The correct technique to cool the car with the ac (from my Honda CRX owners manual in the US, and it worked well for me in Alabama) is to:

Open window a little.
Set to fresh air.
Run fan at max and switch on ac.
Wait a couple of minutes, close window, set to recirculation, turn down fan.
Should be icy cold (on coldest setting...) if the refridgerant is ok.

However, I found the ac in a 96 M-edition I drove for a while in the US nowhere near as effective as my 91 Honda, so it maybe that the Mazda one isn't that great. My Roadster cools quite well here, but doesn't seem really cold. Plenty of refridgerant in the system though. (11/99)

Yes, you do need to run the a/c regularly even during the winter. But (sorry to contradict again ) it's not to do with the belts as the a/c belt turns all the time. It's to stop the compressor seizing - the compressor uses an electric clutch and even though the pulley turns constantly the compressor itself can be spun/stopped under ECU control.

BTW I'm also told that you should turn off the a/c but leave the fan running a few minutes before stopping. I'm told this is to dry out the evaporator and stop it getting mouldy, but I really wouldn't like to guess whether this is for real or not. (4/00)

There's a rubber drain hose which runs from the evaporator down to outside (comes out by the gearbox - at least on RHD cars) to drain water condensed from the air. You'll find it attached to the corner of the evaporator under the glove box. I'm not familiar with LHD layout - on a RHD car it is in the right hand corner close to the transmission tunnel. I assume the evaporator is not "handed" so I would think that on your car it will be somewhere in the middle between the transmission tunnel and the right hand side of the car. If the evaporator is handed it will be close to the forward end of the transmission tunnel.

My guess is that this pipe has become disconnected, or maybe perished or hardened so that the joint leaks. Look under the glove box, close to the bulkhead (firewall). The pipe runs forward slightly, then turns down. Replace the pipe, or seal the joint.

The aircon on 94-on cars is not fantastic due to use of "environmentally friendly" R-134a refrigerant rather than more efficient R-12 used previously. It should still cool the air to something like 15-20 deg C below ambient air temperature. The system may need a recharge - job for an aircon specialist - should be plenty in your part of the world! (5/00)

Hmmm...often wondered this....

Are we the only ones with a Roadster that definitely "reacts" whenever the AirCon kicks in? On initial switch on we *do* get a momentary rev drop, followed by pick up. More disconcerting (although probably entirely in keeping with the above!) is that it does it regularly thereafter i.e. you'll be driving along at 60 mph with AirCon on - then you'll hear it "spit", the accelerator pedal "twitches", momentary power drop and then it gets back to normal. As I say, somehow the initial "blip" seems expected but the later ones (typically when up to speed) are a bit worrying. (5/00)

When you select aircon, you should experience two things.

1. The engine revs should increase slightly - this is called `idle up', and is to compensate for the extra drag on the aircon compressor.

2. You should very soon start to shiver - this is because when it works, the aircon works really well!

If you don't experience both of these, I would suspect that the gas has leaked out, (it happens gradually over a period of years). You then need to look around for someone who services aircon, but beware! A great number of garages still think that aircon is a luxury item, and consequently charge luxury prices for it. Ask around a bit - you should hopefully find someone who won't try to rip you off, (in this country?!!). I went to an agricultural engineering company and they did mine for about half the price the so called `specialists' were quoting. Well worth following that path, as most new tractors have aircon these days! (5/00)

Check the temperature of the air coming from the vents with the aircon on after 5 mins or so. It should be 15-20 deg C below ambient air temp on a warm day.

The second (right hand) radiator fan should run at all times with the aircon on. There is a refrigerant sight glass - look down through the hole, rhs of the car, in front of the radiator. With engine running and aircon on, get someone to switch the aircon off. The sight glass should show refrigerant that foams, then clears.

It may need a recharge - it may be a different problem. Poor Graeme had no equipment fitted - it doesn't get much worse than that! (5/00)

1) Make sure the fan is turned on. But ISTR the blue light doesn't come on unless the fan is on.

2) With the a/c off open the bonnet. Beneath the power steering pump on the right hand side is the air conditioning compressor. With the a/c off the pulley turns but a clutch prevents the compressor turning.

3) Turn on the a/c (best to get someone else to do it) and you should see (and hear) the compressor start turning. If it doesn't it's almost certain you have lost some of all of your gas. (5/00)

nothing to worry about

There's a thermostat in the evaporator (the bit behind the dash that cools the air). Interestingly if this fails either 1) You get no cooling or 2) It cools so much you get ice forming in the evaporator. The latter conditions gets you VERY cold air for a while and then nothing.

it's quite a sexy whine

Never noticed any whine from ours. Not even with the gonzo belt a supercharger requires. (5/00)

I¹m no expert with the Air Con system, but when I turn the Air Con on in my ¹89 Eunos, I do get a momentary drop in engine speed which is immediately compensated for.

