Air Conditioning Problem - Any Ideas?

[eclipse1501]

Ive got a 1991 Acura NSX which I bought from a company who first imported it into Gibraltar from the USA, so basically Iam not the original owner, and I have a problem with the AC running an intermitent fault.

The AC display on FULL AUTO will set no lower than 60 degrees, which Iam not sure is normal in itself, but the cold air (having been gased recently) still ocassionally only runs cold for a few mins. On other journeys it will run cold without a problem for 30 mins of more. A mechanic told me it could be the AC compressor "clutch" not engaging and not sending the cold gas around the system but Iam thinking if the head unit is faulty this might be the trouble.

Before I take my NSX to a Honda dealer in Gib or Spain I wanted to ask
a) if anybody could tell me does their NSX AC setting go lower than 60 degrees?
b)has anybody had a similar problem with their NSX AC?
c)Is the facia around the AC head unit easy enough to remove if I need to send the head unit away?

Iam thinking if the AC head unit display wont go lower than 60 degrees (when it possibly should) I might just be able to send it for reconditioning?
Thanks for any advice you might be able to give :rolleyes:

[simonprelude]

In the UK the aircon is in Centigrade and the lowest setting is 18C, which is 64.4F so I would guess that 60F will be the lowest setting.

It could be the clutch, compressor or you could have intermittant leaks.

There are a few people on here who have had problems with A/C they might be able to help.

[TheQuietOne]

Hello,

I have a problem with my AC too actually. I can hear / see the compressor working but the air isn't cold! I had it re-gassed last year and have done about 5,000 miles since then so I know it isn't over use! Your theory of the clutch not engaging is interesting - does anyone have a way I can see if that is the case on mine? It would make sense.

Anyway keep us posted with yours and I'll do likewise. I will be picking up a new compressor etc on eBay if one comes up, I know Luke just got one for less that £150 if I remember right!

Cheers, Matt.

[goldnsx]

I didn't have problems with my A/C so I can only tell what other people esp. on prime came across.

Low on freon can cause this phenomena, cold on one side, warm on the other. Same for time intervals. I'd check that first. It's not unusual for an older car to loose the freon within a very short time interval. A bigger leak (heater unit) can force it out within a few hours. Most NSX I know (91-92) have to fill it up on a yearly base because they loose half of it within this period.
CCU: If it hasn't been changed or reconditioned on your 91 I'd do that anyway as it will fail in the near future anyway. If that cures your actual problem I'd say it's a 50:50 chance but a good 'investment' for the future.
Clutch: It don't think it clutch-related as far as you describe: If the clutch catches you should hear the A/C compressor clearly and as the clutch is magnetic it won't go bad in a way of slipping like a drivetrain clutch.
Also watch out for blown fan fuses, not uncommon on NSX's. Easy task.

You can bring the car to the dealer but they will change every part of the A/C until they've 'fixed' it. :cool:

[Sudesh]

What about checking the Sun Sensor and ASPIRATOR [small fan at your handbrake] These also have something to do with controlling the temperature in your car. Recently I upgraded the centre console and forgot to re-connect the aspirator the results was the temperature would not work correctly. May be worth a try?

http://i77.photobucket.com/albums/j77/icongroup/13SL00_016_3.png

[eclipse1501]

Thanks very much indeed for the responses which Iam investigating. The last one about the sun sensor also reminded me about something I was told about the AC system (possibly) having air temp sensors in the front air intake/grill which should not be tampered with, obstructed or touched. I had some stonechips sprayed a while ago and wonder if these got contaminated in the process - but I might be clutching at straws. Whats most frustrating is that the AC is freezing cold on some journeys for ages then suddenly dies, only to come back on again when it feels like it.

When I had the AC gased again a week or so ago the garage said the gas in my '91 AC system may now be a technically illegal type anyway and suggested I might let them fit a new compressor and regas with "modern" coolant. Ive not got a problem spending money on my NSX (especially if it sorts out this wet patch Iam sitting in!!) but they weren't an authorised agent or even a Honda dealer so I passed on the offer for now until I got some more feedback from you guys. Thanks so far for all your help.

[eclipse1501]

Hello,

I have a problem with my AC too actually. I can hear / see the compressor working but the air isn't cold! I had it re-gassed last year and have done about 5,000 miles since then so I know it isn't over use! Your theory of the clutch not engaging is interesting - does anyone have a way I can see if that is the case on mine? It would make sense.

Anyway keep us posted with yours and I'll do likewise. I will be picking up a new compressor etc on eBay if one comes up, I know Luke just got one for less that £150 if I remember right!

Cheers, Matt.

The garage who recharged my AC pointed out that if you touch the aluminium pipe just above the spare wheel where the AC is recharged from, if you put your finger end right around the back of the AC filler connection if the gas level is ok that point on the pipe feels freezing cold regardless of any failure of the compressor/clutch. So far mine feels cold all the time which suggests "Ive got gas" (my wife is nodding at this thought) but I would be interested to do this test while the AC is playing up.:rolleyes:

[goldnsx]

There's no need to change the compressor while switching from R12 to R134.

[Midnight Blue]

[quote=TheQuietOne;45101]Hello,

I have a problem with my AC too actually. I can hear / see the compressor working but the air isn't cold! I had it re-gassed last year and have done about 5,000 miles since then so I know it isn't over use!

Hi,

Air conds need to be used regularly to hold the gas pressure. Not using it all winter causes the seals to shrink and the gas to escape.
If you had lost all gas, the clutch would not engage so the probability is that you have lost enough gas over the winter to make the system inefficient.

If the air cond has never worked correctly since the re-gas, it is just possible that it was overfilled. If you did it yourself, or the garage just pumped a whole bunch in, the system will have gone beyond the most efficient point and again barely getting cold.
To work well, airconds must have just the right amount, not too much, not too little and be used every week.

Cheers,

Andy

4 degrees North of the equator....Aircond on 100% of the time!

[duncan]

Hi,
Before guessing what the problem could be, use the built in self check feature of the climate control unit. This can identify which of the 4 possible sensors, or 4 possible control motors that could have failed. From nsxprime.com either download or view Section 22 [Climate Control] of the factory manual and see pages 22-12 to 22-14.
If you don’t feel happy about working on the car yourself you can always pass a copy of the factory manual to a garage or workshop you trust.

[eclipse1501]

Hi,
Before guessing what the problem could be, use the built in self check feature of the climate control unit. This can identify which of the 4 possible sensors, or 4 possible control motors that could have failed. From nsxprime.com either download or view Section 22 [Climate Control] of the factory manual and see pages 22-12 to 22-14.
If you don’t feel happy about working on the car yourself you can always pass a copy of the factory manual to a garage or workshop you trust.

Thanks very much for the guidance to this resource, its really helpful in eliminating possible problems. Just printed off the self diagnostic tests and off to try them out, cheers.

[eclipse1501]

Hi,
Before guessing what the problem could be, use the built in self check feature of the climate control unit. This can identify which of the 4 possible sensors, or 4 possible control motors that could have failed. From nsxprime.com either download or view Section 22 [Climate Control] of the factory manual and see pages 22-12 to 22-14.
If you don’t feel happy about working on the car yourself you can always pass a copy of the factory manual to a garage or workshop you trust.

Brillaint advice Duncan and the self diagnostic on the AC offered a Fault Code D report, a coolant temperature sensor which the manual says is a heat dependent resistor located just behind center console. Thanks again for some really useful input and the link to the on-line resource you mentioned for anybody else needing it at prime is:

http://www.nsxprime.com/FAQ/Reference/1991_svcman/1991servman.pdf