R12 to R134a conversion advice

Technical Area Electrics & ICE
1
  1. My model of MX-5 is: 1990 Eunos 1.6
  2. I’m based near: Harlow, Essex
  3. I’m looking for technical help or recommendations on: R12 to R134a conversion

Ok so at some point I want to convert the ac in my Eunos from r12 to r134a. More to clear the screen quicker in the winter than use in the summer (i have the top down). For a start I have no idea how long the AC hads’t blown cold for. Had the car about 2 years now, literally only tried the ac the other day to see if there is anything left in the system. No change in temp so no would be my answer. Anyway, I’ve looked over the internet and found some conflicting answers so I’m asking here.

  1. What components require replacing to use r134a?
  2. What components require a flush?
  3. Does anywhere do a set of all r134a compatible orings?
  4. Anyone know of a place that could remove and flush any old r12 and oil from the system near me?
  5. Where can I get the required parts? Do any parts from later models already running r134a fit without anything much more than bracket fabrication?

Before anyone says it…
No I don’t want to keep r12. I know it is less efficient at cooling but I have easy access to r134a as I work at a dealership so will get a regas of r134a for next to nothing (literally just pay for the actual gas used) as I do it myself. Apart from regassing, I’m not yet fully trained on AC and certainly never learnt about conversion before but otherwise have decent mechanical skill. Main issue with if I need to do a lot of work to the system is I have limited access to the work ramps for my own car. 1 hour at a time at most. Plus my Eunos is my daily so can’t be off the road.

2

I know that typically the R134a runs at higher pressure than R12 so leaks may be more of an issue.

Not sure if these guys are close enough but they are offering the R12 to R134a conversion

3

You’ll need to check that your a/c compressor is still working and that the clutch hasn’t seized, The compressor will probably need new oil, and then all the seals will need replacing (mostly ‘o’ rings) to the 134 compatible seals. Also check the condenser (the a/c/ radiator) as it’s 33 yrs old it’ll probably be either leaking or have most the fins missing. You’ll also need a couple of convertor valves which can be bought on eBay quite cheaply, plus a new drier (the canister that collects any moisture in the system).

There’s a fair few parts to go through but as long as you are methodical you should get it working. A few years ago I collected all the parts to use on my old '91 including a very rare new condenser (LHD as you can’t get RHD) plus a used un-siezed compressor. Never got round to doing it so they probably still lurk in the garage somewhere!

4

Have you used these guys yourself? A little far unless i visit my parents too

5

Thanks. If my compressor is still working, and as long as i flush it properly, will it run on r134a using about 80% of r12 capacity in the system? Some have said you can, other say no if switching to pag oil.

1 Like
6

I am aware of them from other car forums but I have not personally used them.

1 Like
7

Alright. Thank you :+1:

8

There’s an article here: Converting Air Conditioning to R-134

1 Like
9

Thank you :blush: