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How many ounces of R12 in an Esprit? - Interior/Exterior/Lights/Glass/Alarms/ICE/HVAC - The Lotus Forums #ForTheOwners Jump to content

How many ounces of R12 in an Esprit?

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Hi all,

I'm converting from R12 to R134a, for my '89 Esprit.  I can't find the amount of R12 required anywhere.  Not in my manual and there is no sticker on the car anywhere.

From everything I've heard/read, R134A is very sensitive to the amount (by weight) that you put in the system, and you need to multiply the amount of R12 required by a factor to put in precisely the correct amount of R134A.

I am starting with a car that has had no working AC for many years (don't know how many.)  I replaced all the shraeder valves and the dryer as a matter of course, flushed out the system, and then put in one can of R134A so far.  The good news is that the AC immediately started blowing cool air....but not very cold.  But I also know it will take more than one can.  Just don't know how much more to put in.

I know R134A is never going to be as good as the R12, but right now ANYTHING is better than nothing.

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Workshop manual for my 1988 Stevens X180 turbo gives  a charge for refrigerant 12 of 1.4kg (3lbs). 


The quick check procedure using the sight glass advised:

Continuous bubbles -------   system low on charge

Sight glass clear for more than 45 seconds after switching off  before foaming and settling away from glass--------system overcharged

Foams and settles away from sight glass in less than 45 seconds after switching off-------system correctly charged

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Thanks.  That's helpful.

I'm converting to R134A.  There is a rule of thumb that when converting to R134a, you should use approximately 80% of the amount of R12 that you would use.

So that would come to about 40oz of R134A.  I've already put in 36oz and the AC is developing about 35psi pressure on the low side.  The other rule of thumb is that at about  85 to 90F degrees outside, I should be developing closer to 50psi.  I doubt 4 more ounces is going to get me there.  But at least I now know I am pretty close to the correct quantity.

Drove the car about 150 miles today in 90F, very humid weather (Florida) and the AC did manage to keep me comfortable.  But it doesn't blow very cold.  Anything is better than 90F, though!

Edited by twright55
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