chipschoch

My son recently got a 93 SC300 and we found out that the AC Compressor is ceased up. I ordered a rebuilt from ACKits.com and also ordered a new receiver drier. I am looking for some instructions on the replacement procedure. I located the drier, but it is not clear how to access it to replace it.

Also, I think I can stumble through replacing the compressor but if there is any experience out there that would be willing to outline the steps I would really appreciate it. Otherwise, I am sure I will end up removing a bunch of stuff I don't need to.

One other thing. Are you supposed to use any sort of gasket sealer when you attach the hose manifold to the compressor. I am guessing on how to refer to it based on the pictures, as I have not received the compressor yet.

Any help will be sincerely appreciated.

Thanks

O. L. T.

iTrader: (17)

Steelwheel

I would recommend poking around http://www.autoacforum.com/ for general instructions on mobile a/c along with information from a CL search concerning SC300 a/c stuff. Since the compressor froze, you may want to make sure your system is clean (check the above link for all that info) before putting back together.

A few things I found doing a 93 SC400 (not sure if it is similar to your SC300) you might want to consider:

- get a Tech manual (or the Lexus TSB) describing how to change it over to R134a (original 93 was R12).

- use the toyota part o-rings (recommended in the tech manual/tsb) and coat them with mineral oil or Nylog. The kits with generic a/c o-rings may work, but expect them to leak if not perfect.

- charge by weight and use the right amount and type of oil. Use vacuum pump to check for leaks and recharge.

- I chose to run a blended hydrocarbon refrigerant, most just charge r134a or R12 back in which should also do a good job. Just found the propane/butane chills well and causes the compressor to be almost silent, so have been very happy with it.

Good Luck,

Tim

chipschoch

Thanks. Someone had already converted to 134 and I suspect that it is part of what caused the problem to begin with. They probably idn'y change the oil in the pump or something like that.

I have ordered a new expansion valve. I also plan to fill it with Enviro-Safe ES-12a refrigerant, which I came across while researching AC on this site. It is supposed to perform much better, especially considering that the car still has the R12 condenser and evaporator.

I am mostly looking for tips on what to remove to get the compressor and drier out with the least amount of extra removal. I got a procedure for the expansion valve removal from the Lexus dealer, so that should help, although every time I have had to do anything under the dash in any car I have had, I end up breaking something. There always seems to be one fastener that gets overlooked.

Once I get all the parts replaced I plan on taking into a shop to evac and charge as I don't have the equipment. Not to mention I have never done it and don't really know ****** about A/C. It is my 16 year olds car and he saved up his money and bought in on EBay. The guy said the AC just needed charging. He lied. I just can't see paying $1200-$1500 to fix the AC on a $3000 car, so we are gonna try to do it ourselves for more like $400. Perhaps it is a bit ambitious, as I am not a mechanic, but we're giving it a shot.

Steelwheel

Envirosafe 12a is a hydrocarbon blend also (like the Duracool that has done very well for me).

Make sure you know that they have different charging instructions compared to 134a or 12 (non-blends). Duracool does not recommend charging with a vacuum over 10".

Blends (which have many positives) have drawbacks also:

-You can't just "top off" a blend if you have a slow leak, since blends may only leak out one of it's many gasses leaving a wrong percentage of gas that may cause problems. Basically if you develop a leak, you will need to evacuate and charge all new again.

-They may take a few minutes longer to get cool since it takes a few minutes for them to get mixed up.

You should be able to find all the removal instructions for the components in a tech manual like was mentioned on the first reply. Unless you find a DIY posted here, it may be easier to just find a good manual (another search on here or Ebay, etc.)

Regards,

Tim

red04r1

If the freeon or R134 is LOW the compressor doesnt engage... I thought I had a bad compressor as well, but it was just low.

chipschoch

I took it into the shop and the guy said it was frozen up and needed replacing. He is a local guy that I have had good luck with so I see no reason to doubt him. Anyway, I have a rebuilt compressor so it's going in.

