AC Repair process-TJKJ2002, please check my logic!

jacob03kj · **Joined:** Mon Apr 18, 2011 10:47 pm **Posts:** 34

I wanted to check with y’all about the steps to recharging the KJ’s ac system. So my KJ was in a frontal collision in 2004, and sat in a shop’s yard for 7 years before I bought it and rebuilt it from essentially the ground up. One thing I never did was repair the AC system, and because the so-cal deserts are 120+ degrees, it would be nice if it were functioning. I have done everything from A to Z that is not extremely complex on vehicles (ie: transmission rebuild) and have tons of tools to work with. I have a new compressor, condenser, orifice line, and receiver/dryer. New o-rings/seals, and new Schrader valves for all the lines. I have access to a vacuum pump and manifold gauges, and have a full filter shop air compressor. I planned on saving the hoses from the condenser to the compressor, and from the compressor to the evaporator core. All the rest is new. I bought some pressure flush stuff to flush only the lines I am saving and the evap core, because all the rest is new and sealed.

From how I understand it, once everything is flushed extremely thoroughly, I will reconnect all the lines completely. From here I will add the specified amount of PAG 46 SP-10 weight oil into the low-pressure line (or should I pour it all into the compressor). Then add the specified amount of R134a via the low-pressure line. Is this correct? And what settings should the HVAC unit be on during this process? Anything I missed, and am I making any critical errors? Thanks a million!

tjkj2002 · **Posted:** Sun May 19, 2013 12:01 am

You need to drain the compressor of any oil and measure what comes out and replace with the correct PAG oil,add about 1 oz to the condensor,add 3oz to the reciever dryer,then add the rest to the low pressure line to make a total of 8oz.Then you want to pull a vacuum(must reach close to 30in,altitude dependant) on the system for 60mins at least before recharging to 1.63lbs of R134A through what ever port your machine is setup to feed the system.Some machines go through the high side and some the low side,while some can do either.Read the instructions with the machine for proper fill procedure.

jacob03kj · **Joined:** Mon Apr 18, 2011 10:47 pm **Posts:** 34

thanks so much, so assuming the compressor that is in my KJ now is empty, which if I remember correctly, I believe I drained it before I installed it. It just freewheels now like another idler pulley, and it was many-a-moon ago when I installed it. Can I just add around 8 ounces since the system will be "new", with a new, dry compressor. And do I literally just pour it in the compressor, condenser, and receiver/dryer. Also, are cans of freon measured in dry ounces, as in 16oz per pound rather than liquid ounces? So I would need a total of 26.10 ounces? Lastly, add oil before vacuuming? Thanks again, and sorry for the newb-ish questions. I have done tons of motor and axle work, just have never cracked open an AC system before and I want to make sure I'm not going to screw up my new parts!

tjkj2002 · **Posted:** Sun May 19, 2013 12:45 am

Use the correct machine with a highly accurate digital scale as you need to add the R134A by weight.Those 16oz cans actually hold maybe 10-12oz and will vary.

And yes you add the PAG oil directly into the parts,will have to turn the compressor by hand a little to get the correct amount in and not the free wheeling clutch pulley.

jacob03kj · **Joined:** Mon Apr 18, 2011 10:47 pm **Posts:** 34

Awesome, thanks so much for all of your assistance, it is greatly appreciated! I'll let you know how it goes when I have a day to dedicate to the KJ in the next week or so! Once again, thanks!

WolverineFW · **Posted:** Sun May 19, 2013 10:59 pm

Your new compressor should already have oil in it. I have never seen one come without oil in it.

If you are unsure or cannot figure it out, try emptying the oil out of the compressor and refilling with the same amount.

jacob03kj · **Joined:** Mon Apr 18, 2011 10:47 pm **Posts:** 34

interesting about the oil in the compressor. If there is oil in there, do I have to add any to the other parts of the system? Or will there be enough in the new compressor to fulfill the needed amount of oil in the whole system?

audiboy86 · **Posted:** Mon May 20, 2013 7:20 am

If you are unsure about the compressor empty it to be sure and yes everything must have oil added other wise you will end up with a dry systems in spots and a locked up compressor shortly afterwards.

Ted15 · **Posted:** Mon May 20, 2013 8:00 am

audiboy86 wrote:

If you are unsure about the compressor empty it to be sure and yes everything must have oil added other wise you will end up with a dry systems in spots and a locked up compressor shortly afterwards.

Believe it. I added all of the oil with the refrigerant when I replaced a compressor. The thing locked up after about 20 miles. Fortunately it was a junkyard part so I wasn't out much.

WolverineFW · **Posted:** Mon May 20, 2013 2:52 pm

audiboy86 wrote:

If you are unsure about the compressor empty it to be sure and yes everything must have oil added other wise you will end up with a dry systems in spots and a locked up compressor shortly afterwards.

Sorry but this is incorrect. Ideally all of the oil would remain in the compressor. The oil's only purpose is to lubricate the compressor. It just so happens that a small amount of the oil will travel with the refrigerant out into the system. They are designed to have sufficient refrigerant velocities to return the oil to the compresser.

Of course small amounts of oil will be out in the system at times. This is why automotive manufactures have listed amounts of oil to add to a system if you are replacing other parts and not the compressor. They want to ensure any oil that happens to be out in the system is replaced with the new part so the total oil charge remains the same.

This is also why TJKJ2002 stated to pour the oil out of the empty compressor and measure it. That way if any oil was out in the system during just a compressor replacement, you would only be adding back the correct amount of oil so it would not be overfilled, which can cause its own issues.

Sure compressors can lock up due to lack of lubrication, if they do not have enough oil in the compressor.

Large commercial refrigeration / Air conditioning systems will often employ oil separators off the compressor discharge to return the oil to the compressor before it gets out in the system.

adamkrz · **Posted:** Mon May 20, 2013 9:32 pm

WolverineFW wrote:

Your new compressor should already have oil in it. I have never seen one come without oil in it.

If you are unsure or cannot figure it out, try emptying the oil out of the compressor and refilling with the same amount.

The last few a bought had no oil, They were also tagged as having no oil, The best way as stated is to empty the old compressor and add what was removed.

I've seen condensers that were ruptured lose half a oil charge.

WolverineFW · **Posted:** Tue May 21, 2013 9:46 pm

adamkrz wrote:

WolverineFW wrote:

Your new compressor should already have oil in it. I have never seen one come without oil in it.

If you are unsure or cannot figure it out, try emptying the oil out of the compressor and refilling with the same amount.

The last few a bought had no oil, They were also tagged as having no oil, The best way as stated is to empty the old compressor and add what was removed.

I've seen condensers that were ruptured lose half a oil charge.

Absolutely.....high pressure discharge gas tends to blow oil out of the condenser.....makes it easy to find the leak. :mrgreen:

AC Repair process-TJKJ2002, please check my logic!

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