Lets start a thread as a repository of information related to R-134a in our third gens. There are a lot of tid bits of information in other threads related to this topic of converting over but its very scattered and there is a lot of back and forth over some issues.

Some issues I would like clarification on (for starters):

Is there a considerable temperature drop with a regular orifice tube versus a variable orifice tube?

What exactly needs to be changed when converting over to R-134a in order to achieve optimal cooling in extreme weather environments (Texas, Arizona, etc)?

If you buy a new condenser, is it designed for R-134a or is it just a replacement part?

What interchange parts from other GM cars can we use to increase the efficiency of the A/C system?

PAG or Ester Oil?

Also, some of you all are professionals in this field and any tips you want to lend would greatly be appreciated.

some useful links:

General Retrofit guide
https://www.thirdgen.org/retrofitac

R-12 vs R-134a debate
https://www.thirdgen.org/forums/cool...r12-r134a.html
https://www.thirdgen.org/forums/cool...-recharge.html

 

Is there a considerable temperature drop with a regular orifice tube versus a variable orifice tube?
---The biggest temp drops come from dry climates (AZ, NV). In humid climates, the temp drop won't happen as much. But humid climates will benefit from better dehumidification (which is what slows down the amount of temp drop in the first place)


What exactly needs to be changed when converting over to R-134a in order to achieve optimal cooling in extreme weather environments (Texas, Arizona, etc)?
---Condenser! Parallel flow is the best. Visteon sells a direct fit 6mm condenser for our cars. Saves having to get new lines made to fit. Either is better than the stock tube and fin style condenser our cars came with.

Need to lower the low pressure cycle switch (located on the accumulator. Has the 2 prong plug on it. Turn the tiny screw in it about 1/4th to the left)


If you buy a new condenser, is it designed for R-134a or is it just a replacement part?
---Replacement. R-134a cars due to their inefficient refrigerant have better style condensers (parallel flow, 6 mm, piccolo, serpentine) from the factory than old R-12 cars did (tube & fin). But any style will work with any refrigerant. It's just a matter of performance. The very earliest R-134a cars (1993'ish models) had terrible performance. Today, cars are better in that sense.

What interchange parts from other GM cars can we use to increase the efficiency of the A/C system?
---Nothing in particular I can think of. Better radiator fans will help. A good shape air dam helps.

I'd go with a CryoChem "Tune Air" can for an R-134a car. Old mineral oil cars can boil the moisture out with a vacuum pump. But with PAG/POE, the oils will boil before all the moisture can be boiled out. Combined with the PAG/POE oils themselves absorbing more moisture than mineral oil does, you have a situation where the system will never truly be dry. The moisture leads to acid/corrosion/evaporator leaks, and generally headaches in the future. The Tune Air drops your system down to 0 ppm moisture (new accumulator is recommended to be installed first). Thus you have a system that should stay ultra dry for a long time. Especially if used with their Cryo-silane product (prevents leaks). You will need an EPA 609 certification to buy this stuff. As a side benefit, the mere install of the 4 oz can of Tune Air should drop your duct temps by 5-9°F.

PAG or Ester Oil?
--- Six and one half dozen. PAG oil is about 1,000x more moisture absorbing than R-12's mineral oil. POE is about 100x more moisture absorbing. This would mean that POE is better. On the other hand, POE can have troubles with foaming in converted systems. Most people recommend PAG. POE will work in most of the blend alternatives. PAG won't. PAG in any refrigerant that is an HCFC will die in short order.

The R-12 to R-134a conversion is controversial on this message board. The people who like it and say it works well tend to live in northern states where the summers are milder and/or drier. The people who say the conversions aren't worth a darn tend to be in the desert states where it's 100°+ all summer or in the hot/humid states (deep south etc)

 

Thanks Reid, that is some good information right there.

Do you have a part# or information on where to buy the Visteon heat exchanger? I see them for the 4th gens but am having trouble finding them for the 3rd gens.

Edit: Looks like I spoke too soon, Advance Auto Parts actually sells them.

Visteon Part#2092

 

Would using that condenser change the amount of gas that is required for a full charge?

IF you change the setting of the low side switch at what PSI roughly would that shut of compressor off at?

 

hey reid

have you ever made any lines using aeroquip fittings and hoses?

http://www.aeroquip.cc/

Im wondering if using their tool and fittings i could build my own lines and use a parallel flow condensor.

 

Stock (I think) is around 26 psi. Turning it down to about 22 psi should do the trick for R-134a. Won't do you any difference when it's crazy hot outside since the car probably wouldn't cycle anyways. But for the majority of the time it will help. If you're getting coil icing, you'll notice a reduction in air flow coming out the ducts. In that case, turn the pressure switch up a tad.

The refrigerant capacity would change slightly. How much? Not sure. Would have to check psi levels to get a good feel for it.

Never used anything like that. My thoughts on condensers for our cars is if it isn't broke, don't fix it. If I had a full size pickup truck (or something with a lot of room to maneuver in there) I might throw around the idea of something like the above.

One of the best things to do to help comfort is some good high quality tint for a vehicle. Interior temps can drop by 20-30°F quite easily with tint.

 

Reid Fleming,

On your GTA when it has a full charge on R-134A and the cars is not running what is the Neutral presure that you would see? I am having a hard time out here trying of figure out what i should be looking for in my 89 RS. I bought three 12 OZ cans and put the first two in no problem but that last one i was kind of uncertain about. I didn't know where to go to buy a scale so i had to just guess it. I think i put around 6 Oz on the last can plus the other two for ~32 OZ. My compressor doesn't turn off but it was 106 outside today so i don't know if that was the reason. Any how the high side with compressor running is at 245ish and my low side is around 30 to 40psi. When i turn the car off and let everything neutralize both sides go to 70psi. Not sure if that is what it should be and how much that number matters.

 

Just to add to this thread:

Many people replace the stock GM White .72" orifice tube for either a Ford Blue .67" or a Ford Red .62" orifice tube to increase the efficiency of the system when converting to R-134a.

I recently flushed my system, replaced the R4 compressor with a reman, installed new o-rings with Nylog at each fitting, replaced the evaporator and liquid line and installed a Ford Blue orifice tube.

After vacuuming the system, I added just about 40 ounces of refrigerant and on a 86°F ambient day, saw vent temps of 42°-44° degrees at idle and cruising around. I forgot which thread I picked up the bit about Nylog on, but it was certainly worth it. It seemed to make installing o-rings and getting them to seal properly a lot easier.

I really would like to install a parallel flow condenser as well to see if I could get the vent temps to drop even more. I have not modded the recirculation door yet, but have included the thread below for anyone wanting to try to drop the vent temps even more.

A thread about the recirculation door staying partially open:
https://www.thirdgen.org/forums/cool...say-r134a.html