ZOOOM

Has anybody noticed the heat build-up around the the driver's cabin especially when the air is turned off and the fresh air passage is open meaning (no recirculating) I noticed that last night while it was kind of cool outside 55F normaly on other cars you get almost the same outside air temerature from the vents I am thinking it is because the higher temperature the rotary engine runs on. I didn't like that but I still love the car:D

OmegaBob

Hey, just a thought....

You think the problem with the AC might have to do with the fact that Mazda might have included that cabin air filter with these cars? Hence the reason why the air flow seems to be blocked.

Can anyone who has their car check to see:
1 - where the filter is at (my guess, behind the glove box)
2 - is there a filter in there

Rx4FUN

When I test drove an 8 last week in Phoenix (only 108 that day), the AC was fair. About the same as my Z28. I think both cars have the same issue. The engine sits far enough back that part of it actually sits right under the dash and all the AC ducting. As the engine heats up the heat rises and the area under the dash gets very warm. The cooled air from the AC condenser has to make its way through this heated duct work before entering the cabin. While the compressor is running the air is cool (although not as cool as some other cars), but when the compressor cycles off, the air is then heated under the dash before exiting into the interior. I get a nice blast of hot air in my Z under hard acceleration when the compressor cycles off. It's even worse in the Z after it sits in the sun for a while (big windshield and big dash).

I'm also guessing that the temperature pickup in the 8 for the AC compressor cycling is located fairly close to the condenser and doesn't take into account the additional heating that happens further along in the duct work. Thus accounting for the large variation in temperatures.

Just a guess...

Boozehound

Everybody's saying the compressor cycles... why should it be cycling at all under max cold contions? There's no auto climate control, the driver adjusts temp and fan speed, and I would assume at full cold conditions with full fan, and recirc, it shouldn't cycle off period.

I suppose there could be a cabin mounted thermocouple that lets the ECM know how cold/hot the cabin is and engages/disengages the compressor clutch accodingly. Which is pretty much all an automatic climate control does. If this is the case, I hope there's a fix. Either give us an automated system, or full control - not something where the user gets overrided periodically for conditions not driven by performance/ engine use.

Rx4FUN

You don't need to have auto climate control for the compressor to cycle. The AC system in a car needs to keep the evaporator from freezing otherwise it will become a block of ice from condensation and no air will be able to flow through it. There are two ways to control the minimum temperature of the evaporator, either cycle the compressor, or cylcle the suction of the compressor on the evaporator. I'm not sure which method is used by the RX-8.

Here is a link that explains how it works:

http://www.delanet.com/~pparish/ac_works.htm

91vert

I'm really wondering if there is some design issue with Mazda A/C when it comes to trying to mix the air through the dash vents and floor vents.

I have a 99 Millenia S, and I have noticed on that car that if I have the air coming out of the dash vents and the floor vents that it doesn't cool as well as just having it coming out of the dash vents only. Air actually does come out of the floor vents, but very little.....barely noticable unless you have the blower cranked.

I hate the auto climate control, so I never use it. When it is 90+ here in St. Louis (and it is usually humid as hell here), my Millenia A/C works best on recirc and the blower on the second speed. It blows ice cold and usually cools the car down quickly. I hear (never feel) the compressor cycle on and off sitting in traffic with everything set this way. Usually cycles on and off in about 30 second intervals.

I hope my 8 A/C will at least work just as well as the current ride. If not, I am going to be very disappointed.

JSG

I'm glad other people are finding the A/C annoying - I thought it was just me. After almost 3 months with the car the A/C is my #1 complaint. For me it's not the cycling on and off but the actual capacity of the unit being too low. This weekend I was driving for 2 hours with the air on recirc & desired temperature at 24C. It was 30C ish outside (but 38-40 on the ambient sensor) and the fan never went below 5 out of the 6 speed range. There has to be something up with that. The air coming out is cold if you direct it at your body but the unit never manages to cool the cabin.

If you shut the side vents you get lots more air out of the centre console. If you use the floor setting it does reduce things considerably. On that setting air also goes to the back from outlets under the front seats.

TybeeRX-8

I suppose this should concern me, but I'll have see for myself.
In my Miata, the ac seems to work fine when using the dash vents and somewhat less when using both dash and floor vents. I usually leave it set on #3 fan speed and slightly off maximum cold. Of course, when it's really hot and the top is up, I use recirculate to cool things down. When driving, it will blow warm air if the pedal is on the floor around 5k rpm. You can feel the clutch disengage and once I back off to cruise, it cools again.

