JMD RX-8

I'm curious as to whether the A/C compressor is running when the airflow is split between defrost and lower. On my honda, it doesn't run. But I think I may hear it kick on in my 8. I am aware that it runs in defrost mode, but there's still no light or indication beyond simply hearing it kick on. When you cycle through the different airflows, does it automatically turn on and off? I'd like to run it as little as possible to save gas, reduce load and wear, etc.

zoom44

it runs anytime you have floor or a combo of floor and something else selected even if the light doesnt show it is. but it shuts off when you go over 65% of wot. so if you want to have it off when you have selected floor KEEP YOUR FOOT IN IT

Brandon

Yeah it probably is running if any defrost mode is picked. I would think it's running on the Honda as well because the main way the defrost works is by drying the air. In my previous car (also a Honda), I could select defrost and it would automatically light up the A/C button. I could then turn the A/C off but keep the air coming out the vents at the windshield. But if I did that, it would actually fog up worse if it was at all humid.

r0tor

iTrader: (1)

hmm... didn't realize the compressor kick on in bi-level and the foot modes. Thats kinda annoying.

rodmeister

That explains the cycling sensation of the engine on idle when I have the air to the floor. I suspected the A/C was cycling but couldn't believe Mazda would be so stupid. Where did you learn this?

zoom44

one of the many many reports and/or articles i have read since first starting to research the car nigh on 3(or is it 4 now?) years ago. also i think its in the manual whenever the defroster is on the ac is on and whenever floor is selected the defroster is on. no matter what the little icons are telling you. if it didnt, because of the position of the engine in relation to the ducts and the windshield, whenever you switched it to floor your windshield would fog over.

r0tor

iTrader: (1)

hmm... i wonder why my car fogs up something fierce when I have it on bi-level, I would thinking the AC should be drying the air out enough like the defroster

rx8cited

I wish Mazda used the same logic as Honda for the defroster A/C control. It's annoying that the A/C light does not come on and that you cannot override and turn the A/C off in certain vent positions.

Chrisbert

I think it is in the User Manual.

Ninja

Yes, it is in the owners manual.

rodmeister

Okay, okay ... it's in the driver's manual.

This may have implications for my gas mileage since I use bi-level and low-level airflow most of the time. I'll see if I can I can improve my 16mpg.

RotaryNoob

OMG, maybe my mileage will get better also. MAYBE THIS IS WHERE THE LOST GAS MILEAGE WENT!!!!!! :D

downshift

I don't think the dashboard-floor mode would turn on the compressor, as indicated on page 6-8 on the manual. Unless this was changed after the L/M flashes. If what you said is indeed true, I'd be happy to know why I got shitty mileage lately.

rodmeister

Rather than rely on the manual, which might be incorrect, I investigated the A/C compressor runtimes directly by ear and tach. - First I familiarized myself to the sound of the A/C compressor while idling at stop signs. I could hear a solenoid or something "clunk" whenever I selected A/C. At the same time the tach would blip slightly momentarily. I also could hear the engine take on a deeper tone when the compressor cycled every couple minutes with all the previous sounds and tach indication. - Then I selected the air-circulation modes. With The A/C off, I did not detect a "clunk" or cycling on the dash-only mode or regular dash/floor mode. All other air modes, including floor-only mode made the characteristic sounds of cycling. - I'm disapointed with the floor-only mode cycling the compressor, since I use it a lot, because I dislike having hot air blown at my face and chest. On cool nights I like to drive with open windows and hot air blowing at my feet. Since I use the floor-only mode almost 50% of the time, it must be hurting my gas mileage. I'll avoid the compressor modes and check my mileage

StealthTL

iTrader: (1)

If you want to check the 'non-a/c' mileage without giving up your hot feet, you can pull the fuse to the a/c clutch.

The clutch has its own fuse, 10 amp, bottom of the engine compartment fuse box. Then you know for sure, and can generate some real comparison figures, yet still enjoy (most of) the modes you want.

S

RotaMotion

(Rant On)
It’s been cold here late…well by California standards…30s in the morning. It is seriously Pi$$ing me off having the A/C turn on when I’m trying to warm up the interior of a cold car. If I put the heater on High and on the Floor vents—Hey, my feet get cold J I expect un Air Conditioned air. I mean, the car is warming up and I’m trying to get some HEAT going.

This is absurd! This is a gas waster and feet cooler.

Also, having the AC run all the time creates condensation in the AC evaporator (it’s like a little radiator under the dash that cools instead of heats). That leads to the musty dash vent smell. Yes, I can blow things out with the dash vents before I shut off the car, but this is just stupid after running the car with the floor heater on.

Are there some Electrical Engineers that could help with where to cut and wire in a switch? Can some Common Sense be "Flashed" into whatever computer controls the AC?

Also, I think I’m going to embark on a Mazda Technical Crusade. People who buy sports cars like to have control of their "driving experience" Here's to Death or victory…

BTW, I think this is a result of Fords influence on Mazda. Ever tried to control the AC on a Ford…

Nubo

Lol, I wouldn't be surprised. My wife came into the marriage with a Ford Escort, with the "automatic seat belt" that was always trying to decapitate me. Lame engineering. The little hairs on the back of my neck stand up just thinking about it.

dmp

Very crappy information - I'm annoyed as well at the 'AC on all the time' policy for this car.

Looks like no more feet&dash venting for me. :-/

khtm

From what I've read...it's not JUST feet&dash venting, it's also dash venting alone...?

Please correct me if I'm wrong, anyone.

dmp

Right... both of those options are off limits now. Lame. Very Lame.

rx8cited

"Feet&dash venting" as you say or "dashboard and floor vents" should not cause the compressor to come on unless the A/C button is depressed to turn the A/C light on.

The "A/C down your throat, like it or not" happens if you select "defroster and floor vents", "defroster vents", or "floor vents".

For "dashboard vents" or "dashboard and floor vents", A/C should only be on if you pushed the A/C button to on.

dmp

er?

Dash + Floor = No A/C unless AC button is depressed

Dash = A/C on

Floor = A/C on

?

that right?

Nubo

As far as I know, "dash vents only" is the ONLY non-AC setting. I guess I could just check the car....

dmp

I get no change in Idle or sound when I switch thru the settings...including when I hit the A/C button.

Atacdad

I'm 99.9% sure I hear the compressor kick on in floor only mode as well. I am not sure what it does for bi-level (vent/floor)....anyone know for certain?