75 280Z with stock A/C, what's it gonna need?

[Daeron]

I am very close to clueless when I think about bringing the AC back to life in my car.

 

The car is in "pre-project" stage, meaning i am not doing squat with it right now.. but any time I start thinking about the AC I find that I don't know where to begin. The entire factory system is still there, and i think it even functions (can't recall) and I have a complete spare control console anyhow.. but what I don't know is what I am looking at to try to bring it back to life. Never, in my ownership of the car, has it worked. (since Y2K)

 

What am I looking at? Rebuild the compressor (I am sure I could do it) or replace with a remanufactured unit? Is the stock componentry even worth messing with, since I don't want to bother with trying to find R-12? Possibly try to find a not-TOO-dissimilar unit off a later model vehicle (using R-134A) from a junkyard? Maybe recon the junkyard condenser, too? What lines might I keep, and what might need to be replaced with newer parts?

 

I know a LITTLE bit about Auto ACs, and I understand what goes into an air conditioner well.. but I don't have ANY experience whatsoever, and am really rather ignorant on the entire topic. Any help, advice, links or literature is appreciated!

[Clifton]

I can't speak for the 280 a/c as I have a 240 but if it is anything similar I would get R12. R134 would not cut it on mine out here, R12 doesn't over 105* for very long. It is still easy to find, around $20-30 a can. 3 cans is more than enough. 2 did my 240. You can get just compressor seal, they are easy to replace if yours was leaking. I did mine. I would changed the dryer and any O rings in the system, if 280's use them.

[Powerglide]

I live in Lake Worth, Florida.... HOT, HOT, HOT here. R12 is a MUST. You need 3 1/2 cans. Buy them off E-Bay. Will cost you $40 a can. Confirm with the seller that they are full. Don't use Freeze 12 or any other substitutes. OK...now the painfull part ($$$). You need a NEW compressor, a NEW drier, a NEW evaporator with a NEW expansion valve, and a NEW condensor. Also suggest you pull the interior fan and clean it as these old stock fans are feeble and get worse when they are dirty. Also check ALL your vent hoses, making sure they are connected properly under the dash. I strongly suggest you have the system flushed properly by a COMPETENT a/c tech, He'll probably suggest you replace the a/c hoses too. I also suggest you check the BLEND DOOR for proper operation. If it doesn't work right, you'll be mixing warm air with cold and will severly reduce your a/cs cooling. Check to see that you enginge's clutch fan is tight, too. If it all comes together properly, you should get 44 degrees---or LOWER---in our S. Florida heat at cruising speeds. You car's cooling system also needs to be in perfect operating condition to avoiding overheating in traffic.

[Daeron]

I live in Lake Worth, Florida.... HOT, HOT, HOT here. R12 is a MUST. You need 3 1/2 cans. Buy them off E-Bay. Will cost you $40 a can. Confirm with the seller that they are full. Don't use Freeze 12 or any other substitutes. OK...now the painfull part ($$$). You need a NEW compressor, a NEW drier, a NEW evaporator with a NEW expansion valve, and a NEW condensor. Also suggest you pull the interior fan and clean it as these old stock fans are feeble and get worse when they are dirty. Also check ALL your vent hoses, making sure they are connected properly under the dash. I strongly suggest you have the system flushed properly by a COMPETENT a/c tech, He'll probably suggest you replace the a/c hoses too. I also suggest you check the BLEND DOOR for proper operation. If it doesn't work right, you'll be mixing warm air with cold and will severly reduce your a/cs cooling. Check to see that you enginge's clutch fan is tight, too. If it all comes together properly, you should get 44 degrees---or LOWER---in our S. Florida heat at cruising speeds. You car's cooling system also needs to be in perfect operating condition to avoiding overheating in traffic.

 

 

What's to stop me from just getting the condensor, drier, etc from a more modern vehicle, that uses 134A, and retrofitting them onto the car? If I am spending big $$ anyhow, why spend it on stuff thats going to take the (admittedly superior) yet obsolete refrigerant? Seems like everyone in their new cars are happy enough.. am I just THAT ignorant of how much colder R12 is??

[mario_82_ZXT]

R12 is way colder!

 

If you just want to go with new parts, look up Vintage Air. A few guys on here have installed it and it's pretty neat and uses pretty much all new parts.

 

Mario

[Powerglide]

The system was designed for R12. It will NOT be as efficient with R134a, I speak from experience... Trust your gut though. 134a runs higher head pressures than R12. This can cause leakage. R12 runs with lower preasures and has a larger molecular structure. It has less of a tendency to leak. Go with your gut.

[Daeron]

I'm trying to go CHEAP, and as painless as possible. I am not an air conditioning addict by any means; I lived through five years in florida without it in the car; I WOULD like to fix it eventually, and I am just trying to get a realistic idea what I am looking at. Rebuilding the compressor thats on there, and replacing some seals, then spending a bunch of money on R12 to recharge it, MAY we be the cheapest way for me to go.. but I am not married to it.

 

Essentially I was looking to get some discussion going regarding these different ideas..

 

What I have come away with from this so far, has been that IF I wanted to retrofit an R-134A system, with modern components, into the vehicle, I would have to find the evaporator coil that goes inside the car, and replace the one in the Datsun with one of the same dimensions... That would make the project much more difficult, so I am guessing thats out.

