Wade Nelson

Yes, you can get a system that's low on Freon working again, somewhat, by adding Freon. Fixing the places its leaking, is of course, vital. But what's gone missing from this discussion is the importance of evacuating the system, and replacing the receiver/dryer. That is, using a vacuum pump to suck every last bit of air out of it. And boil any water out of it. (Water boils at room temperature in a vacuum) In the olden days you used to pull a vacuum and let the AC system sit overnight. These days the pumps are better. Simply putting an empty R12 can in an ice bath ain't gonna do much to the remaining air/water vapor in the system, even if it does condense out a few droplets of R12. As far as being "ecologically correct" virtually every car made from 1964 to 1993 eventually lost its freon into the atmosphere, that's tens of millions, one more pound of R12 isn't likely to destroy the ozone layer. The only "real" reason to recycle it is to avoid buying more, but since yours is 99% likely to be contaminated..... The EFFICIENCY of your air conditioner, whether it's R12 or R134 based, is determined SOLELY by the amount of water (vapor) and air CONTAMINATING the system when you are all done. Even a tiny amount can reduce your efficiency by 50% or more. You put it on HI and only get cooled air instead of 34 degrees freezing you out. This was the "big truth" I learned after years of replacing parts, sealing leaks, adding more refrigerant, etc. It's not how MUCH R12 you've got in there but how pure it is. The receiver/dryer is chock full of the same stuff in those little silica bags that come with new products. Its job is to absorb any water vapor that gets into the system -- by way of humid air that sneaks in. After 20 years, your receiver/dryer is most likely saturated. It can no longer do the job it's designed to do. Replace it, especially if you're springing for a new compressor. (Front seals on compressors --- #1 leak spot for refrigerant) Once you've FOUND all the leaks in your system, and sealed them --- new hoses, new o-rings, leaking schraeder valves (Nissan replaced a lot of these when I worked there...) and front seals on AC compressors, and condensors with pinholes in them from rocks hitting 'em. Again, once you've FOUND all these leaks and sealed them, THEN it's time, along with a new receiver, to pull a mighty vacuum on the system, to suck 99.9999% of the air out. This will ALSO "boil" any remaining water / water vapor in the system allowing your new receiver to do it's job effectively. So often it's a two step process, you shoot in a SMALL amount of $$$ refrigerant and dye, identify and seal the leaks, THEN replace the dryer and pull the big vacuum, and go for the final charge. The equipment is called a "micron" gauge, and a "micron" pump, which pulls your system down to, say, only a million molecules of air and water. They're not cheap, which is why only AC professionals own them. I happened to get lucky and find one in a pawn shop. Along with the halogen detector you need to "sniff" really small leaks, like out the schraeder valves. We're talking a few thousand molecules a minute. And the other thing is, if you add Freeze-12 or R134 with "stop leak" in it, no AC professional will ever work on your system for you. That stuff will RUIN their expensive gauge and pump. so they test your system for it before they hook up to yours. Now really, with 150 psi, do you really think adding some "goo" is gonna stop your refrigerant leak? Sure, maybe 1 out of 10 leaks will be healed by it. 90% wont. How often does "slime" actually work to fix a flat tire on a bike? I was wrong in an earlier post, R12 on Ebay seems to have declined in price, considerably. So a R134 conversion is no longer economically mandatory. But remember, you'll probably waste ONE can of R12 just FINDING your leaks. I'm not telling you you can't, or won't have some success working on your own AC system, as Fastwoman proves right here. But finding and working with a true AC professional, and doing it right, doing it once, which will NOT be cheap, can in the long run be cheaper (and far less frustrating) than doing it piecemeal, and only getting mediocre results. The best AC man in the USA is a guy by name of Glenn Farrell down in Louisiana. He's the one who "educated" me. Good luck!

BTW, stay away from 4-Runners yeah, they're SUV's for midgets. I'm 5'8 and can barely squeeze in beneath the steering wheel. And I'm not fat, either.