I got a procedure from the Lexus dealer on how to remove the evaporator, because the expansion vale is located there, and it said in that procedure that if you are replacing the evaporator you need to put some oil in it. Now I am planning on flushing it when I have it out. My question is, since I am replacing the compressor, which come with a charge of oil in it, do I still need to put some oil in the evaporator or are they assuming that I simply need to replace the oil that was pumped out of the compressor under normal use. It's not clear to me and when I called the Lexus dealer to ask them they gave me the run around. Any ideas on this?

Steelwheel

I just did something similar to what you are about to do, so I'll try to explain how I thought it through.

Using Lexus TSB AC001-98 April 3, 1998 (converting r12 to r134a), along with the FSM.

TSB gives the retrokit and oil amounts along with the procedure. It is the same for your SC300 as the SC400, so it should work for you.

They recommend when converting from 12 to 134a, you add 150cc of ND8 oil or equivalent (PAG oil that Lexus tested and made sure was okay to mix with the existing mineral oil, note that all PAG oils may not be the same, some are able to mix with mineral without bad side effects). This 150cc is added to the system on top of the existing mineral oil from the old r12 system.

It recommends adding half of the 150cc to the receiver and the other half by direct charging.

There is another section in the normal manual (FSM) that gives an estimate if you are just changing out components. These are replacement volumes for using mineral oil (should be close if using another type)

Receiver: 20cc or .7oz
Condenser: 40-50cc or 1.4-1.7 oz.
Evaporator: Same as condensor volumes.

I would guess the total charge for the system might be 150cc + the 120cc above. If you are flushing, it won't hurt to put a little more in it.

Also, the r134a charge for 93 sc300 is 900g in case you need to cross it to the ES 12a

All this information is available via easily accessable digital manuals (believe they are still easy to get and reasonably priced, they were when I got one a while back)

Regards,

Tim

chipschoch

Thanks for you info.

Today I swapped out the compressor, receiver/drier and expansion valve. I did not flush it because the guy from ACKits, where I got the compressor said it probably was not necessary and I could end up not getting all the flushing agent out. The old expansion valve did not have any trace of debris in it so chances are there was nothing to flush. I blew air through the evaporator and nothing came out. Things went pretty smooth and I got it all back together with no major screw-ups. I then charge it with ES-12A according to what the Enviro-safe guy told me, that is with zero vacuum add refrigerant charge to between 32-38 psi. So, I got 35 psi on it and it cools... a bit. I'm kind of disappointed. I thought I would be getting the big freeze, but no. The system is definitely working as I could turn the ac off and feel the air temp then turn it on and could feel the temperature change. The compressor engages and pumps away. It just doesn't get that cool. Any suggestions as to what may be the cause of this?

I was told by my mechanic that fixing the compressor would cost alot and would not get that cold, (because it was originally an R-12 system converted to 134) that is why I did it myself. And reading through the forums I was convinced that by using a hydrocarbon refrigerant I would get the cold I wanted. Was my mechanic right? Am I stuck with a system that only marginally cools?

pinto096

they make an r-12 replacement called freeze r-12 its an easy substitute for r-12 they sell it at auto zone but it goes as fast as it comes out on the shelf you may want to google it and see if you can get it on the internet dosent require am mv608

Steelwheel

Good questions. The FSM has you rev the engine up to 2000 Rpm and check pressure. Note that at 2000 rpm the compressor is more efficient and will cause the inlet pressure to drop in a fully charged SC from 35-40 psi @ 600 rpm +/- to around the 22 psi @ 2000rpm (R12 pressure which is pretty close, but maybe just slightly higher than the hydrocarbon propane/butane pressures). The Lexus FSM says charge it from 22 - 27 psi or something like that at 2000rpm and 80F outside. Remember if you are charging by pressure, the temp outside going up or down from the normal will change the pressure quite a bit. This is why most will recommend charging by weight. For a car, I guess it is okay to just wing it a little if you must.

I believe it was just around 2 cans (12 oz of Duracool) to equal normal charge weight of the 900 grams. You may want to make sure the volume you got was close to the 900 gram equivalent. If not, I would make it.

I noticed also that I had to warm the last few ounces to get it in. It really did not want to go in without a little help.

Here is another thing, make sure your evaporator coil and condenser coil are cleaned as good as you can. This will help with efficiency.