 

What is so different about the condensors and evaporators for R12 based systems and R-134a? All I have been able to gather is that the condensors for 134a are larger area, because they need it.. but thats hardly any real info.

 

thanks for the responses!

[Zmanco]

I'm no A/C expert, and here in CO we don't have the same levels of humidity as you do in Florida, so with that disclaimer, here's what I did:

 

I started with my 73's dealer installed A/C system. It's pretty marginal on a good day. I replaced the original compressor with one from an 80+ ZX along with the better bracket and had the system refilled with R12. It worked pretty well, especially at freeway speeds.

 

But the R12 leaked out several times (always when I was working on another project and somehow must have "bothered" some of the old hoses) and I got tired of paying my local A/C guy to refill it.

 

This last summer I switched to Freeze12 which is basically a mix of R12 and R134. I found it on ebay and it was way cheaper than R12. The kit came with lubricant and stop leak which I added, and then refilled the system. I did that last June and so far all continues to work well. The cooling is not as good as with R12, but it's good enough for me, and also much cheaper.

 

I am not saying this is the best approach for a long term reliable a/c system, it's just what I did to keep it running since it's not that big of deal for me to have it.

[dapiper]

I bought an '78 system from a bone yard in TN last fall and had it converted to R134a. My Z had evap and controls from PO who removed system for performance. It cooled to 40F but leaked and the belt kept squeaking. I kept tightening until finally bought shorter belt. I have a BHJ harm bal with 6" X 5/8" pulley.

 

I must have refilled it 3 times in a year and just last month during a real hot spell, the compressor siezed. Datsun has different compressor and pulley every 6 mo of model year. Mine is boat anchor Hitachi with 8" pulley.

 

Now I will have to purge entire system and repl dryer and maybe other stuff. I have $700 installation and $130 in evap and recharges, another $40 in freon and just keep depleting the ozone layer as well as my wallet. Thank God its getting cooler now.

 

If I can get a cheap R12 compressor, like off old 280 I will try R12. But if it continues to leak, prolly should leave as R134a, since cheaper. Alternative is new, more efficient 134a Sanden compr ($200).

 

Cannot seem to get A/C mechanic to search for leak. Another guy wants to replace everything for $$$. If leak is in evap, will give up.

[niner11]

You can get your A/C up and running but I would start with a vac pump off of ebay. I did a lot of A/C work on my 911 and saved a fortune with my own equipment. ackits.com used to have some decent starter kits for DIY as well as rebuilt compressors.

 

I would start with a new receiver drier at a bare minimum but it would probably make sense to buy a rebuilt compressor as well. As for the expansion valve...they are not cheap and the oem condensors are NLA I believe. If you put a vac on the system you will be able to tell if it has any leaks ....who knows you might get lucky. Search around, if you go the r-134 route you will need to make sure the oil in your system is compatible and the amount used to service with be probably closer to 24oz or so.

 

Just some things to think about. Chuck

[Daeron]

:iospalo:Let's go digging.... bring it out, and take it back in... except I want it about FORTY degrees, COOLER. (Tool reference, great band)

 

So I was turning these questions over again in my mind, and I want to revisit this thread.

 

Despite hearing others say that converting their Z's AC to R-134a seems sufficient for them... I just don't know. 90% of the reason I want an AC is to be able to get in the car after, say, being out in the sun at the beach or fishing, and just turn it on full blast and get a smack of air at 32 degrees fahrenheit in the face. (Well, not literally that cold, but you get the picture..) So whatever, I will make up my mind on the refrigerant being used....

 

Anyhow, in reviewing the thread, I realized that I had missed my original thrust in the post by getting sidetracked into the possibilities of retrofitting newer components into the vehicle. My big question originally is.. What are the odds that I can go to the car, pull a vacuum, and have it hold? Am I probably looking at replacing many seals and O rings simply because the system has been, sealed to the best of my knowledge, but simply at atmospheric pressure for so long? (I've had her for 8 years now and it was dormant LONG before I got it.)

 

I understand that the receiver/dryer almost certainly has to be changed because it is a wear item.. but seriously, how would I proceed in reviving the system? Should I just get my brother to pull a vacuum on the system, and if it holds for a few days, buy a new receiver/dryer, and get some R-12? Or should I replace a few easy-to-reach seals first, should I check the oil?

 

I've been reading the A/C section of the 76 FSM I have handy... Also comparing to the 74 on my PC b/c the car is a 75 and the 75 FSM I have in PDF is missing the AC chapter. So I understand most of the procedures and what is involved.. I am simply not yet confident that I understand everything that I may run into. When I reached the section on compressor overhaul I started skimming, and only noticed a few seals involved..

 

 

It just seems too good to be true to think that I might be able to get by with simply replacing the dryer, buying some Freon, and charging it up. Is this THAT outrageous a possibility, and if so, what is most likely to be problematic?

 

TTBOMK, the answers are thus: (given that the receiver/dryer needs to be changed)

1. Compressor shaft seal

2. A few random O-rings like line seals and silencer O rings that are easy enough to get at

3. Evaporator Expansion valve

 

Beyond that, as long as my lines themselves, and the two coils (condenser and evap) are intact... it should just go, right?