Got a 79 trans am and am replacing the a/c compressor that came with no oil. have a retrofit kit that have refrigerant and oil mix together. Is that all I need or do I need to put additional lubricant in the compressor?

You don't have to remove the oil.
You can simply charge the system with R134 as long as it has no R12 in it. In some cases the accumulator/drier and/or the orifice tube will need to be changed to improve the performance of the system.

Yes, depending! You would have to get an A/C retrofit kit(basically all it is is a couple "adapters" for the old "refill" HIGH, and LOW ports)
From R-12 to R-134A
(Unless all of this is already done, OR you find someone with R-12 and the right equiptment!)
After you get the retrofit kit, you'll need to COMPLETELY flush the system, get new PAG oil, and refrigerant, get a vacuum on your seems, introduce the PAG oil, reinstate vacuum, and add your refridgerant!


If you could find someone with R12, and the equiptment for R12, it MAY be cheaper. and R12 gives a colder A/C

1991 might be an R12 system. If so finding the refrigerant will be near impossible. Federal regulations took it off the market and now an 'ozone friendly" R134a refrigerant is used. You will need to retrofit your system to use this new refrigerant. wal Mart probably doesn't carry the "retrofit" kit. You need to make a trip to your local auto parts store for the kit.

R12.... In 1994 R134a was required, but some changed earlier. Yours may have been converted. If the service ports are threaded it still has R12. Hope this helps.

Hi!!
Unfortunately, the R-12 refrigerant that your compressor used was phased out on 1994. You will need to an Automotive A/C Shop to have the system evacuated, flushed, vacuumed, retrofitted and charged with R134a refrigerant. This job requires the use of specialized equipment and according to EPA regulations must be performed by a licensed HVAC Technician.
Once your system was retrofitted, if you ever need to re-charge refrigerant. All autoparts carry easy to use, instructions included, R134a refrigerant recharge kits.
Good Luck!! A HELPFUL - 4 THUMBS - rating for this solution would be greatly appreciated. Thank you for using FixYa.

I have upgraded or retrofitted older cars with r134a before with the ester oil and never had any problems with the refrigerant working with the old oil, as long as you put a few ounces of the new oil in.

The kit for r134a conversion from R-12 has everything you need to upgrade without removing all of the old oil.

Of course, in the early days of r134a conversion in the early 1990s there were people who recommended that you take the whole system apart, compressor, piping, receiver drier, etc. and replace the receiver drier and dump out the old oil.

In my opinion, this is a very expensive proposition, and good to excellent air conditioning can be had by following the R134a conversion kit instructions and installing 2 or 3 cans of refrigerant into your system.

This can be done by yourself.

Watch, if you're in California, you have to return empty cans of R134a to the store because they say that it is harmful to the environment and they want to keep track of it.

Good luck staying cool with R134a.

need to have the a/c system evacuated and flushed out with the appropriate cleaner.Replace the orifice tube and drier, and purchase a retrofit kit at any parts house. Recharge system with appropriate amount of oil charge and freon. It will take less R134a than it did R12.

Jeep GrandCherokee SUVs manufactured in or before 1995 use R12 refrigerant. You must retrofit these SUVs to accept R134 refrigerant using a retrofit kit available at your local auto parts store before you can recharge the system. In some areas, a license is required to retrofit an air conditioning system. If this is the case in your area, take your Jeep to a professional to retrofit the system.

Instructions:

1. Step 1 Take your SUV to a mechanic to recover the R12 refrigerant out of the air conditioning system. A license and special equipment are needed to do this. Because R12 refrigerant is expensive, many mechanics will do the job for free.
   
2. Step 2 Locate the Low Pressure Side connector port. You will find it on the driver's side of the engine. Remove the blue or yellow cap marked L. You only need to retrofit the system if you see a screw-type connector valve. If you see a quick connect valve, the system already is R134 compatible. Wipe the connector valve off with a clean towel. This ensures that the retrofit connector properly adheres to the valve.
   
3. Step 3 Place the long retrofit connector from the automotive retrofit kit onto the Low Pressure Side valve. The retrofit connector has a special adhesive on the threads that will help it adhere to the valve. Screw the connector onto the valve. Tighten the retrofit connector using an adjustable wrench. Place the cap provided in the retrofit kit onto the retrofit connector. This keeps dust out of the system.
   
4. Step 4 Follow the air conditioning lines away from the compressor until you see the High Pressure Side port valve. This is located near the Low Pressure Side service port. Remove the red cap and wipe the port off with a towel.
   
5. Step 5 Put the shorter adapter onto the port. Twist it using an adjustable wrench until it is securely fastened to the port. Place the red cap from the retrofit kit onto the adaptor.
   
6. Step 6 Fill out the Retrofit Identification sticker provided in the retrofit kit using a permanent marker. Remove the protective backing and place it on the interior side of the hood. This lets future owners and service professionals know that the system has been retrofitted.
   
7. Step 7 Recharge the air conditioning system. See the related eHow titled "How to Recharge Air Conditioning with Freon in a Jeep Grand Cherokee."
   

WARINING:
Never try to evacuate the system yourself. A license and special equipment is needed to evacuate the system. Attempting to do this yourself will release refrigerant into the air, which is a federal crime.

Good luck (rated this help).

First, the old R-12 must be completely evacuated fromt the system. R-12 and R-134A do not mix and won't function together. Once you are sure there's no R-12 left in the system, you need to install an R-134A fill valve on the low side AC line. This is where your refill hose will connect to add R-134A. Once the valve is in place you're ready to fill the system. The compressor requires a minimum of 20psi to engage and should not be filled to more than 45psi.

RECHARGING AC SYSTEM

1.Turn the truck on and turn AC on HIGH
2.Locate the low side AC line (will have a valve and cap similar to the cap on a tire)
3.Insert the oil or R-134A can to the hose (Do not turn the screw to puncture the can yet)
4.Insert the other end of the refill hose to the low side valve
5.Puncture the R-134A can with the screw on the refill hose
6.You should feel the system suction the refrigerant out of the can
7.Check for frost on the AC lines and the air blowing inside the truck
8.If frost develops and the air is cold, you've successfully recharged the system and disconnect the refill hose. DO NOT ADD MORE REFRIGERANT...overcharging the system will damage your compressor and will be less effective
Hopefully this answers your question and you're able to get your AC working again. Best of luck.

on this old of a car it should be leak tested to find any leaks,a retrofit is possible but doing it right is lots of labor and parts . The right way is to replace the compressor and reciever /dryer to 134a compatable units, and replace all seals to 134a compatible ones and flush the whole system with cleaner and pull a vacuum on it twice to remove all air put the right amount of the correct oil in and then recharge. That all most likely costs more than this vehicle is worth. The cheap way is to flush out the old oil and refill with the right stuuf for 134a and put adapter fittings on it and charge it up. If it works for one season sweet! If not your not out much $$