Air conditioning, NDs, and the Southeast US
 

A serious question:

I've never really used aircon much. My first two Miatas didn't even have it. My '04 does, but until last month I lived in NY and Chicago, where it's just not relevant.

Now I find myself in the swampy Southeast. And it's a whole different story.

Took the car to a shop for an evec and recharge. Low side was 5 PSI (basically empty) but that's after 13 years of total neglect. Had it recharged and it's still holding pressure.

And it still sucks.

I mean, I feel cold air coming out, but it's not as though the interior of the NB is exactly well-insulated to begin with, nor the performance of the aircon system especially high.

So I ask the following, of people specifically who live where it's 90° and 95% humidity as you're reading this: Does the aircon on the ND still suck as much as the NA / NB, or did Mazda finally make this a priority?

Go to the stealership and feel it yourself, because IMHO this is a very subjective question and most "Miata guys" will tell you theirs works perfect, which for you (and me) means it's barely blowing any sort of cool air at all, and you get to work with huge pit stains and are "that guy no one wants to sit next to" in a meeting.

ND is worse than NB in my experience, assuming NB is working correctly (evaporation clean, condenser in good shape, charged correctly, fans work, etc etc). I test drove a ND and the a/c in that car was terrible, to the point I called back and asked if it was defective in that car and was told it was not defective, that's just how it is. And I didn't order one, poor a/c being one of the reasons why.

FWIW you can put a temp gauge in the vents and quickly see how cold it's blowing air, if it's not around 40*F when rolling 20mph or higher, something is off. At idle it will creep up around 50*F on a 95*F day, but once you are moving it gets into the low 40s in about 30-40 seconds.

Even in my MINI on a humid 90 degree day, it starts to get swampy inside when rolling slowly. The system will kick off and blow juicy air for a while if it gets too hot. This is even with the recirculation on.

If it blows 50 degrees when sitting still you will hate life.

I supplemented my stock wiring with a 6-gauge wire from the alternator to the battery and from the alternator to the fuse block. Each one was fused, of course. I also added an additional six gauge ground wire to the frame. I considered supplying the hot side of the fan relays directly from the battery with a new larger gauge wire but found the other changes to be adequate. I know that air conditioner performance is often times related to the condenser's ability to shed heat. The additional wiring has improved the performance of the Interior blower fan as well but everything is still marginal.

Quality window tint will help because it will prevent the ultraviolet radiation from entering the cabin. Reflective adhesive-backed foam on the transmission tunnel inside and out made a significant difference.

Joe, is there an easy way to increase the speed or volume a of air moved by the blower fan? A way to step up the voltage to 18 or something on that one circuit?

I found the NC to have acceptable AC performance and I live in OK. I'm surprised the ND is worse than the NC.

It's not uncommon in OK in July/August to have 100° temps and 80+ humidity. It may get to an ultimate higher temp in the southwest or more humid in the SE.............but it gets hot here early and stays all day.

We set the record for average temp for a year just a few years ago.............IE at 6am it can still be 85-90 with 60+ humidity.

The fan is clean and turning well.

The 134a was evacuated and recharged a month ago.

It just seems that the system as a whole was designed neither to move a large volume or air, nor to cool that air effectively, nor such that the interior of the car is well-insulated from the outside.

You know, all the things that I didn't give a shit about and basically scoffed at when living in SoCal. :D

ITT: we discuss turbocharging the A/C :)

Wonder what it'd take to hang the compressor from a Suburban on the side of the block... It's not like I really *need* power steering. ;)

:inout: dont have this issue in my MB.

For some reason, I don't seem to be able to give you an infraction for this...

until your "seat computers" go out right as the warranty expired and you gotta get em replaced for a measly 3 grand :giggle:
chump change for a MB owner amirite?
but really Joe, most luxo-cars of modern years have AC through the seats. game changer

Normal temps here this time of the year are anywhere from 98 to 108, so I feel you. It is not a matter of how much air the fan moves either; if you move air too fast through the evaporator, you do not allow sufficient interaction for it to cool down enough. I believe the only reasonable thing to do would be trans tunnel insulation and good quality window tint in an attempt to block (as much as possible) heat from coming in.

pretty sure this has been proven to be a false theory

Also check the heater door thingy, when you slide the temp selector to cold, it's supposed to block all the air from going through the heater core. That adjustment was slightly off on my NB when I bought it 11 years ago, and adjusting it to keep that door closed tight made a small difference in a/c performance. If vent temps are not 40*F at cruise, I'd check the evaporator for leaves/dirt/etc.

It has.

The same shit gets dredged up every time someone goes off about radiators and engine cooling. The short version is that up until some bizarre phenomenon line cavitation or non-laminar flow starts to happen, the more fluid you can pass across a heat exchanger per unit time, the greater the efficiency of heat transfer across the exchanger will be.


[QUOTE=patsmx5;1434199]Also check the heater door thingy, when you slide the temp selector to cold, it's supposed to block all the air from going through the heater core./QUOTE]
Does this require removal of the dashboard?

[QUOTE=Joe Perez;1434204]It has.

The same shit gets dredged up every time someone goes off about radiators and engine cooling. The short version is that up until some bizarre phenomenon line cavitation or non-laminar flow starts to happen, the more fluid you can pass across a heat exchanger per unit time, the greater the efficiency of heat transfer across the exchanger will be.


No, you can adjust it by looking under dashboard, and moving the slider to cold, and checking if the door is closed all the way. It's just a cable that snaps in place, so adjusting it is easy, unsnap, pull it tight, resnap into place.

Yes. Assuming the intake air is all the same temperature and the airflow is subsonic, moving it through faster means that you're just replacing air molecules that have been partially heated up by interacting with the heat exchanger with air molecules that are still at the ambient intake temperatures. Thus, better efficiency.

Do you have access to an AC manifold gauge set? They're pretty inexpensive at Harbor Freight, and will let you check if the compressor is operating properly.

--Ian

compound all the things!!

2 compressors, 2 fan blowers, 4 rad fans = nipples permanently hard