V6UnderPressure

iTrader: (1)

Anyone know what is involved in converting our cars to 134? Is it a do it yourself thing or should a shop do it. The charge in my system finally has given up and I want to get it converted but have no clue as to what is involved. What should it cost for a shop to do vs myself, time etc. Thanks in advance.

T/A

I'm not sure what it'd cost, but i know you must do a full flush, then replace the O-rings and accumulator.

sofakingdom

iTrader: (1)

It's REAL tough to get the old oil all cleaned out of the compressor, which MUST BE done, as the old R-12 oil is incompatible with 134 and will destroy the system if any is left in it. Best to convert & replace at the same time. Personally I've never had any trouble with any decent brand of new one; no need to seek out the OEM brand or whatever.

Consider replacing the rubber part of the lines as well; they often leak, and now's the time. Mess with it once, make it COMPLETELY PERFECT, don't have to touch it again for years. The line is specialized: it's got a solid plastic lining (which is why it's called "barrier hose"), sizes are 11/32" and 5/8" but nowadays they use metric equivalents alot of the time. The hose clamps are MUCH heavier-duty than regular heater hose ones or the like, DO NOT EVEN BOTHER ATTEMPTING to use the ones hanging in the cooling system aisle.

Make DOUBLE DAMN SURE your cooling system, and especially the fan, works right. The car should be capable of sitting still running for hours at a time without THE SLIGHTEST hint of malfunction of any kind, like it did when new; if it can't, then it will be IMPOSSIBLE to drive in city traffic with the A/C running. If you have an electric fan, verify that it comes on when it's supposed to, and blows strong. If you have a clutch fan, just replace the clutch, with a "thermostatic" (more expensive) one, NOT a "centrifugal" (cheeeeeeper) one. Put in a new radiator cap. Get the cooling system operating 100% RIGHT, to factory specs. Not, "I want my temp to always be 180" or similar uneducated drivel; with a clutch fan it should run at around 200 - 210° sitting idling, and with an electric, the fan should come on at around 230° and shut off at around 210°, and do that over and over and over, until the car runs out of gas. Don't waste your time on A/C until the cooling system is PERFECT.

Get the red or orange Frod orifice tube from the mid 90s; its properties happen to be more suitable to a GM R-12 system running R-134a than any of the various GM ones that fit. Something like for about a 96 Crown Vic.

Disassemble the system completely. Remove the lines from the vehicle. Pull out the old OT. Pour a few ounces of a 100% volatile residue-free solvent such as lacquer thinner, acetone, MEK, denatured alcohol, methanol, or (gasp!) A/C flush - NOT gasoline, brake parts cleaner, or most carb cleaners - into the evaporator and condenser. Blow it through with compressed air, with rags wrapped securely around the ends of the hoses. Repeat a few times until it comes out absolutely clean (use a clean white rag). Be careful not to get it on painted parts like fenders. Flush out the metal lines similarly before assembling the new rubber sections to them.

Pour about 2 - 3 oz of new PAG oil (use a thinner kind, not the "150"... "100" is about right) into the accumulator before putting the lines on, and pour about 3 oz of it into the suction (intake) port of the comp (the one that lines up with the large line). Rotate the comp a couple of times by hand.

Install the new comp, accumulator, and OT. Replace all the O-rings with the newer green ones, lube them with clean new oil as you put them on. Install the lines, belt, and wiring.

Hook up your vacuum pump. Draw the system down to a hard vacuum. Let the pump run a half-hour or so. Close the valve and turn it off. Wait another half-hour; verify that the vacuum stays within ½" of mercury (about ¼ psi) of what it was with the pump running. If it doesn't hold vacuum, it won't hold refrigerant either; so fix any leaks now. Repeat the vacuum thing until it satisfies the requirement. Do not bother to proceed until it does.

Add a can of R-134 (turn the can upside down). Start the engine and turn on the A/C to the highest fan setting. It should come on for a few seconds, then shut off, and begin short-cycling. Close the valve and remove the can while it's running, not while it's shut off. Add 2 more cans; it should quit cycling and run constantly, if the ambient temp is above 60° or so.

The accumulator and the large line should be very cold to the touch, and wet with condensation but not frosted. The hot gas line (from comp to condenser) should be too hot to touch. The liquid line (from condenser to evaporator) should be within a few degrees of ambient. The air coming out the vents should be around 40 - 45° cooler than the ambient temp, but not below about 40°. Once it is able to reach these temps, it's good to go. Condensate should begin dripping out the bottom of the evaporator box after a couple of minutes of operation.

BOM:

• Compressor
• Fan clutch (if so equipped)
• Accumulator/dryer
• Rubber line
• Radiator cap
• Bottle of 100 PAG oil
• Pack of O-rings
• 3 cans of R-134a
• Solvent (probably will take about a pint)
• Gauge set
• Vacuum pump
• Clean white rags (bar towels are perfect)
• Thermometer

Who gives a crap what it costs? Do you want it to WORK, or what? It costs what it costs, and that's pretty much all there is to say about that; but just as a guide, I'd expect it to be in the $400ish range for all the parts and supplies. No need to have a "shop" do this, if you're the least bit mechanically inclined, and have a couple of big Crescent wrenches.

Fast355

iTrader: (2)

Sofakingdom makes some very good points and has great advice.

I will add a few other comments. While he has good luck with the orange/red orifice tubes, the GM systems respond very well to the Blue orifice tube from say a 1990 Ford Taurus with a 3.0 V6.

I personally adjust the cycling switch once I get the system properly charged and cycling correctly. Its been a few years since I have adjusted one, but from memory about 3/8 of a turn counter clockwise will drop the pressure it cycles off about 5 psi and make the vent temps about 3* cooler before it cycles off. A 1/2 turn drops the pressure about 8 psi and makes the system about 5* cooler at the vents. Most systems with a properly adjusted R12 cycling switch with R134a in them will blow about 48*F. 48*F does a poor job of dehumidification and cooling will suffer. I prefer to see vent temps in the 38-40*F range. My 03 Dakota gets down to 36*F before the compressor cycles off. The lines actually start to frost over before the compressor cycles. That was with the truck sitting at idle in 100*F ambient temperature and the a/c fan on high with a cooled down cab after my 45 minute drive home.

sofakingdom

iTrader: (1)

Never have tried the blue one... I'll have to check that out some one of these times.

Fast355

iTrader: (2)

It is a .067" orifice opposed to a .072" White "stock" GM unit. The smaller orifices that you are using might cool a little better around town than the .067" but the head pressure on the highway will be lower with the .067". With a fixed orifice it will always be a trade off of city vs highway cooling.

I will say one other thing, you are very correct on proper airflow affecting the cooling. The fan clutch was out on the 03 Dakota and I never realized it until I had a scan tool hooked to it and it was reading a coolant temp of 236*F where 210*F was more appropriate. When I changed the clutch the electric puller fan stopped turning on near as often and the a/c got cold as ice and it cooled well before.

budget builder

iTrader: (3)

thank you for posting this. This is a task that i will be tackling this winter. My wife wants me to try to keep the ac now that I'm finished witht the 350 swap

hwy quick rookie question would I have to change any of my fittings, hoses( I know that I might), evap, condenser, or drier? My car has all the stock ac stuff. I just dont know if teh 23year old is considered to be any good or there is a way to check. sorry for being rude not trying to jack your thread