Toyota Nation Forum banner

1 - 9 of 9 Posts

·
Registered
Joined
·
1,847 Posts
Discussion Starter #1 (Edited)
just buttoned up my head gasket/timing belt oil seal replacement and fitted a newer blower motor when AC compressor started to seize, looked into replacement and am planning on the following:

New Denso R12 compressor/clutch $180 off ebay
New Denso drier $20

will follow excellent advice here (http://www.toyotanation.com/forum/155-2nd-generation-2000-2004/408342-terrible-screeching-noise-when-c-trying-run.html#post3816113) to flush whole system and blow clean

will find shop willing to deal with 1kg R12 removal (they should pay me!) and pull a high vacuum after I flush system.

Am going with so called ester (POE) oil lube after a bit of research. Found a paper entitled " A tribological study of refrigeration oils under HFC-134a environment..." which actually has...gasp! REAL SCIENCE!
google link:https://docs.google.com/viewer?a=v&q=cache:uumNHyxUt1YJ:www.ewp.rpi.edu/hartford/~huntek2/proj/Resources%20(previous%20deliverables-Resources)/Articles-Publications%20Cole%20Library/tribological%20study%20of%20ref%20oils%20in%20134a%20env.pdf+tribological+134a&hl=en&gl=us&pid=bl&srcid=ADGEEShGWLAg7S1vQGhjKJ3s027kgpqS-qZzvKQbIU9S__PtdDoXn49MYgk1s1pLAydz_1ENeqTV9u14ITZuyxdGUJwU4VMyZpNGTcNsZe87d7FqKinzEC6WTeXBD7ODfpp4rpivS5Cu&sig=AHIEtbS4DF4pv5A9C32ZMfo4ZvQks8Hx4g

It shows that:
1 PAG oils are TERRIBLE lubricants
2 ester oils are excellent lubricants
3 o-ring material (and metals too) are impacted exactly the same by PAG/POE; with viton, silicone and turcon all unaffected by PAG and POE. Only straight rubber o rings are trashed by BOTH PAG and POE!

Will have 1 can r134a + UV dye and 2 w/out. If o rings need replacement I'll find out after r134a fill and will use HNBR or "super neoprene" units Will also pull valve cores and add new valves and label (some shops sell "pro level AC valve core pulling tools" for +$50! LOLOLOL std $2 schrader valve core tool works fine!)

Wish me luck!

Ted

1993 Camry Wagon 5S-FE auto 279k
 

·
Registered
Joined
·
1,847 Posts
Discussion Starter #2 (Edited)
no shop will pull the R12 but since I am in enviro conscious PDX I will keep looking and not vent to atmosphere

Autozone no longer has lender vacuum pumps...

but I can rent a big 150psi gasoline compressor nearby and mate to this unit from harbor freight


which should do 29" vac. for $40 BUT ITS LOUD AS HELL ;)
am concerned that exact (R12) Denso dryer I bought is silicon desiccant based not molecular sieve favored for r134a, so will buy compatible dryer from NAPA

flushing is six of one half dozen of another, better to have less oil to settle out into system and screw with heat exchange BUT quite bad to have residual solvent present

Interdynamics sells a diluted ester oil based FLUSH, which may be a good idea as it should maximize mineral oil removal.

R134a to R12 ratios are about 80% wt ratio R134a, by GM (and others) formula, so about 28oz R134a = 1kg R12

Ester oil NOT combined with R134a charge is best idea so oil can be split to several locations in system
 

·
Registered
Joined
·
1,847 Posts
Discussion Starter #3 (Edited)
Residual R134a immiscible mineral oil left in the system will "settle" into places you'd like good heat exchange and hurt performance. Most modern AC flushes have very low vapor pressures (VP) and high BP, so they are removed from the system VERY slowly using airflow and vacuum. HCFC-141b has been banned due to ozone depletion and the main replacement (commercially) is Genesolv SF by Honeywell (HFC-245fa) which is a decent solvent with a pretty low VP.

Consumer flushes are sometimes diluted oil, like Interdynamics Ester flush, or hydrocarbons plus d-limonene (usually ~9:1) The solvents are pretty high VP and remove well but d-limonene has the BP of decane (176C) and a low VP. It cleans well BUT it would be better to flush and then chase with a few volumes of SOLVENT ONLY to remove the d-limonene. Then flow clean dry air for 30min and pull a hard vacuum until system is clean and dry.