Try putting the fan on full blast with the Air Con switch depressed, you should get cold air coming out pretty quickly.

Also check that the compressor is actually being driven by the drive belt (bottom front left of the engine). Another check would be to look down in front of your radiator; there should be a cylindrical unit with a few metal pipes coming out of it. This will have a small circular glass ³window² on the top. With the engine running and the Air Con on (and the fan speed set to anything but OFF) you should be able to see some of the coolant/refrigerant being pumped through it.

As soon as the Air Con is turned off (you might need a friend for this bit!), you should see the refrigerant ³foam² for a short while. If not, it may need a recharge. Also, with the Air Con on, I think the second fan behind the radiator should come on. (5/00)

It's in a spray can. SP-22 Belt Dressing ("Prevents slippage. Prolongs Belt Life" "Maximum power transfer to Pumps, Fans, Steering, Alternators and Air Conditioners. Specially formulated for Rubber, Leather, Canvas and Fabric Belts. Contains no Rosin or Asphalt")

One of those things that you never knew you needed, but now you do, where do you get the stuff? I assume Motor Factors will carry it. I get mine at the odd auto jumble I go to once or twice a year. This SP-22 stuff is made (well, sold) by Sperex (0234 212571 (Bedford) - obviously an old can) I have seen other brands.

It instantly quietens any noise from a belt (I spray when it's running) so it must do something. (5/00)

Purchased today from local independent (read decent) motor factors: Comma Belt Dressing 'Reduces slippage and will extent belt life.Eliminates irritating belt squeal, Not harmful to canvas, leather or rubber.' says so on the can. shake and spray. £4 Sounds like the same stuff, but easier to come by.

PS. Sperex are no longer in the Bedford phone book (5/00)

I hardly ever use it

Just to clear the car when it mists up in the rain ! It's nice to blast yourself with freezing cold air when you're stuck in a traffic jam in the sun (roof down of course) but it does effect the engine idle and performance. (5/00)

What happens if you need to re gas the system? The old gas it came with is now illegal to use(R12)

For new installations yes, but to me knowledge refilling old systems is fine.

and to use the new gas, (R134a) you need to flush the system and change quite a few components. Anyone done this?

You need to drain out all of the oil (probably involves removing the compressor) and change the O-rings. It's then refilled with new oil and new gas. Some manufacturers don't approve their older compressors etc. for anything other than R12. R12 is bad, but unless you're leaving it's not doing too much harm. (5/00)

Has anyone else had the misfortune to suffer from the disease caused by spores coming from infected air-conditioning units?

Our own experience has been very upsetting. Having been unable to put up with the slightly odd smell of the unit in our imported four-year-old Eunos, we had the thing taken apart, the condenser removed and thoroughly scrubbed with various substances including Dettol and Milton, and then pressure-washed . Obviously even this drastic treatment wasn't totally effective, or perhaps the fungus was located elsewhere in the system, as the subsequent problems proved.

Driving down to Cornwall on a blazing hot day, my wife and I had the air-con blowing hard into our faces all the way. We were both in excellent health and had not been in contact with anyone nursing a cold, tonsillitis and so on. The day after we arrived, we both developed painfully sore throats and hacking coughs. As we were getting worse, we decided to return after a couple of days, rather than risk a long drive when really unwell.

Back at home, I felt really ill that weekend, and spent a night coughing so hard that I was gasping for breath. With the doctor's surgery closed, I had to visit hospital, where they found no infection and were unable to explain the problems. My own GP found the same, but when there was no improvement he said it could only be an allergic reaction for which he prescribed antihistamines.

The condition lasted a full month before I was back to normal, and it was only during this recovery period that I was able to research the problem and discover what had caused it.

Apparently it is caused by spores from a fungus that develops within the cooling system, both towards the bottom of the condenser and in the other passages, and they attack the throat and lungs in a way very similar to "Farmer's Lung" which comes from inhaling musty hay and is quite a serious condition. Thinking the problem to have been a one-off caused by the excessive use of the air-con on the first occasion, and knowing that the system needs to be used regularly to keep the seals lubricated, I turned it on for just five minutes at the beginning of this month, with the windows open and the output directed to the floor. The reaction was almost immediate, and - although less severe - the cough and sore throat returned.

It's not as if I have some unusual allergy, as my wife (the fittest person I know!) had the identical symptoms on the first occasion (I was driving alone during the recent repeat).