My car has a noticeable problem vapor locking on warmer days. Today's "low-emissions" "oxygenated" fuels with added alcohol are MUCH more prone to this problem, when I fill up at a particular fuel wholesaler that has "no-alcohol" gas the problem goes away completely. Has anyone solved this problem FOR GOOD on your 280Z or ZX? I've replaced the Wells, SW541 switch that controls the auxiliary fan that's supposed to cool the injectors after shutdown. Problem is my coolant never seems to get hot enough to kick it on. Yes, i've tried grounding the wire, and the fan runs just fine, times out, etc. Yes, thermostat working fine. So I went to the Wells site, hoping to find a switch (mine has 210F printed on it) with a lower rating, maybe 190F. Unfortunately they don't have anything with the same thread pitch 1/4 x 19 as the SW541 to replace it with. Anybody know anything about Beck/Arnley or other suppliers? How often does YOUR aux fan run? Every shutdown? Occasionally? or Seldom, like mine? Maybe some hard water crud deposits in the flange itself is preventing hot water from directly hitting my sensor... I'm thinking of mounting a toggle switch on the dash to ground the circuit on hot days and just flip it back off in the wintertime when the aux fan is unneeded. Fool the system into running the AUX fan every time I shut down. Esp on sunny days. The idea of a "prime" toggle switch to run the fuel pump and circulate cooler fuel for 20 seconds before cranking makes sense, that's got to be cheaper than replacing worn out starters. I have to believe a lower kick-in temp on the aux fan would make a big difference.

I didn't bother to read the entire thread, but a failed Throttle Position Sensor will cause you to lose power under load, runs fine most of the time otherwise. Not too hard to do a quick check on with a VOM.

Did you get this fixed? What was the cause? I was going to suggest looking at the Auxiliary Air Valve, but sawyour post was 5 months old.

Yes. That's it viewed from the bottom, seeing the barbs the hoses go on. Mine had more barbs, is that perhaps one for the automatic climate control?

Pics or it didn't happen. (2)

http://www.caranddriver.com/reviews/1979-datsun-280-zx-first-drive-review Interesting comments, including "mashed potato" suspension. I believe my expectations about the 280ZX's handling capabilities were too high, even after replacing all sorts of front end componentry. My other sports car is an MR-2, which handles nothing short of superb. I'm not willing to suffer a noticeably rougher ride to tighten the Z up much more. I may still go with a thicker front sway bar, and haven't done the rack & pinion mounts yet.

Only remove the BCCD or other emissions control devices if you have SOLID evidence they have failed and/or negatively impacting the operation of your vehicle. Theoretically all the BCCD is going to do is cut fuel while your engine returns to idle as you coast or engine brake down, also preventing backfires. That's a good thing, a single backfire can destroy your AFM. And cutting fuel when the engine isn't supplying power saves fuel. There's simply no real benefit to removing it unless it has failed in some way. Instead learn how it works, test it, read the Datsun fuel injection manual on adjusting it IF you think it's misbehaving, (manual available online as a .pdf) and in general LEAVE IT ALONE unless you have a valid reason to remove it.

Some of the best techs in the country belong to www.iatn.net. The public can use the front page of the website to find IATN members in their area. What I would do is get one or two IATN member names, CALL them and ask "Who in this area can diagnose an older fuel injection system on a Z, similar to a L-Jetronic." You may end up with an old Mercedes or BMW tech. They'll have it fixed in a matter of hours provided your cat isn't destroyed, and you aren't missing all sorts of parts.

Hey Zed --- any reason not to just put a resistor inline with the AAR and slow down the rate that it heats up? My AAR is 60 ohms, so if you added another 60 ohms, it would take (at least) twice as long to heat up and pull off. You'd need a 1.2 watt (capable) resistor. Maybe use an old ballast resistor if radio shack doesn't have what you need. Remember, you could take TWO 1-watt, 100 ohm resistors in parallel for 50 ohms @ 2 watts, 3 half-watt, 180 ohm resistors in parallel for 60 ohms @ 1.5 watts, etc...

Here's an AAR cut apart, showing the guts, on another Z website. FWIW, this site has dozens of great tech tip articles. http://atlanticz.ca/zclub/techtips/aar/index.html

thanks for the link. That's a fabulous diagram and a very good overview. Re: AFM vs. MAF --- air flowing through either one will get measured and fuel metered for it. My point was that a wide open AAR isn't going to enlean the charge. I realized the post was 2 years old, but figure correcting the archive of info here, a real treasure trove, is just as important as correcting current posts.

