April 27, 200717 yr comment_207354 Though that isn't the best way to connect them, it shouldn't cause the problem. I'm leaning toward the possibiliby that you may have inadvertantly disconnected something while changing the connectors since the car ran okay before. Link to comment https://www.classiczcars.com/forums/topic/24104-280z-dies-when-ac-is-on/?&page=2#findComment-207354 Share on other sites More sharing options...
April 27, 200717 yr Author comment_207361 Though that isn't the best way to connect them, it shouldn't cause the problem. I'm leaning toward the possibiliby that you may have inadvertantly disconnected something while changing the connectors since the car ran okay before.i am going to check and see if i disconnected anything, i will post pics of the area i worked on for more opinions.:nervous: Link to comment https://www.classiczcars.com/forums/topic/24104-280z-dies-when-ac-is-on/?&page=2#findComment-207361 Share on other sites More sharing options...
April 27, 200717 yr comment_207386 Vac diagram if you need it. Link to comment https://www.classiczcars.com/forums/topic/24104-280z-dies-when-ac-is-on/?&page=2#findComment-207386 Share on other sites More sharing options...
April 27, 200717 yr comment_207391 Here's the electrical info: Link to comment https://www.classiczcars.com/forums/topic/24104-280z-dies-when-ac-is-on/?&page=2#findComment-207391 Share on other sites More sharing options...
April 27, 200717 yr Author comment_207404 ok heres an update! so i looked at where i did the work on the connectors, nothing out of place everything connected. so I decided since i was under the bonnet to go ahead and set the idle back to stock, because at 400 rpms it wasn't even close to what the fsm recommends. so i set it to about 800 rpms and what do you know turned the ac on and reved it, and problem is gone. drove the old girl around with the ac on and she ran like a champ no stalling or dieing. thank you guys so much for all the help and the link to the fsm. Link to comment https://www.classiczcars.com/forums/topic/24104-280z-dies-when-ac-is-on/?&page=2#findComment-207404 Share on other sites More sharing options...
April 27, 200717 yr comment_207424 Glad you got it solved without having to mess with the vaccum lines, etc. Actually, the idle shoud be set to 800 rpm with the ac on but if it's working maybe you should leave it where you have it. I hate working on the vaccum/electrical parts of the old Z/810/Maxima AC systems and I'm a MVAC/HVAC tech. Link to comment https://www.classiczcars.com/forums/topic/24104-280z-dies-when-ac-is-on/?&page=2#findComment-207424 Share on other sites More sharing options...
April 27, 200717 yr comment_207443 Glad you solved the problem! Link to comment https://www.classiczcars.com/forums/topic/24104-280z-dies-when-ac-is-on/?&page=2#findComment-207443 Share on other sites More sharing options...
April 27, 200717 yr comment_207447 Now you know why they used to say that it was more fuel efficient to drive with the window down, as opposed to using the air conditioning. Those old piston compressors ( like on vintage Mustangs) must have needed 20 horsepower just to keep them going, compared to the newer rotary pumps. Even the four-bangers now come stock with a/c now, and they still get 30+ MPG. Link to comment https://www.classiczcars.com/forums/topic/24104-280z-dies-when-ac-is-on/?&page=2#findComment-207447 Share on other sites More sharing options...
April 27, 200717 yr comment_207449 Speaking of them taking away, hp, what would you guys estimate the stock factory a/c on these cars take away? The reason I ask is I've got mine all hooked up and plan on making an appointment soon to get it recharged and was a little curious on how much you thought it took away. Link to comment https://www.classiczcars.com/forums/topic/24104-280z-dies-when-ac-is-on/?&page=2#findComment-207449 Share on other sites More sharing options...
April 27, 200717 yr Author comment_207450 Now you know why they used to say that it was more fuel efficient to drive with the window down, as opposed to using the air conditioning. Those old piston compressors ( like on vintage Mustangs) must have needed 20 horsepower just to keep them going, compared to the newer rotary pumps. Even the four-bangers now come stock with a/c now, and they still get 30+ MPG. well i never really notice the drop in hp when i am using the ac, my other car 89 acura legend drops very noticeably. this compressor looks alot like the same kinda compressor thats in my legend. all the ac equipment is new on my z. has anybody ever installed a rotary compressor on there z? Link to comment https://www.classiczcars.com/forums/topic/24104-280z-dies-when-ac-is-on/?&page=2#findComment-207450 Share on other sites More sharing options...
April 28, 200717 yr comment_207481 I would say that the amount of horsepower needed to turn the a/c pump depends on the pressure inside when compressing. I forget the equation, but you can directly relate psi to horespower. Don't forget to add a little for friction, slop or the current date. Link to comment https://www.classiczcars.com/forums/topic/24104-280z-dies-when-ac-is-on/?&page=2#findComment-207481 Share on other sites More sharing options...
April 28, 200717 yr comment_207482 ...... has anybody ever installed a rotary compressor on there z?Your's is a rotary compressor. The piston type were used on the early 240 aftermarket installs. I have non factory air with a Sanden compressor and I don't notice an appreciable loss of power when it's on. Nor do I notice it in my 810 which has essentially the same system as your 78. I'd rather be comfortable in the heat than worry about a few lost hp or a couple of mpg. I'm not racing. Link to comment https://www.classiczcars.com/forums/topic/24104-280z-dies-when-ac-is-on/?&page=2#findComment-207482 Share on other sites More sharing options...
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