I've seen an ad in the Sunday papers for a franchise operation that claims to be able to sterilise the unit for around 60. I have my doubts about the effectiveness of this. When I first bought the car, the air-con specialist first tried injecting an expensive US-made sterilising aerosol into the unit in situ, which had no effect whatever. To be fair to him, he did point out that the Mazda (Eunos) unit was very difficult to treat in this way, as it was hard to reach the central part of the condenser from either end.

Have others had this problem - maybe only a sore throat which you may have dismissed as coincidence until now? Has anyone successfully cured the growth of this obnoxious (and, I must say, almost invisible) fungus? (10/00)

I'm going to talk shop (Microbiologist) for a bit.

The nasty disease associated with airconditioning systems is Legionella, but thats only found in building aircon, especially those with a roof mounted cooling tower. The legionella bacteria thrives in the humid air.

Fungal-spore associated respiratory tract problems are generally allergic-reactions. Fungal throat infections are generally (though not always) only a problem in people with weak immune systems (elderly, immuno-compromised, immuno-supprersed (ie. on medication)). The attempts at cleaning the system with chemicals may well exacerbate problems, as you're unlikely to get the system dry. It true that if an allergy had developed, its unlikely both you and your wife would both develop it (though you have both been exposed to whatever the system was kicking out for some time). The antihistamines prescribed help relax the lung lining. A reaction to a caustic chemical, such as that found in cleaning agents, would have a similar effect in irritating the lung tissue, leading to some minor tissue damage that takes a little while to heal. The symptons would be similar to an allergic attack (indeed, part of the response is through an immune response). I'm surprised corticalsteroids weren't also prescribed to ease your condition

Silly question, but do you set the aircon to recirculate or fresh air? Recirculate setting may succeed only in recycling spores/dust from your carpets/mats.

I thought Farmer's Lung is more a problem with persistant longterm exposure. You don't get it just through walking in a hay field.

If you think its a problem with Fungal spores, Charlie the steriliser isn't going to help. These attempts to "sterilise" a system sound a bit quackish. If you think its a persistant problem, and damaging to your health, ask your GP for a speciman bottle (plastic, sterile until opened). With a cotton bud, take a swab of the inside of the air vent. Your doctor should be able to forward it on to the local Public Health lab for you for examination.

Try running the car (but don't sit in it), roof down, on fresh air, on hot (not cold), aircon on, max fan, for 10-15 minutes. That'll dry the system out thoroughly, and eject any really loose material, and allow noxious material to disperse properly. Take your mats out, and thoroughly clean, steam clean the carpets. I'd be cautious to come to a conclusion on what caused your problems based on your own research.

There are many explanations. Plenty of MX5s suffer the mould roof saga, and there aren't any people reporting problems from this. (I don't, and I'm an asthmatic) (10/00)

we had the thing taken apart, the condenser removed and thoroughly scrubbed with various substances including Dettol and Milton, and then pressure-washed

Totally pointless. The condenser does not interact with the air in the cabin - it sits in front of the radiator and cools and condenses the hot gas before it's returned via the compressor. The gas and the air do not mix. It's the evaporator that's behind the glovebox that you need to attack. (11/00)

Have you come across this problem before?

Someone said his evaporator started to smell, so he had to spray it with detox, or something. I always turn off the a/c a few minutes before stopping to try and dry out the evaporator, particularly if the car is going to be sat for a few days. Ever thought maybe it's all the sterilising stuff that's irritating your throat? (11/00)

I hadn't expected quite such an authoritative reply as that from the Microbiologist, and I'm most grateful for these comments.

I had hoped that two days of full-blast air-con in really hot weather (yes, with fresh air input) would have thoroughly dried out the system. I am even in the habit of always turning off the air-con a mile or two before the end of a journey, to dry out the condenser and avoid the usual puddle under the car. But I had wondered if it was possible to use a combination of heater and air-con, with the car empty, to dry out the system on a regular basis - so I'll do this; as you say, residual chemicals could be the problem and the more the system gets a good blow-through, the better.

I'll also follow the advice to thoroughly clean the carpets, although I have to say that they haven't been giving any problems with normal heating or fan use - only when the air-con is switched on. And if I can persuade my GP to send a swab for analysis, I'll report back with the findings. As you say, the cause may be something quite different, and it's easy to jump to a false conclusion. Finally, a small tip that some may find helpful.

In case of any trace of stale-car odour, you can keep a small Clip-On brand deodoriser (Halfords etc) into the ashtray and push it right to the back. Then you can control its effect by opening and shutting the sliding lid. And no, I'm not allergic to deodorisers ;-) (11/00)