FredB

After hear owner say that the blower sends out very warm air (AC off) even on cool day I'm going to propose this theory about at least part of what's going on.

When using AC the compressor is going to go off and on in response to your setting and what the sensor says the temperature is. I don't know where that sensor is but that may be part of the issue. The other is that there's just too much heat around all the ducting for the AC as so as soon as the compressor shuts off the temperature of the delivered air rapidly rises. It increases in any vehicle but at a much slower rate. The RX-8 like the RX-7 places the engine and transmission closer to the driver than other vehicles. In fact I think they moved engine further back on the RX-8 than the RX-7 by an inch or so. All of this is supported by the fact that the cosole seems to be getting somewhat warm. So in addition there is a large heat load on this AC as well as the delivered air being heated by its surroundings.

I don't know if this explains the entire issue but maybe part of it. Maybe the temperature control accuracy is also not matched very well to this environment and the AC stays off too long, allowing the air temperature to rise too quickly. Maybe some sort of radiant barrier or insulation might help. Lastly it could be a compressor gas charging issue as well although I doubt that all cars would suffer from this unless they just got it wrong. I'm sure Mazda will have to come up with some fix for this if enough complain about it. But a lot of this makes sense if you consider that you get warm air when running on a cool day without AC. The RX-7 also created a lot of heat but as I remember, the AC more than kept up with it. Just a theory for now. What do others think?

Urchin

Thanks RX4Fun. From the link you posted, the thermostatic switch cycles the compressor off when the evaporator gets too cold.

Question: Is it possible to adjust the switch to control the temparture at which the compressor cycles. Any A/C technicians out there? 40 degrees or less would be good. My '88 Vert cycles off in the low 30's, and never have had problem with ice on the evaporator.

And please do not take this as a gripe, love the car. The A/C is just an observation that might make the car even more fun (110 today in Phoenix.)

bassik277

I live in Los Angeles, where it gets pretty damn hot, and i was wondering to those who have the car, is the air-conditioning so poor that it leaves the cabin unbearably hot? Or is everybody just exagerating e little bit

DisneyDestroyer

I was driving through downtown LA, SFValley, and SCValley last weekend in the middle of the day (90+ in all three) and was never uncomfortable due to lacking AC. It did seem to improve over the course of the few hundred miles I drove that weekend.

At the beginning of ownership I was keeping it at notch 2 or 3 (out of 4), but now I'm fine at 1 almost all the time.

Good Duck

It all depends on personal preference really.

Today at midday, it was about 93+ outside. I had to turn the A/C on to full blast for the first 10 minutes. After that, I left the fan setting at "2". That was enough to keep the cabin relatively cool. It seems to have the same performance as my Civic. Although, the only gripe I have is the fan speed setting needs to be more variable. I'm used to my Civic fan that function more like a rheostat rather than just 4 speeds.

Cylo

I work in the SF valley... it is uncomfortable when at idle, but when cruising, it cools down quite a bit.

Master Phu

I live in Reno where the weather changes every 5 minutes or so. Two days ago it was 103F and i kept the AC on 3, recirculating with only the dash vents blowing directly at me and I was fine even at idle. I really don't care whether the cabin is cool or not as long as I'm cool so that might be why I can bear the AC better than most here.

8_wannabe

I don't like putting the fan above 2 'cause it gets noisy, so that probably contributes to my problem. At settings 1 or 2 it struggles to keep the cabin cool if outside temp is above maybe 80 or so. If I set it to blow on feet and face, it goes 95% to feet and 5% to face; very unsatisfactory. Therefore, I leave it on face only. With no pax, I shut the right-side vent and increase my airflow. And during all the above, the compressor cycles on and off, so air temp from vents fluctuates widely.

I'd say it's a slight disappointment but in no way reduces my satisfaction with the car. Everything else is so wonderful that the a/c problems fade into the woodwork. I'm just puzzled as to why this is an issue at all. Clearly, Mazda could have done better and I don't know why they didn't. I've got 540 miles on the car. If it improves with age I oughta be seeing that pretty soon. I'll let you know. Please don't let this be the deciding factor in a buy/no buy decision. I think at worse it's just a minor annoyance; doesn't seem to bother my son at all in the same car.