Auto A/C question

[ob]

I have a question for all you do-it-your-selfers as to what is required in converting a R-12 85 Toyota A/C to R-134.Here's what I've found out so far.The oils are not compatible between the two and I was told to flush the system to evacuate the R-12 oil from the lines and compressor.I've gotten mixed reviews from some of the local shops as to whether it is necessary to replace the evaporator expansion valve or just use the one that is present in the R-12 system.Any and all thoughts or comments are welcome.Thanks in advance.

 

[SpinnerBait_Nut]

Re: Auto A/C question

OB, all I know is that they sell the kits to convert to R-134 and it don't mention anything about changing the evaporator on the system.<br /><br />Just new style fittings and o-rings, suck/draw the system down good and recharge.

 

[buttonhook]

Re: Auto A/C question

all you do is flush the old and replace it with the new kit those thing work great!! I have changed over 2-3 cars now with it. But you have to drain the system first (you figure out how !)<br />them install the new fiting and follow thw directions with the kit exactly!!

 

[buttonhook]

Re: Auto A/C question

all you do is flush the old and replace it with the new kit those thing work great!! I have changed over 2-3 cars now with it. But you have to drain the system first (you figure out how !)<br />them install the new fiting and follow thw directions with the kit exactly!! <br />Btw<br />it help to have a valve stem tool<br />to drain the !! the low pessure side!!!!!

 

[ehenry]

Re: Auto A/C question

OB, all the jap automakers used ester oil in their compressors. Ester oil will will carry through the system on r134 just as it will on r12. If you have a way of bleeding it down and pulling a vacume on the system you can just dump the r134 in the system. Also you will need a way to tap the r134 cans since they are a different size and are threaded at the top. Get the kit Button Hook is talkin about and you'll be fine.

 

[SlowlySinking]

Re: Auto A/C question

buttonhook, to legally get rid of the R-12 go to an AC shop and offer the R-12 in partial exchange for the 134-a conversion, the pump down is important to reduce the internal pressure so the water vaporizes and is removed, otherwise it mixes with the freon and becomes an acid which eats the system,

 

[buttonhook]

Re: Auto A/C question

i know that. thats why I did want to tell him exactly how to do it(oops it all leaked out). the cars I've worked the system has been busted and the r-12 was gone already or almost all gone.

 

[rwise]

Re: Auto A/C question

ob<br />It mat not be mandatory to replace the evaporator expansion valve, but it will work better with the one for the 134a. It is a must to vacum the system down, it will last longer and blow colder. R134a is not going to get as cold as R12 did. <br />Richard<br /><br />ps. we don't want to here you let it (the R12) out in the air etc

 

[buttonhook]

Re: Auto A/C question

let me say something. I wouldn't convert an existing r-12 to r-134 if the system is working. And as far as lefting r-12 loose in the air. it happens all the time(car wrecks,etc.) so I think if a little gets out then no problem. just don't make a habit out of it and don't do it if not ness. but I've had a couple of mustangs and the low pressure hose rubs in two on the intake manifold *poof* there goes all the r-12. so I've let out more than he would if he worked on the unit himself just by poor design.

 

[ob]

Re: Auto A/C question

Thanks for the info guys.Interesting tidbit about the ester oil in the jap R-12 systems, efhenry.The reason I have decided to convert is probably the same reason that most do-it-your -selfers have .R-12 is not obtainable without a license and its modern day cost is outrageous.Just recently had to replace the reciever/drier due to an external corrosion leak and figured I'd convert to R134 when recharging.I've got a set of nice manifold guages and have the high and low side fittings to vacuum system and recharge.I think I'll try using the existing oil in system and see how she works.Thanks for all the input and I'll post back with the results.