Auxiliary Air Regulator --- Testing and Adjustment by Wade Nelson My 280ZX doesn't start as consistently and quickly as a fuel injected vehicle should, which is immediately on the first crank. Sometimes it takes several cranks, sometimes it'll barely catch and I have to pump the throttle to get it up to a normal idle speed, all of which indicate something isn't right. But from then on it runs great, so I've never worried too much about it. Bigger fish to fry... I also noticed I don't seem to get much if any idle-up on cold starts, higher RPMs which should gradually decrease. Themotyme / Cold start injector APPEAR to be working, at least intermittently, so this pointed me towards the AAR. (Yes, I could do MORE to confirm they're working 100%...) First, I got in the archives here, and then in the FSM. Posts in the archives indicate the AAR unit rarely fails. If it had, Rock Auto has 'em.... https://www.rockauto.com/catalog/x,carcode,1209316,parttype,6072,a,Search%2Bfor%2B1983%2Bnissan The AAR consists of a rotary shutter which gets rotated as a bimetalic strip heats up and bows, powered by the battery. (of course ambient temperature will also affect the strip...) The shutter, normally open, rotates shut as the strip heats up. There is a calibration screw on the unit, typically its painted over to prevent tampering. What I did was remove the unit from the car. On a 70 degree day, the shutter was completely closed. I used a small pick (icepick) to carefully try moving the shutter. It seems like it was initially slightly stuck, I observed a fair amount of carbon buildup in there. I was careful not to damage it, but after being opened once it then operated smoothly. Maybe I was getting no auxiliary air at all. Next was cleaning. I'd have preferred to use some stronger CARBURETOR cleaner, but all I had was brake cleaner. Sprayed some in from both ends, sloshed it around a bit, poured it out. Couldn't see that I'd done much carbon removal, but the shutter moved smoothly. Next I tested the heater with my ohmmeter. 60 ohms, right on the money. Manual sez 25-90, but the unit itself is stamped 60 ohms. Next I threw it in the freezer for 30 minutes to see if the shutter would open completely. It did not. Only closed about half-way So I decided to try and "calibrate" the thing. This may not be the RIGHT way to do it, but time will tell if it works well enough. I figure at 32 degrees or below I need as much idle-up as it can give. After freezing, I loosened the adjustment nut, held the shutter completely open with a pick, and re-tightened the nut. (The alternative calibration procedure might be to warm the thing completely up, electrically, and re-tighten with the shutter completely closed) It would still stay about half-way open after this procedure. Still cold, I applied 12V to the terminals, and watched, as over the next 2 minutes the shutter SLOWLY closed from the half-way open position. Ok, so at least it should completely CLOSE, which is the most important thing, since I only drive this thing in the summer anyhow. (Since it's just a heating coil polarity shouldn't matter when you juice it...) Results? Hard to tell. After letting it sit for 15 minutes while I wrote this, I went out and started it up. It started right up, idled at about 750. After a full 2 minutes it seemed to decrease down to about 650. Of course it's 70 degrees out, so it's hard to expect MUCH in terms of idle-up or down. I suspect on a colder morning the effect, if I helped matters any, will be more apparent. If not, I may try the alternate calibration procedure of locking the shutter down when it's completely warmed up. HTH

>The AAR is still dumping all kinds of extra air into your manifold, creating a super lean mixture, which could, I suppose, in theory, kill the car and then make it hard to start again 'til it's cooled down. Wrong, wrong, wrong. The AAR picks up air downstream from the Mass Airflow sensor. That means that ALL air passing through it has been metered. The ECM will inject fuel to match the amount of air metered. So the AAR is not just "dumping all kinds of extra air" and making the engine run lean. When the system is working AS designed, not only is the MAF adding fuel to accompany any air passing through it, and later the AAR, but the Thermotyme system is DOUBLY enriching the charge since both thermotyme and AAR should both only be flowing during the first 30-60 seconds after startup.

I put it on the opposite side of the ashtray. Nothing there on my car but a blanking plug. NAPA's also got some with a bracket you could hang below the dash.

Since the dash is out for a stereo install, I decided to add a second lighter jack. That way I won't have to constantly unplug the radar detector to plug other stuff in. (And my Valentine plug didn't like the 280 lighter jack for some reason. It's a "1601" jack at NAPA, cost, $7, plus a little effort to wire. Ideally you want one jack that's always powered, and one that switches with ignition. That way your radar detector doesn't stay on in the parking lot, but you can play your Ipod or whatever, whenever, OR plug in a solar battery charger if your car sits for a long time.

The factory original is a three wire system, blue, blue and red, and blue and yellow? The switch routes power to the blue and red to raise the mast, blue/yellow to lower it. Aftermarket antennas, and modern stereos don't work that way. Today you supply 12V to the antenna, which tells it "hey, he just turned on the radio" and it raises the mast. When the 12V goes away, it lowers the antenna. The 12V isn't the SUPPLY power to the antenna, just a SIGNAL. So you can leave the ORIGINAL antenna, and ORIGINAL switch, and raise and lower your antenna yourself. Or you can go with an aftermarket antenna, and use the "blue" wire out of most stereo heads to have it raise and lower automatically. This blue wire is ALSO used today as the "remote" input to turn on amplifiers, etc. HTH

The "Wheel of Death!" as we refer to it in the shop! Eye protection is mandatory!

