come on, so i'm thinking it's low.

I bought a R-134 conversion kit from Advanced auto and it says to empty the old R-12, change fittings and put new stuff in. They said i don't have to change the comp, dryer or anything.

Do you guys think this will work? Has anybody done this conversion Kit?

 

When the shop converted mine from a similar kit, the mechanic also changed the dryer/accumulator. I think you really should when evacuating the gas from the system because it's considered contaminated once it's open.

It's cheap insurance from having your expansion valve get clogged up. That thing's a pain in the butt on ANY car, particularly a Vette. :yesnod:

 

that's what i was thinking too.

thanks

 

ice cold Ac for less than $100 bucks :)

 

Change the accumulator and the orifice. Put a Ford orifice tube in it ( it fits and has a smaller diameter, more pressure drop, more heat absorbed by flashing to vapor, more efficiency...and R134 needs the help)

You will have to adjust the compressor cycling/ low pressure cutoff switch to about 30 PSI cutoff pressure ( corresponds to about 30-32ºF ) or the evaporator will freeze up at higher engine speeds and no cold air will flow through it. The factory setting for R12 is about 25-28 PSI.

It is adjustable by using a small flat blade screwdriver to adjust the spring tension screw inside the switch...you get to it by removing the wire connector and inserting the screwdriver shaft in the hole between the contacts.

I did mine about two years ago and it pretty much keeps between 50º (when idle at 500 RPM in hot traffic) and 40º (cruising) air duct temperature.

 

I stuck with the r12........
replaced my compressor....everything pretty cool......
Put a chrome cover on it.....
and fan pullley....in aluminum....
along with a chrome shield.....so nothing spills onto the underside of the hood....
I'm happy, and it looks coooooooooooooooool.
tony
:flag :thumbs: :thumbs: :flag


[Modified by oldace84, 5:38 PM 6/27/2003]

 

Hey BBA Call me stupid but i just did the converstion and its working great but i was unsure of how to adjust the presure switch When you refer to the temps is ths the temps out of the vents? :cheers:

 

For adjusting low side pressure, you just conenct a low pressure gauge to the low side fitting, run the engine at a fast idle (about 1000 RPM) and see what the pressure gauge reads when the compressor clutch turns off....adjust the screw inside the switch until the compressor cycles off about 30 PSI. This will prevent freezing while cruising at steady speed.


...That is air temperature inside the main duct supplying the 4 center AC vents in the dash.



[Modified by BBA, 9:22 AM 6/28/2003]

 

With R134 you want lower, not higher pressure. At 30 psi, R134 boils at 35 degrees; R12 at 32 degrees. For the system to maintain peak efficiency, the cutoff pressure needs to be a couple pounds below the freezing pressure. This is why an R12 system is setup to cutout about 25 psi. R134 will boil at 32 degrees at a pressure of 27.5 psi so you want an R134 system to cutout at about 22 psi. To adjust, turn the screw in the center of the low pressure switch counterclockwise about 1/2 to a full turn. The adjustment should be made with engine at 1200 to 1500 psi, the main fan switch disconnected (so that air is being blown across the condensor) and if it's above 85 degrees, you may need to reduce the air flow across the evaporator by disconnecting the blower motor. Some switches lack the adjustment screw. If so, buy one that has it. If it won't adjust or cycle down with the blower motor disconnected, replace the switch. If it still won't cycle down, you may be overcharged. Check high side pressure. It should be no more than 2.2 to 2.5 times the air temp at the condensor (if you have electronic air with the outside air temp sender mounted on the radiator, use the readout on the dash - the air temp at the condensor can be as much as 20 degrees higher than the actual temperature due to engine heat and poor air flow across the condensor and this readout is usually more accurate). Finally, stick a digital thermometer in the center vent (a cheapo from the grocery store works fine). With R12 (from about 70 to 90 degrees), a Vette should blow 36 to 43 degees. R134, a couple of degees higher.

 

Had mine charged up this year with Freezone (don't remember the R factor). It is r12 compatible and you just add it to the system. Costs about $13 a can and requires a license to buy. It is ozone friendly. I was skeptical until I drove away and after about 2 miles my hands started to hurt from the cold. In SC, your ac is tested on a daily basis, this past year even in January for a day or two. Nothing had to be changed or emptied, and if you have a buddy with a license, you could get out for well under $50. Just a thought that has worked well for me.

 

Freezone is suppose to go into an "empty" system as are all of the socalled dropins. Don't know if Autozone is still having it's firesale on R12, but it was anywhere from $10 to $15 a can up until 6 mos. ago. Anyone can get a license at http://www.epatest.com or any of the other sites listed at http://www.epa.gov and then buy all the refigerent you need (about 4 cans for most Vettes).

 

You say that...but to keep mine from freezing, I had to raise the cutoff pressure.

Any argument you make after that will not be consistent with experience.


[Modified by BBA, 4:21 PM 6/28/2003]

 

I didn't make up the temp/pressure relationships, but not all systems are the same. I would suggest that 1, your gauges are faulty or need to be calibrated; or 2 - the charge is too low; or 3, the evaporator or suction side is restricted (and I believe the Ford O-tube does restrict it more than the OEM). Was there ice from the evaporator outlet to accumulator or from the accumulator to the compressor? On '88 through '91 models, make sure there isn't too much of a bend in the compressor hose from the accumulator to the compressor. GM redesigned it, but until it was available, dealer's were instructed to bend it down so it wouldn't hit the hood and in some, that created a restriction. Otherwise, the accumulator might be a problem. However, if you're happy with it and it doesn't cycle excessively or the high side isn't into the stratosphere, why worry?