[quote=graven57;6183857] OK, that was probably your main leaker. The thing is, the seals in the rest of the fittings are the same age. They should all be replaced for the sake of longevity. Many parts stores sell an o-ring kit that will do all of the spring lock connections for about $6. Since you are removing the accumulator and the orifice, resealing is very cheap insurance

Do you have access to an air compressor? If so, you'll need to flush the system with solvent. If not, you can make do. Flushing will get all of the old oil out of the system and get you back to a baseline. There's no way to tell how much will still be in the evaporator and condenser.

Here's a shopping list with approximate prices:
-Accumulator $35 (~$65 with the suction line)
-Orifice tube- red $2
-Oring kit $6
-Compressor manifold O-rings $1.50 (Your compressor might have 2 threaded fittings. They should be in the kit)
-2 cans of virgin R134a $24 (No additives or sealers)
-1 can of R134a with UV dye $9
-Can tap (without a hose)
-2 8oz bottles of Ester 100 oil $12

For flushing you'll need 1-2qts of solvent (lacquer thinner, denatured alcohol or similar) and some miscellaneous hose to connect to the evaporator and condenser fittings. Heater hose and clamps works well.

First, you need to have the remaining refrigerant in the system recovered. You'll start with an empty system. This will sound like a lot of steps, but it really isn't. You should be able to do it in about 4-5 hours if you haven't done it before. Work slow and be methodical. If you have any questions, ask before you start. Here goes:

-Disconnect the lines from the compressor and remove the compressor. Set it aside.
-Remove the compressor to condenser line.
-Remove the accumulator to compressor line (it may be crimped to the accumulator. If so, it is replaced with the accumulator).
-Remove the accumulator.
-Remove the line from the condenser to evaporator.
- Pull the orifice tube from the evaporator inlet tube (smaller tube). Make note of how it's installed. Needle nose pliers usually work well for this.

You are now ready to flush. You'll need some hose to direct the discharge into a bucket or other container.
-Pour about 6-8 ounces of solvent into the evaporator outlet tube (upper tube) Lightly blow air into the lower tube to agitate. Then blast air through the upper tube to clear the solvent. Blow air both ways until there is no more liquid in the evaporator.
-Repeat that process for the condenser. Make sure that they are completely dry inside.
- Pour solvent into any old hoses that you are reusing and blow them dry. Do not pour solvent into the accumulator or compressor!
-You will "flush" the compressor with the oil that you are going to use in the system. Hold the comp with the ports facing down and spin the clutch. Drain out as much oil as you can.
-Add a few ounces of oil to the inlet port while spinning the compressor.
-Drain the compressor and repeat.
-Drain the compressor as well as you can.
-Remount the compressor.

You need about 10 ounces of oil in the system. If the original tag is on the truck, the exact amount will be shown there.
-Divide the oil between the condenser, evaporator and accumulator. Just pour it into each one.
-If you didn't flush the system, only add 6 ounces and cross your fingers. Too much oil can be as bad as not enough

-Lubricate the new orifice tube and install it into the evaporator inlet.
-Reinstall the hoses, replacing the orings and lubricating the connections as you go. Just match the old ones to the new ones. Clean both parts of each connection as you go.
-Swap the cycling switch from the old accumulator. Make sure there is an oring on the fitting of the new accumulator. A new switch is about $6 BTW, cheap insurance).
-Look into the connector on the cycling switch. Turn the screw between the terminals counterclockwise 1 turn.

Now to evacuate and leak check.
-Connect your manifold set and vacuum pump to the charging ports.
-Fully open both handwheels on the gauge set and turn on the pump.
- Run the vacuum pump for about 10-15 minutes. The low side gauge should read 28"-30" of vacuum. If not, you have a leak.
-Close both handwheels and turn off the pump.
-Watch the low side gauge for 10-15 minutes. It should not rise at all. If it does, there is a leak.
-Turn on the pump and open both handwheels. Let it run for about an hour.
-Close the handwheels and turn off the pump. (You will not open the Red High side handwheel again)
-Disconnect the hose from the vacuum pump.

Now to charge the system. You want to start with about 80% of the original R12 charge amount. IIRC, it was originally 36 oz, so you will start with 30 oz.:
-Put the can tap onto the can of refrigerant with the UV dye. Shake it up.
-Connect the tap to the center hose of the gauge set and pierce the can.
-Fully open the low side hand wheel and hold the refrigerant can upside down and let the system take as much as it can.
-Start the engine, turn the AC on, high blower, doors open, block the idle at about 1000-1500 rpm if you can.
-Jumper out the cycling switch connector.
-The refrigerant can is empty when the entire can is at ambient temp.
- Close the low side wheel, remove the hose from the can tap and install it on the next can.
- Reconnect the hose, pierce the can and open the low side handwheel. Don't invert the can.
-Watch the High Side pressure. If it goes over ~250 while charging----STOP!
-If the system is slow to take the refrigerant, hold the can in a bucket of warm water to help raise the pressure. When the whole can is warm, it's empty.
-Remove the jumper from the cycling switch connector and connect the switch.
-Repeat for the third can, but close the handwheel when it is about half empty. This will be about 30 oz of refrigerant in the system. It should be cooling pretty good now.
-Feel the evaporator tubes right at the housing. They should be about the same temp and the suction line should be cool back to the compressor.

For pressures, you want to see around 1.5 times the ambient temp on the high side and 26-28psi on the low side at 1500 rpm, high blower, doors open.
If the high side is too high, try misting water on the condenser with a garden hose. If it drops like a rock either the condenser/radiator needs cleaned externally or the fan clutch is dead.
If the low side goes below 26psi, turn the screw in the switch clockwise 1/4 turn at a time. If it doesn't get that low, we'll deal with that later.
Once you get this far, post the ambient temp and both pressures. You can tweak the system from there.

Good luck!

 

Subscribing

 

...I'm subscribing too, in the hopes that this thread will revive, as it seems to have died.
Too bad, Isrx101 has posted what appears to be a top notch tutorial!
I have a 96 F150. Past 2 summers now (wow time flies) I've been living without air - tried adding refrigerant, and never could get the compressor clutch to kick in. I also purchased a hose and manifold set for when the time came for me to get into repairing.
My clutch kicks in when I jumper it (found that out today).
That's about all I know so far, until I found this most excellent write-up!
Thanks Isrx101!
Would really like to know how graven57 came out on his project!

 

I just bought a manifold gauge/vacuum pump set. I am using some Redtek r12a for older r12 systems. Are the instructions listed here mostly the same aside from the oil and refrigerant type? I jumped my compressor and it comes on so I just need to find the leak. I have a can of UV dye I'm going to put into it tonight and then hopefully I can find the leak and refill the system.

 

Alright! Today I went to pull a part. I got this plug off an ac compressor and soldered in a bit of wire and an alligator clip to make a pretty handy jumper. I turned the truck on, hooked up the refrigerant, hooked up the jumper with the ac on full blast and the compressor kicked right on. Once I had the system up to pressure I was able to disconnect the jumper and reconnect my ac plug and the compressor now works as normal. I used a temperature gauge and the AC went from 98 to 75! It feels nice and cool. I was in the truck with the windows up while it was about 95 today and I was not hot at all.

2 questions:

1 I. have the r12 system which I am charging with Redtek 12a (which is safe for r12 vehicles). What should the pressure be on the low side service port? I want it colder but 75 will do so I don't want to over do it.

2. I used an oil analyzer and it came out black. I guess I need to run a vacuum and dry out the system with alcohol and add new oil?