NB8B colder A/C tips

aviper4u · Postby **aviper4u** » Thu Dec 06, 2012 3:41 pm

As the ambient temps are increasing i'm looking to cool down the cabin.......

The system was checked a while back but i was always left thinking its not as cold as other cars which seems to be the generally accepted view on the mx5/miata forums etc.......

Anyone got any tips to increase our little battlers A/C efficiency?

Locutus · Postby **Locutus** » Thu Dec 06, 2012 9:27 pm

if you are getting 6C or less at your vents, there's not much else you can do to improve the AC - the thermostat will begin cycling the system on/off to prevent refrigerant from freezing in the AC lines. the factory spec is 6C or lower at up to 40C ambient (max fan, on recirc) so if you aren't getting those temps perhaps something in the system isn't up to scratch - i know mine definitely isn't...

did you check the condition of the 2 rubber boots at the gear stick when you put your stereo in? replace them if required.

the problem with the mx5 is a lack of heat insulation. the trans tunnel gets very warm due to the exhaust, and the inside of the soft top gets rather hot to the touch on a summer's day. while i was sweating away in the car last saturday i was pondering how effective it would be to lift the carpet and line the trans tunnel with a thin & lightweight layer of foam/foil insulation...

deviant · Postby **deviant** » Fri Dec 07, 2012 12:35 am

You can buy heat mat that is used in the tranny tunnel on race cars etc that should make a big difference.

Check this thread for vent issues: viewtopic.php?f=28&t=54596&hilit=vents

The NB8B A/C is pretty weak though...well I am not sure that it is weak as such it is just that the roof is a poor insulator against the outside heat.

Mr Morlock · Postby **Mr Morlock** » Fri Dec 07, 2012 12:18 pm

a/cs are not all equal and the NB is not brilliant. locutus looks like he knows so perhaps just get it rechecked to see if it delivering the right temp.

KevGoat · Postby **KevGoat** » Fri Dec 07, 2012 1:01 pm

I've just spent a fortune having my NA's aircon fixed recently and despite the air feeling very cold at the vent, around the cabin I don't find its all that great. The fans are very weak so the air just doesn't circulate much. Cold hands on the wheel, but the rest of me ain't that cold

But I guess its another of those compromises we have to accept with the type of vehicle they are.

I still laugh every time I recall from years ago a motoring writer, who's name escapes me, reviewed the MX5 convertible and complained about the car's lack of ventilation :lol:

samx5 · Postby **samx5** » Fri Dec 07, 2012 1:18 pm

My NB8A A/C was tested by Mazda recently and it was as good as they had seen with about 4 deg at the vents, however the fan doesn't seem to move much air (even though it is noisy) and as others have said the roof is a poor insulator, so it doesn't feel like its doing much. I've insulated my AC pipes under the bonnet with foam, the only thing I haven't tried yet is to replace or increase the thickness of the rubber bonnet seal at the back of the engine bay, which gets crushed over time and can apparently let heat through to the cowl panel from the engine bay. Mine looks squashed, so for minimal outlay it is worth the effort.

aviper4u · Postby **aviper4u** » Fri Dec 07, 2012 3:55 pm

looks like will need to man up and live with it.............

so to check the vent temp what a/c setting im assuming recirculate, cold and fan speed two as anything higher makes alot of noise and not much more air

Locutus · Postby **Locutus** » Fri Dec 07, 2012 4:22 pm

NB8B service manual section 07-10-2 wrote:

Postby **NitroDann** » Fri Dec 07, 2012 4:41 pm

Start by replacing the blower motor filter so that the fan works, buy a hardtop, insulate the trans tunnel and HTFU.

Dann

deviant · Postby **deviant** » Fri Dec 07, 2012 4:54 pm

I find my car feels much cooler with the windows cracked an inch, a bit more noisy but without anywhere for air to escape to the fan seems to struggle to move air through the cabin.

Silvia · Postby **Silvia** » Fri Dec 07, 2012 5:19 pm

Heat from engine is a big factor. you should check the rubber strip seal under the hood in front of windscreen. Over the years it crushes down. :idea:

A cheap roll of door sealer stickyback 10mm foam stuck across the top of the seal works wonders....

Postby **NitroDann** » Fri Dec 07, 2012 5:29 pm

How is that going to get into the cabin?

Dann

Silvia · Postby **Silvia** » Fri Dec 07, 2012 6:06 pm

The hot air passes through and straight into the air intake vents behind it :roll:

KevGoat · Postby **KevGoat** » Fri Dec 07, 2012 7:28 pm

BTW also worth checking this thread posted up recently: viewtopic.php?f=28&t=54596

The warm air vent not closing off properly also affects aircon temp. Not sure if mainly for NA's but worth checking. Mine wasn't closing off properly so warm air was always entering the vents.

aviper4u · Postby **aviper4u** » Fri Dec 07, 2012 7:30 pm

Silvia wrote:The hot air passes through and straight into the air intake vents behind it

I believe should only affect air when it is not on recirculate..... when using a/c on hot day always use re circulate which should draw air from cabin only.

PS *locutus* if i read your original post it says max fan already hehehehehe :oops: