View Full Version : N13, reverse gear A/C on. Why'd they remove this feature?

18-02-2017, 11:40 AM
When must Mum bought her new N13 back in 1989, when you put it in reverse the A/C cycled on. This was apprentice to keep the gas circulating and keep seals from drying out. That sounded like a good idea to me. However it seems following models, nor any other car I've ever had, did this. We always wondering why.
These are the only reasons I cam think of why it isn't done now.
1. You weren't in reverse long enough to make any difference to the A/C system.
2. Confused too many people as to why the revs increased.
3. Maintained the system so well that Nissan lost out on spare parts sales.
4. Gas is always in contact with all seals so it was a waste of time/energy anyway.

So, any ideas? Thanks.

18-02-2017, 01:01 PM
Gas isn't the issue, its the lubricating oil that is in the system that most people don't realise is there is its designed to circulate. If you told someone that there is OIL in the gas pipes for the a/c they would probably look at you funny.

It will also help to keep the clutch engagement surface clean and stop the clutch from ceasing up.

Likely a combination that it confused people and was the source of may trips to the dealership. It probably also contributed to extra wear on the mechanism but that's not likely to have produced increased number of failures i wouldn't think, given the fact that engaging at 3000rpm would be far more stressful for the mechanism than engaging at idle.

Just one of those things that turned out wasn't necessary on later models i suppose.

18-02-2017, 01:22 PM
Thanks Cozzm0. I'm the 1st to admit I don't really know how A/C works, and I'm looking funny myself at the "Oil in pipes" statement. Might google/youtube it and learn some more.
Also, this part, "given the fact that engaging at 3000rpm would be far more stressful for the mechanism than engaging at idle". I'd never even thought about that. Will now turn mine on at idle speed, as that makes complete sense.

18-02-2017, 02:51 PM
When you're driving, the A/C clutch cycles on and off as the temp goes down, so really you can't do anything to stop that. Its how they're designed anyways, but just making the point that driving along, at 100km/h on the freeway at 3krpm the a/c clutch will click on and off probably every 30 seconds. Also A/C clutch is automatically disengaged at full throttle, but will immediately engage when you let off, which means it will engage at 7000rpm ... They're designed for it, but the higher the rpm difference, the more stressful for any clutch.

18-02-2017, 05:02 PM
Excellently described from you, as usual. My own system doesn't seem as cold as I'd expect. But I've had it over a year now and no idea if precious owner ever had it serviced/regassed, so that may be on the cards. Seen it advertised for about $100.
About to drive car to shops and am going to stick my digital temp pen in the vent and see what the temp is down to anyway.

18-02-2017, 07:36 PM
Well, I checked the temp in my car at the vent. Lowest was 43f and cycled back on again at 48f. I think those temps are okay, but would prefer colder.
I always remember a tow truck that I needed a lift in when one of my cars broke down, with the vent pointing at me I was freezing. It was stupidly cold, but I so much wanted car cooling like that.

18-02-2017, 07:57 PM
Those temps are absolutely fine (after i googled and converted them to real temperatures). Much cooler and it will freeze over the evaporator totally, the A/C must stay above zero. The actual temp at the evaporator will be colder as ice does form on it and then melts when it cycles off (that's why cars leave a pool of water when the a/c is running).

One thing i will mentioned about trucks and vans, the volume of air the a/c system is cooling is 1/2 or less of a car. Can always get the charge checked to ensure its correct, but those numbers really do seem OK to me.

18-02-2017, 11:15 PM
Thanks again. Sorry about the yank temperatures. My digital pen was set for farenheit as that's what I use when doing bbq and I didn't have a paper clip in the car to change it to Celsius.