know what they are doing!

We can argue adnauseum about why one type of system is engineered one way and why one is engineered another and why or why not it is a good idea to change from one method of operation to another. My point is that perhaps more than what you think has been thought of and your actions may result in less than desired outcomes.

Ray

Ray

As for the original question, has anyone figured this out? On my Xterra I just had to cut a wire, was nice and easy, but on the 8, I find it annoying. Like today it was a rainy day and would just need some air to blow across the windshield cause it was fogging up because it was raining (and quite hard) out, and I would perfer to not lose power and fuel economy for nothing. In general, probably a habbit/preference I developped from when I started to drive when cars werent like this ('90 626 and my Mx3), but I tend to perfer to drive with the air up on defrost rather than the vents since I dont like the direct air blowing on me, but I like some airflow in the cabin