Here's a simple way to reduce your chance of warped rotors / pedal pulsation when you do a brake job. The root CAUSE of warped rotors (disk thickness variation) is runout in the hub itself. Basically, what that means is the hub, hence the rotor, is TILTED, ever so slightly. (If you want to argue the cause of warped rotors, google "warped dtv" and then get back with me) You can put a dial indicator on the rotor (1/4" from outside edge) , and index the rotor, basically, try it in the 4 different positions on the hub and see which produces the least runout. If you're not a professional mechanic, you probably don't have the slick setup for doing this. The easiest thing to do is this: When installing new rotors, take a zip disk, (3m abrasive pad on a die grinder) and be sure you remove absolutely all rust, grit, and grime from where the rotor mates to the hub, so they mate perfectly! Even a speck of rust can tilt the rotor ever so slightly, causing runout. Do that and chances are you'll avoid warpage even if you don't bother indexing. The reason on-car brake lathes got so popular is no matter how the rotor is tilted, they're gonna cut it in-plane. But with new rotors selling for $25 or less, who would bother measuring and cutting an old one anymore?

If you haven't discovered RockAuto dot com, check 'em out. I'm buying ALL SORTS of 280ZX parts there, usually for less than they're going for on Ebay. Stuff you would assume is out of stock, forever. Turn signal switch, idle air control valve, ignition switch, blah blah blah. Very competitive prices. Paid $3 apiece for some new front brake hoses. Most stuff ships the day you order and arrives within 3-5. I did a TOTAL front brake replacement -- hoses, calipers, pads, rotors --- for less than $150 in parts! I found the castle nuts holding my front hubs on were only finger tight. The last "mechanic?" forgot to torque it down apparently. Jeez, no wonder the thing felt so loose!

If you feel the vibration in the steering wheel, it's related to the front tires. If you feel it in the seat, it's related to the rears or driveshaft / propshafts. Generally a tire problem on a 15" tire is going to give you a shake at 55mph or so. I SUSPECT you have a bad u-joint or prop-shaft that is giving you your 65mph vibration. Put it on jackstands, remove the wheels, and run the engine up to 3000 rpm in 5th, or have a friend do so while you WATCH the propshafts for vibration.

Did you get your problem figured out? How about posting a follow-up so others who might have a similar problem in the future can benefit from your experience.

Okay, I got this thing fixed. None of my vacuum lines were cracked or off their barbs, all the HVAC door motors were working, hot/cold cable adjusted properly and so on. That only left one thing. The control head. The way it works is it has two disks that rotate relative to each other. The bottom one has 8 hose nipples on it. The top one is toothed, like a gear. Apparently the upper disk has a variety of passageways in it, and rotating the selector knob lines them up with various nipples on the bottom disk. Don't ask me how it got that way (It seems virtually impossible) but the disks were mis-aligned. I put the selector on VENT, where air was blowing out the vents I wanted for AC, pryed the toothed lever up so it wouldn't rotate the top disk, and rotated the selector lever to the coldest (furthest left) AC position and set it back down. I then tried it in all the other positions, and air came out the right vents, including defrost. I simply cannot imagine how this disk got mis-rotated, but it did. Someone installed a new control head and didn't line it up? It wasn't from hitting a pothole, it took considerable effort to pry the lever up above the top disk. Now, here are TWO things I realized that will HELP you diagnose YOUR system when the air comes out the wrong vents. When the selector is on VENT, ALL of the vacuum ports should be connected to vacuum. Every vacuum motor should be actuating. When the selector is on RECIRC (far right, past defrost) NONE of the vacuum ports should have vacuum. I still have ONE issue, which is the AC quits coming out the right vents when I floor it and lose vacuum. My guess is I'm missing a one-way valve up at the vacuum reservoir, or else it's stuck open. Alternately, a small but continuous vacuum leak somewhere could cause the reservoir to be depleted. This one should be easy to fix, can use a smoke machine if necessary. HTH

p.s. Never, ever use R-134 with "leak stop" in it, which a lot of backyarders do trying to do their own R134 conversion. After injecting leak stop into your system no AC shop will ever touch it. It will screw up their very expensive equipment. And "leak stop" doesn't work in a 300 psi system anyway.