With all that done, this might be the most important thing to note. Using a blend can take several minutes for the stratified gases to become homogenous (12 and 134a do not require mixing). Mine has a delay before it really starts cooling compared to the old R134a system. Once mixed, it seems better and colder (I've gotten so cold on 100F days that I have to turn it off on the highway) than the R134a ever was.

At idle rpms and sitting still with less air across condenser, mine seems to just maintain the temperature, but not cool as well at the stop as the old R134a system. This does not affect me once it is cooled down.

These are my experiences and they may not be totally due to the blend. For now though it is doing fine, just has a few quirks compared to when running the 12 or 134a stuff.

I'm keeping the propane since it is quieter and overall cooler. The best thing about the change has been the compressor is totally silent. My other two newer toyota compressors are noticeably louder. It also gets the same gas mileage with or without the AC running. Seems like it does not use much HP to run it.

Another great thing about running the AC on propane... you can use the leftover to grill a steak if you ever total out the car.

Good Luck,

Tim

Steelwheel

I've heard good things from others using Freeze 12. It is a blend of 80% R-134a and 20% HCFC-142b. It is like running R-134a with enough 142b to be able to pick up the mineral oil that use to run in the old R12 systems, thus you don't have to convert like a normal 134a conversion. You still have the disadvantage of running a blend which is you can not "top off" a slow leaking system like you could with the old r12 or the r134a systems.

Seriously don't think switching from ES 12a to other blends will make much difference since it should perform as well as other refrigerants.

Duracool seemed to have the best quality control of the 12a suppliers. I considered ES, and have not heard anything negative about them. Have read from some forums that the ES industrial 12a has been favored for a while over the regular 12a. The only two companies that I felt comfortable with buying a hydrocarbon refrigerant from was RedTek and Duracool. Chose Duracool since it has a nasty smell when leaking, Redtek smelled like pine. The other producers did not have convincing quality.

A big company in Arkansas that I personally deal with uses Duracool with very positive results in the past several years.

Regards,

Tim

neodymium

Well, I was going to buy some Duracool based on Steelwheels experience with it until I did a little research and found this: http://www.epa.gov/ozone/snap/refrig...tml#conditions
It is listed as an unacceptable sub for r-12 because: Flammable blend of hydrocarbons; insufficient data to demonstrate safety
Is Duracool better than freeze12? Maybe I can just use regular r-12. It sells on the internet for $30/12 oz can.

Steelwheel

Correct, I was also well aware of this before purchasing and using. It replaced R134a (not R12), so was not affected by this policy. If you research more, you will find it is illegal to run hydrocarbon refrigerants in mobile vehicles in several states so I would not run it in any of those. This was brought about by an obvious propaganda film that some goofball released several cans of HC 12a in a car then caught it on fire, lol. This was a pretty funny video and was only done since the people against HC 12a can't find one single incident related to real life hydrocarbon refrigerant (when used properly).

I'm not gonna debate whether or not putting 12 oz of hydrocarbon based material will cause a tremendous danger, but there is no record of anyone harmed by using this in their car. Out of millions of cars and billions of miles driving with it, not even a single incident.

Personally I would recommend R134a or even better R12 (easier to get now that R134a is expensive) for most people because they work fine and there is nothing wrong with them. Some of us just like to be different.

I will continue to use Duracool in all my stuff since it is really quiet and so cool. Mostly I like living dangerously. Heck, you won't believe this but I carry a tank right behind the back seat in an SC400 that holds 20 gallons of hydrocarbons. Wonder if the EPA has a policy about that 20 gallon gas tank?

BTW, if you bleed your R12 or R134a refrigerant (which is mixed with oil... go figure), it should carry a flame as good as Duracool. If you burn R12 or R134a, they also give the benefit of putting out gases that cause cancer and instant death in small enough realistic percentages. You will not find these side affects using propane. As a matter of fact, you could light your grill using oil and R12 much like you would propane. But if you breathed the fumes, you would not be alive to eat that steak. Also smoking a cigarette around a leaking Freon system will cause super deadly gases to be inhaled.

Good Luck,

Tim