Big, Big Time Poster
R-12 to R-134a conversion made simple.
Heres how I converted my 89 a/c system from r-12 to r-134a.
Evacuated R-12 and oil.
Added adapter fittings to R-12 lines.
Pulled system into a deep vacuum.
Added oil and r-134a to system(4.24lbs)
Ate a piece of pie while charging....
Blows cold baby!
I work in a shop so this costed merely $20.
Works F'ing Fine!
3 Grand Master
Er... arent you supposed to at least change the receiver/dryer and pressure switch?Originally Posted by aston_jag_tech
Heres how I converted my 89 a/c system from r-12 to r-134a.
Evacuated R-12 and oil.
Added adapter fittings to R-12 lines.
Pulled system into a deep vacuum.
Added oil and r-134a to system(4.24lbs)
Ate a piece of pie while charging....
Blows cold baby!
I work in a shop so this costed merely $20.
Works F'ing Fine!Not to mention all the seals and the hoses. Mind you, at that price you can top it up every week
4 Grand Master
He's a mechanic... Reason for receiver dryer is to capture excess oil and any moisture in the system... but since you vacuum the system for 30 minutes... hardly if any moisture because it boils off under vacuum... so this part is practically 'optional' but is a good practice to change it.
As for the pressure sensor... yes, if there is one for the R134... lower pressure... is better but again... not really needed.
Super Moderator
I did the same 2 years ago with one of these 30-50 $ R12>R134a conversion kits, but also replaced the dryer and the pressure switch. Till now works fine, blows cold, never had to add / charge since then.
Major Contributor
From what I've read before, the reason for changing the dryer lies with the fact that R-12 and R-134 use different desiccants and to avoid introducing any contaminants from the old dryer into the newly recharged system. Hope it works out well for you
Super Moderator
Pressure switch I had to change, because I still had the old one with 3 connectors.
Cars before 2/89 have three pressure switches mounted on the dryer. A high pressure switch, a low pressure switch and an intermittant pressure switch. The updated design only has 1 switch that is used for low and high pressure detection. The intermitant pressure switch will no longer be used.
http://bmwe32.masscom.net/johan/airc...con_R134a.html
Big, Big Time Poster
Right on guys!
Yeah Ill update this thread if I have any issues. Due to my a/c system not having a microfilter I spent a good half hour cleaning all the build up of dirt on the evap.. ewwww
Major Contributor
How did you access the evaporator? I'm thinking of doing this on my car and am wondering if access is the same as the filter-equipped cars.Right on guys!
Yeah Ill update this thread if I have any issues. Due to my a/c system not having a microfilter I spent a good half hour cleaning all the build up of dirt on the evap.. ewwww
4 Grand Master
There is an evaporator cleaner... you inject them through the drain tube while the car is off... it will penetrage the evaporator and heater core with cleaning foam... actually it will fill up the chamber completely.
After 15 minutes or so, you start up the car and AC (fan low) and the condensation will break down the foam and drain out.
Big, Big Time Poster
Yeah that stuff is great I highly recommend that too! Induce the cleaner before the evap and after the blower motor so the foam is pushed through evap....
I used that initially but was curious to see the evap...Picture you are seven again and all you care about is your birthday and the type of cake you love is double fudge choc. cake with heavy choc. frosting and the sensations of jam packing your face with this gooey thick cake blows your mind....well..
...there was heavy choc. cake frosting jammed in the evap! Not as delicious though.
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