Early SW20, what air con gas to use?

[imdying]

Hi,

I've a '90 MR2, non turbo auto, nothing special. When I brought it (during winter), I didn't notice that the aircon didn't work. A hvac mate gave the schrader valve a push, and it was empty. The high and low pressure valves are 3/8" x 24 threaded, so we attached some gas and put 800 grams of R134a into it. Now that all worked out great, nice and cold in the summer heat.

In conversation with a more experienced tech at his work (heat pumps, not car AC), the tech mentioned that seeing as the schrader valves were 3/8" threaded, and not clip on, it was more likely that the original gas would have been R12 instead of R134a. Apparently those fittings are a reasonable indicator. Of course those two gases are compatible (they use different oil), which means I may have the wrong stuff in their. That's no biggy either, as we have some R134a, some R12 (which is illegal now iirc), and some Iceon xxx or some such, which iirc is an R12 replacement.

There is supposed to be a tag on the compressor with the gas type, but stuffed if I can see one.

Long story short, it's easy for us to either change the gas or the oil, we just need to know what it's supposed to take. Sooo, anybody know what an early SW20 MR2 takes from the factory?

[Dell'Orto]

I think most early imports had R12 in them. If it was empty, it shouldnt be too bad to put R134a in it

[blackmk3]

nah nah nah uve put the wrong gas in there, the R12 systems have that shroda fitting and the newer cars <91 have R134a they have a diffrent fitting that u need a special coupling to mate to them, and the oils are diffrent and also the expansion valves, easy option is just to remove the refigerant by getting a professional to reclaim it ... , did i hear a psssssssst? lol neway, you shd also get the system evacuated while there is no gas in there this sucks the system onto a vacume and removes all the air and moisture out of it then refill it with sum r12 if u got some or sp34e or Iceon whatever u have that replaces r12

did u just weigh in the refigerant or use the sight glass?

PS u do need to swap the refigerants as r134a fouls mineral oil real bad and turns it to sludge which will kill ur expansion valve and ur compressor, r134a uses polyolester oils which is synthetic

[vvega]

Hi,

I've a '90 MR2, non turbo auto, nothing special. When I brought it (during winter), I didn't notice that the aircon didn't work. A hvac mate gave the schrader valve a push, and it was empty. The high and low pressure valves are 3/8" x 24 threaded, so we attached some gas and put 800 grams of R134a into it. Now that all worked out great, nice and cold in the summer heat.

In conversation with a more experienced tech at his work (heat pumps, not car AC), the tech mentioned that seeing as the schrader valves were 3/8" threaded, and not clip on, it was more likely that the original gas would have been R12 instead of R134a. Apparently those fittings are a reasonable indicator. Of course those two gases are compatible (they use different oil), which means I may have the wrong stuff in their. That's no biggy either, as we have some R134a, some R12 (which is illegal now iirc), and some Iceon xxx or some such, which iirc is an R12 replacement.

There is supposed to be a tag on the compressor with the gas type, but stuffed if I can see one.

Long story short, it's easy for us to either change the gas or the oil, we just need to know what it's supposed to take. Sooo, anybody know what an early SW20 MR2 takes from the factory?

malcom ???

v

[Akane]

hook us up with some of those old CFC gases aiiight!

[blackmk3]

lol you can just buy drop in replacements for r12

[imdying]

malcom ???v

mom?

Heh, the whole sludge thing was what was making us worried. We've got an evac setup, so we won't be needing to use the big blue decanter in the sky

Weighed in the new gas, vac'd it with a two stager. I'll confirm what gas we used, and drop it if it's 134a.

[imdying]

Thought I'd add what happened here. About 800gm of R134a, worked fantastic. Appears to have a leak though, as the pressure was gone after about a week. Given that it was free to try, it's no biggy, I don't think I'll bother ever fixing it (wifes car).

[Alex B]

There was a recall in the early 90s with this fault, i think its an expansion valve behind the dash, about $120 bucks from revvy i think. The sticker for what gas was in it was on the under side of the bonnet with mine, which i got refilled but still doesn't work...

[Akane]

No, the gases leaked away because the R134a is tiny compared to R12 (smaller molecules), and gets past the fittings and o-rings easily.

If you wanna go full R134a (which is a good idea) you have to retrofit a lot of things, you can either

1) Get a pro to replace all valves and joints and o-rings etc with R134a compatible ones

or 2) Get a 94 MR2 and thief all the aircon stuff on it.

Failing that, best to use the R12 stuff, if you don't wanna use it, give it to me.

[imdying]

I might chuck some uv dye in there at some stage and have a snoop around.

[Bling]

whats ya location? you seem to have mean AC hookups and mines empty, thus need hooking up

[imdying]

I would be reluctant to play with another persons car, as you can see from this thread although I have access to all the right gear, I don't know a whole heap about air conditioning systems in cars (although they're pretty basic from what I can see, especially compared to an office block )

If you've some good working knowledge on carbon fibre and constructing composite components though, you might be able to twist me arm