 

[buttonhook]

Re: Auto A/C question

if you buy the kit it comes with the 1can of oil and 3 cans of 134, the valves, and the tools to install all for like $35 I think

 

[ob]

Re: Auto A/C question

Thanks for the info buttonhook.I recently aquired a R134 system high and low side tap valve kit to vacuum and charge my daughters wrecked Isuzu.That was more than I wanted to know about Isuzus ,but it's down to the easy stuff like fenders and bumpers now.I've also got 3 cans of R134 in the garage ,so I'll give it a shot after I borrow Aut-Zones vacuum pump.Thanks again.

 

[ehenry]

Re: Auto A/C question

Also, be advised that the kit valves that screw down on to your high and low pressure sides have been tendancy to leak. Excersise care in putting them on so you don't cut an o-ring or by some wierd fluke get it cross threaded. A buddy of mine converted his Chevy truck and the system leaked where the new valves went on. He just took them off to keep from loosing his charge. He puts the low side on when he needs to add a can.

 

[ob]

Re: Auto A/C question

10-4 efhenry.

 

[Skinnywater]

Re: Auto A/C question

You can try whatever you want but there is only one way to do it correctly. <br />All black orings have to be replaced with green ones. The compressor has to be removed and all oil drained from it. The expansion valve and filter/drier should be replaced (your replacing the orings anyhow.) The remaining hoses, condensor and evaporator should be filled with denatured alcohol and blown out with compressed air. The only oil that works best by trial and experience is PAG oil. This is the complete conversion as per Mercedes Benz and BMW. I've converted well over 300 vehicles and have converted 4-6 in the past 30 days. <br /><br />Ester oil by my experience is a bad move. It doesn't allow the heat to dump in the condensor very well and high side pressures are excessive.<br /><br />Contrary to what may be believed a properly converted system will perform noticeably better with R134a then R12. <br /><br />The above is a lot of work. However, the temps around here are typically over 100f and I have to guarenty my work for a minimum of a year. Much longer is expected.

 

[Gold Bear]

Re: Auto A/C question

ob<br /><br />I agree with Skinnywater.<br /><br />I have converted a 1980 model and a 1990 Toyota pick-up truck to 134a.<br /><br />I removed everything and flushed each piece, then replaced the "O-rings" with green ones. Additionally, I used PAG oil and a new dryer.<br /><br />The 1980 model AC worked fine for the last two years I owned it. The 1990 model which I still own has not had any problems in the three years since I converted it. <br /><br />On the 1990 model the vent temp is approx 45 degrees on the hottest summer day here in Mobile.<br /><br />I believe that Toyota used the same expansion valve when they first changed over to 134a. I had the same concern as you, so I checked the part number.<br /><br />Convert it and enjoy!<br /><br />Regards, <br />Gold Bear

 

[petryshyn]

Re: Auto A/C question

OB<br />If I remember right, Toyota a/c hoses were not compatable with R-134a (no neoprene liner)till after 1986. Better check with the dealer. You may need new upgraded hoses. Go with POE oil and use the original expansion valve. Change out the receiver dryer, as Toyota's have problems with the desicant deteriorating with age and distroying the pump.

 

[ob]

Re: Auto A/C question

I've changed the hoses out with ones I got from a local auto A/C shop in town.Haven't removed the compressor yet to drain the oil or flush system.I plan to do that this evening.What is the difference between the PAG oil and the POE oil?Will one mix better with the R134 for system distribution?

 

[petryshyn]

Re: Auto A/C question

PAG has smaller molecules which appear to carry better with R-134a. POE has better lubrication qualities. Some pumps will fail with PAG. (R-5 type) PAG doesn't mix well with your existing mineral oil. The OEM GM and OEM Chrysler retro kits that we have here use POE. We use POE exclusively in retro's. If you go to PAG, drain and flush the compressor, evaporator and condenser as Skinnywater says. Up here, in our world, POE is the standard for retro's.

 

[ob]

Re: Auto A/C question

Shematic,If I use POE oil to boost what the system may lack is it necessary to completely purge all of the mineral oil from system?Should I remove what oil is now in the system and not worry about residual mineral oil as the POE oil will be compatible with it?