A/C refrigerant questions

[dan468]

I would like to convert my A/C to the new freon...what needs to be changed?
It's a 1990 1/2 350

[Luv68's]

I think a 1990 is already the new refrigerant. Double check to see but it should R-134a already.

[70 Suburban]

90 could be ether. but im sure there are lots of threads here that tell you if not its all over the net.. google is your friend

[ProStreet68SB]

'90 pickemups are still going to be r-12

[dan468]

Originally Posted by ProStreet68SB

'90 pickemups are still going to be r-12

what do i need to change in the truck to make it r134?

[72C10chevy4x4]

you've got the R-12. Take it to a shop and have them pull a vacuum and evacuate all the contents of the system, then they will refill w/ r134. I don't think it's as simple as buying cans of freon from a store, the old stuff will still be in the system.

seems I saw a conversion kit in a JCWhitney catalog-feel free to research on your own. I've never been able to find a vacuum pump to rent...

[72BLUZ]

You Need To Install Charge Ports For The 134 Connections. They Are Direct Fit To The R12 System. And I Recommend Installing New Pressure Switches For 134 Systems. And Then Contact The Local A/c Repair Shop For The Proper Amount To Charge To Your System. It Will Be Less Than The R12 System. I Just Cant Remember The Amount. Seems Like Its About 75 Percent Of What The R12 System Held. Or You Can Pull A 30 Min Vacuum And Start Charging Your System With 134 And Monitor The Gauges And Put A Thermometer In The Center Dash And Watch The Temp. Get The Low Side To 35 To 40 And Check The Temp. If It Reads About 40 Degrees. Then Stop And It Should Be Close

[get me on the road]

If you do take it to a shop, or do it yourself, make sure that some lubercant is added which also has dye in it, to help find any future leaks.

[airdale94]

I would just throw some Freeze 12 in it. That's what I did with my 93.

[dan468]

Wow thanks guys. Sounds like other than the connectors I don't have to change O-rings or anything. My dad's shop has the vaccum stuff so this should be cake.

[airdale94]

Originally Posted by dan468

Wow thanks guys. Sounds like other than the connectors I don't have to change O-rings or anything. My dad's shop has the vaccum stuff so this should be cake.

If your dad's got a shop and you're in Sun City he's probably got a set of R12 gauges. Just get side can tap and throw the Freeze 12 in. You don't even have to evacuate the R12 or change the fittings.
Freeze 12 is compatible with R12. You can even buy the oil charge cans of Freeze 12 and dye charge to check for leaks.

[bwood]

If you do convert to r134a, you will need to pull the compressor and drain the oil, r12 oil is not readily compatible with r134a. It might work for a while, but serious compressor damage could occur. I would also recommend changing the dryer/accumulator and oriface. These are places where contaminates and oil gather. The dryer and oriface should only run about $40. Also flush all the lines with a/c line flush while everything is unhooked. Make sure all of the line flush is evaporated and install everything except the compressor and accumulator/dryer. You will need to put oil back in the compressor. Ask your parts store for r134a oil for GM compressors and have them tell you how much it takes. Put half in the compressor (in the suction side, bigger port) and the other half into the inlet on the accululato/dryer. Install the compressor, accumulator/dryer and lines. Turn the compressor by hand in the proper direction to circulate the oil into the compressor. Pull a vacuum for at least 30 min. and make sure it holds for as long. If it does not, I use a little nitrogen (about 30 psi) and soap all of the connections. Let the pressure off and pull the vacuum again. I usually let it go for about and hour, then make sure it holds again. If it does, use the vacuum on the system to pull in one can of R134 into the system. You will need to add more refrigerant, but the compressor needs to be running. Start the truck and put the a/c on high/max, if the compressor does not spin, with another can of r134 hooked up and ready to go, pull the wire harnes off the low pressure switch on the accumulator/dryer and put a paper clip across the harness terminals. This will make the compressor run. Do this until you have met your aproproiate refrigerant charge. You will need to get some guages and a chart that shows proper refrigerant pressures according to the outside temp. I usually go by the high side of the compressor. NOW this is a lot of details, but I'm sure I have left something out. If you are not fairly confident in doing this, take it to a professional. That way if something goes wrong, somebodty else will be responsible and will have to make the repairs.