Ok so after reading for about 3 hours, I think I need to replace the Accumulator, Oriface tube, and flush the AC lines before putting in 134a. But I keep reading about putting the entire system under vacuum when adding the new refridgerent. And so here are the questions I have: (I would really like to see some picures with arrows, I'm having a hard time grasping these things)

1. Which is the low side port and which is the high side
2. Where exactly is the oriface tube?
3. Can I rent a tool to put a vacuum on the line, and if so where do I hook it up? The low side port?? If so how do you add refridgerent if your using the low side port?
4. How can I visually tell which model I have for a compressor? I.E. has it allready been replaced with the faster 134a compressor?

1-2-3 are really important for me. Please take a second and show me.
Thanks in advance!
-Paul

I do not have any pictures, but it is pretty straight forward.

1. - The low side port is the port that is on the accumulator, and of course the accumulator is the round cylinder shaped thing that sits above the spare. The high side port is the port that is the lowest in the front compartment.

2. - The orifice tube is inside of the small section of hose that sits directly under the accumulator. You have to remove the hose section to get at and and remove the orifice

3. - You can pick up a vacuum pump from Autozone's free tool rental program. They typically want a deposit that you get back when you bring the pump back. However you will probably have to get your own gauge/hose set to hook the pump to the system. The gauge set hooks to the high and low side to read pressures, but you only service thru the system thru the low side. When I vacuum my system, I start with vacuum on both high and low, then after about 5 minutes, I close the vacuum on the high side and continue drawing thru the low side. You can only read the vacuum on the low side. The 134a is serviced thru the low side only by closing the high side on the hose set, then opening the low side. One way to ensure you do not inadvertantly service thru the high side is by taking the hose off the high side service port when servicing.

4. - I will leave the definitive answer for this one to someone else. I normally confuse the two different types of compressors. I believe the 4 cylinders come with the more desirable variable displacement compressors that do not cycle, however from what I've read the variable displacement compressors made for R12 have a control valve inside of it that will not work as good with 134a, so you'd have to install a control valve for 134a to get optimal performance out of it.

Now, I will have to add that if you are really not too sure on how to use a AC gauge hose set, ask for someone to give you a hand that is familiar with how to use it, or just take your car to a shop and have it done. If you do the flush, and accumulator and orifice change yourself, you are going to save youself a few bucks anyway. The set is pretty easy to use, but if you inadvertantly leave the high side open while servicing the system with the engine running, you could explode a can of freon.

I will be in my garage working on my car later today, and if there are not any pics up by then, I will post a few for you.

edit - when you do the conversion, make sure to install the newer 134 type of qucik disconnects on the service ports. They screw onto the schrader valves. If you do not, you will have a hard time servicing it since the 134a hose sets are different than the R12 hose sets.

[This message has been edited by topcat (edited 07-16-2006).]

I just got back from Advance Auto, they do not have the vaccum pieces, so I'll have to contact autozone. I'm going to order a variable size oriface tube, and a new reciever as well. There is a compressor cycle switch on the accumulator! The switch can be replaced with a 134a switch (YAY), I just have to find one of these swtitches as I can't find one within 100 miles at an Advance auto.

Topcat: Your info is REALLY helpful, thank you. So low side is on the reciever and high side is in front of the oriface tube on that pipe. Ok Got it. I also looked up the set of gauges and hoses from an Ampro book at Advance, and they look pricey. I assume that you hook both hoses to the low and high side, and then there is a port on the back side of the gauges that will alow for a vacuum to be applied. I am really thinking now that mabye it would be smart to have someone with some experience to at least pull the vacuum.

Ok here's the thing that is still stumping me; after getting all of the R-12 residuals out (mineral oil, moisture), you would apply the vacuum, and so I'm guessing that you apply the vacuum and then simply quickly disconnect the guage set and the low and high pressure ports will seal holding the vacuum.....right? And then you add the freon + lubricant. Or am I wrong and you add the freon WHILE the gauges are STILL connected to the low end port (hypothetically saying you disconnected from the high side for safety reasons)?

I'm going to risk uaing the DA5 Compressor rather than buying a $200 HR-6, that's alot of money to spend on just a compressor that may cool slightly cooler. Besides with the adjustable oriface tube the system should run much colder at idle speeds anyway. Anyone else feel the same way?

I need pictures now of the actual process: Vacuum lines conected for instance with a vacuum piggybacking.

Does anyone know the right amount of vacuum to put on high - Low sides if I decide I should do this for knowledge's sake.

Thanks!

I'm glad someone started this. I tried to do the conversion using a kit from Advanced Auto (probably the same available from AutoZone) and think I failed miserably.

Haha, you just stick to making those emblems and the keyboard ok

Bump

This link helped me out a lot when I started my conversion. As far as the cycle switch, you do not need to replace it with one for a 134a system. The one on the car will work just fine, and it has an adjustment screw to adjust the cutoff pressure... so I would save my money.

As far as how much vacuum, you need to pull 30" and leave it there for at least 30 minutes. The longer, the better... especially if you used some sort of solvent as a flush agent. When I flushed mine, I held the vacuum for about six hours. And yes, once you remove the gauge set from the schrader valve, the system will hold the vacuum. If it does not then you have a leak that you MUST find and fix.

AC Gauge sets have three hoses.

1. The yellow hose connects to the vacuum source and or the freon source
   
   
2. The blue hose connects to low prssure the schrader valve on the accumulator
   
   
3. The red hose connects to the high pressure port near the orifice tube

To get all the residual out of the system (mineral oil, flush agent, moisture) first you should use some sort of flush agent. You can buy the flush kits at parts stores that work pretty good, but I used regular denatured alcohol. After putting the alcohol in the system, you blow it all out with dry air or nitrogen. I used air. After blowing all the excess flush agent out of the system, add half your oil to the compressor then the other half to your accumulator. You will need about 8 oz of oil

After the flush, connect the hose set to the low side, then connect the yellow hose to the vacuum pump, turn it on and watch the vacuum. You really do not need to hook the red hose up at all for this step. You should be able to get 30 inches, but rememebr that if there is moisture in the system, it will take time for it to boil off, and as it does the vacuum will fluctuate. You want the vacuum to be rock steady before you service the system. After holding a vacuum for at least 30 minutes, remove the yellow hose from the vac pump, then connect your freon can to the yellow hose. An empty system will take almost three whole cans of freon. Add as much freon as the system will take with the engine off. Start the engine and continue to add freon.

=)

Thank you!