Note that vacuum pumps are not BLACK HOLES, what you pull off goes straight into the pump oil unless you have sophisticated temperature and chemical/physical traps, which few AC oil vac pumps have. Add a solvent with appreciable VP and your oil pump will NEVER go low again; you need fresh oil and A FLUSH, or a new pump as countless oil vac pumps have been trashed by condensed corrosive fluids.

Viton is said to NOT be compatible with refrigerants and although Kalrez ($$) likely is, its best to go with green HBNR or so called "super neoprene" o-ring materials.

here is some good info
http://www.fordforumsonline.com/forum/attachments/heating-air-conditioning-cooling-systems/546d1273287761-ford-ac-charts-information-miscellaneous-automotive-hvac-information.pdf

although he's a bit off on POE vs PAG lubricity from my other readings.

see also
http://www.e38.org/pparish/flushing.htm
 

·
Registered
Joined
·
1,847 Posts
Discussion Starter #4 (Edited)
AC relay substitute Panasonic CBAF-R-12v, 40A with RF suppressing resistor, flux sealed and only $5 at Mouser. Doesn't have skirt, should pop right in.
70A versions are available but you'd have to cut/grind down power contacts to fit!

Ended up buying high temp version without resistor parallel to coil, (which original doesn't have) Mouser CB1A-T-12V, 40A and good to 125C ($7.72)
Vanilla Panasonic 40A relay is only $3.55! CB1A-12V
 

·
Registered
Joined
·
1,847 Posts
Discussion Starter #5 (Edited)
dryer for R134a has a different placement of guide pin holes than old silica based R12 dryer, you have to drill new holes! Swapped out old red Toy R12 o -rings for new green R134a o-rings, kept the old o-rings and will see how they do with ester oil, although I plan on replacing ALL o-rings with greenies. There is a video online which shows how simple it is to pull evaporator and valve,
http://youtu.be/RkKry31lk1E
WITHOUT PULLING ENTIRE DASH LOLO
http://youtu.be/9knIfeNgHR0

all o-rings are accessible without pulling dash, draining radiator etc etc HALLELUJAH!

McMaster Carr has green HNBR O-rings cheap, it technically hydrogenated nitrile butadiene rubber (-40° to +300° F) a higher temp version of crappy old BUNA-N, nitrile butadiene rubber (-35° to +250° F), next best is neoprene (-65° to +275° F)
O-ring lube can be POE or PAG but it absorbs H2O from the air, so many use mineral oil, silicone grease or Nylog Blue to lube o-rings

Santech makes compressor parts and has a decent oring primer here
http://www.santech.com/images/pdfs/TD931101.pdf
 

·
Super Moderator
Joined
·
12,791 Posts
Lots of good info in this tedmich! Thinkin' I'll sticky this later when I've got more time.
 

·
Registered
Joined
·
1,847 Posts
Discussion Starter #7 (Edited)
R12 to R134a drier

The drier accumulator of the R134s systems uses molecular sieves which work much better to dry R134a than does the old desiccant material (silica gel as seen in old "do not eat" packets)

So converting R12 to R134a should mean fitting the newer (post 1994) Denso dryer/accumulator, but the guide pins on the lines do not match up. They were designed to stop putting the "wrong" driers on the "wrong" systems. The attached file includes a template which can be attached to the new R134a (the UP image on the left) and the new hole about 3.2mm x 8mm need to be carefully drilled (to avoid piercing the canister top!) The X are pretty close but using a 3.5mm bit will be a safety measure so they fully fit. I sprayed the blank back of the cut out left image with contact cement, and stuck it to the new drier, using the lines to match up, then drill on a drill press. Seal up right after, with tape, but the paper also helps avoiding Al shards falling into the drier. Don't forget a good amount of oil, evac and recharge.

https://drive.google.com/file/d/0Bx4YBDBg2bqPT2diU0k5Y1ZkT2M/edit?usp=sharing
 

·
Super Moderator
Joined
·
12,791 Posts
Hey tedmich - I merged your thread with the template link in it with your previous R12 to R134a conversion thread to get all the info in one place.
 
1 - 9 of 9 Posts
Top