1977 280z AC -- issue # xx of yy

[240zadmire]

Hi all,

My AC system is stock or at least what I been told.  Always use R12 and haven't converted to R134 yet.  The fitments on the compressor still R12.  Not like the R134a where one is bigger than the other and sometime caps color coded.

I read online, forums, including this one and seem like people stating that R134a can be run on R12 system provided flush all refrigerant, new fitments, run not as cool as R12, high pressure....

Knowing R12 is no longer available or at least at authorized AC shop.  The dilemma  I have is that I'd like to keep the car as stock as possible.  Which lead to parts hard to find and sometime impossible.

Seem like there is a company have the equivalent to R12 calls Frostycool R12a.  

 

questions below:

- has anyone use this product before on the stock R12 system?

- I need an A/C drier though the fitment of the tube/pipe need to bend a bit to connect to this.  Is this one work well with stock AC? TCW  I also need a high switch.  I suppose unscrew the front bolt on the driver for the high switch.

 

 

Much appreciate

 

 

[Dave WM]

I would try harder to find someone that will work on R12 OR just do a conversion to 134a. I don't know much about those R-12a products, but pretty sure most AC shops do not use them either.

If you convert to 134a, you would want to replace everything in the engine bay and flush the EVAP well. I would think a universal fit PF condenser would be better than a flushed OE one. The PF condensers are supposedly more efficient that the tube/fin type that is stock, and from what I have read R134a will need that to operate correctly.

The main problem area IMHO is the condenser it sits out there in harms way taking rock strikes etc...

Also you need to consider what about the compressor? are you replacing it? there is oil in there as well that needs to be considered in a swap. I have the old SWP123 style, its huge and heavy but very durable. Most folks opt for the modern SD style either real Sanden or clones. Pretty sure if you get one new it will come preloaded with pag (non compatible oil with R12, for use with R134a).

[Dave WM]

I forgot to ask what is the current working status of the stock system?

[240zadmire]

Hi @Dave WM

I don't know the condition.   The car sat since 2004.  I didn't ask the previous owner.  My bad.  though the belt was loosen from the compressor.  Figure it wasn't working for awhile, that why the belt was loosen up.

I strip the car down nut by nut, bolt by bolt to  rebuild the engine.  When I opened the hose/condenser/compressor ... oil/refrigerant still there.  I thought It was dried up but I guess still some left.

I have the SWP123 as well.  Seem to be in decent shape.  It is mounted to the car now.  Wonder how do I check to see if it is still working.

about replacing the whole thing in the engine bay.  that will cost a pretty pennies.

 

regards

 

[240zadmire]

anyone use this kit?

 

https://nostalgicac.com/datsun-240z-260z-280z-compressor-upgrade-kit.html

 

[Dave WM]

too late now, but generally speaking best thing to do is in an unknown would be to see if the compressor is locked up, if not connect up some gauges and see if there is any pressure, if not then pressurize the system with nitrogen and get out the spray bottle with water and soap and see if you can find leaks. If no leaks and it holds the pressure, then try pulling a vacuum and see if it holds. if it does then recharge with R12 (supply it directly to the AC tech for find a shop that will do it, they are around).

As now with it apart I would tend to go with all new parts and plan for a 134a. the thing about that kit is you still need the condenser for the R134a, I would not trust a 43 year old condenser.

It will take some fabrication. there are direct fit condensers but they are the tube/fin style and not PF, I am not sure that would be best with R134a.

replacing everything up front will get you up to about 800-1000 depending on how you go. AC is not cheap.  

[Dave WM]

As far as checking the SWP123, you can hand spin it, see if pushes out air. other than that hard to say. If it has been open to the air its likely to have some corrosion inside, not good, unless it had some pressure to keep out the humidity or if it was in a very dry climate.

[Dave WM]

the cheap approach would be t hook it all back up tighten all the fittings and do the checkout procedure I outlined above with pressurized air and then the vacuum. My system had a slow leak, replacing the condenser with a NOS one fixed that, a new drier and recharge with R12 , its been 4 yrs at least, still works great.

[Dave WM]

Depending on the environment the interior of the car saw (heavy smoker as an example) the evap may be clogged up with tar/dust reducing the ability for the heat transfer to take place. The other issue is if the expansion valve is ok or not. if its bad its NLA. the upside is you can buy brand new evap and it uses a common expansion valve, the bad news is its expensive like over 300$

The only way to know for sure is visual exam of the fins on the back of the evap. Not an easy thing to do. If its plugged up, the sys will not work  right and you will have odd pressure readings.

If the expansion valve is ok, you can clean the evap but again its a pita. would be hard to do with the dash in place, I would pull the dash rather than trying to fish all that stuff out, if possible at all.

[Dave WM]

A lot of folks just say F it and decide to go with an after market system. while true you don't have to worry that its going to work, there is a heck of a lot of fabrication so its not exactly easy, and its still expensive.

I would go with plan A reassemble/test/get lucky change drier,pull a vacuum  and recharge with R12

Edited August 14, 2020 by Dave WM

[240zadmire]

All I read is $$$$ and more $$$$$

appreciate everything you said.  I will try least $ first.  Grease elbow is no problem.  Worse case, leave all windows down and the windshield hasn’t install yet.  Might keep it uninstalled.  It’s 95 degree today and I feel great having resolve the fuel light issue thanks to you and other folks 

[Dave WM]

yep try the easy 1st always a good idea. I can tell you that with the stock system working its pretty good. here in sunny FL we get days will in to the upper 90's with high humidity. With the rear louvers it will keep up with the heat to provide a comfortable ride. You cant slaughter meat inside but its good enough that I can turn it off max after a while. The key is to keep the car out of sunny parking. with that the heat gets so high that it takes a long time to overcome. It so hot inside that you cant touch the dash. If I park in the shade or come out of the garage its never an issue.

Black vinyl is not the best for keeping cool and the insulation on the headliner is pretty minimal. add to that the dash radiating heat and you are behind the eight ball.

That being said I did a cross country (well 1/2 country) trip and was fine this was in early sept when it was still quite hot.

Edited August 14, 2020 by Dave WM