ac refill
 

Hey all quick question for clarity.

I need to refill my ac before summer, it's empty after a engine swap. Last summer I refilled it myself with the vacuum and all that gear, having replaced the evap core.

My question now, is it safe to simply repeat and refill the system or shoukd I take it in somewhere to refill?
I ask because ive read the machines read oil/Freon levels and can adjust accordingly.

If it's not a big did shoukd I refill no with no oil additive Freon?


Thanks

Did you add oil when you changed the evaporator? Can you estimate how much oil was lost when the system emptied? Really the only way to know for certain how much oil is in there is to get the old oil out and add back in the correct amount, but a reasonably close estimate is OK. Probably would not hurt to add an ounce or two to cover losses from when the system was opened up.

If the AC system has been open to atmosphere for a while the drier should be replaced, and oil added to replace what's in the old drier. When replacing major parts you can drain and measure the old oil to determine how much to add.

There are also rules of thumb you can follow to add the approximate amount of oil required after a leak or component replacement, such as the chart on this page: https://www.buyautoparts.com/howto/a...-oil-level.htm

Dont mean to hijack but the dryer is a replaceable item?

Yes, in fact it is pretty much a disposable item. Strictly speaking it is supposed to be replaced any time the system is opened up or otherwise exposed to atmosphere. (Though if the exposure is brief you can generally get away with leaving it in.)

The dryer contains a desiccant with a limited capacity for absorbing atmospheric moisture, and it also acts as a filter to trap small particles. The desiccant can become saturated if the dryer is exposed to atmosphere for more than a few minutes. (Aside from reducing performance, moisture in the AC system can combine with R134a to produce acids that eat small holes in metal parts such as the evaporator.) The dryer should be the last part to be installed, just before pulling vacuum.

i thought it was replaced with the condenser as it was built into it?

No, on the XJ the drier (AKA accumulator) is near the back of the engine compartment on the passenger side (at least it is on my '99). On different vehicles though it might be located just about anywhere the designers find room for it. (On my daily driver the drier is inside one of the front fenders.)

A dryer and an accumulator are two different things.

Not necessarily. At least on the vehicles I've worked on the drier, accumulator, and filter are all integrated into the same part.

Ok so I got a maybe on wether I can safely refill the system. I know you can add too much Freon, can too much oil be an issue. It's like 2 oz for each part replaced, but if you did 3 or 4 will it be a problem?

The accumulator stayed hookjed up this go around, I had it disconnected from the condenser and stuff towels in the lines to keep crap out. Does the accumulator still need to be replaced?

Too much oil can cut down the effectiveness of the AC system. However too little can destroy the compressor, so it is probably better to err on the side of caution. I'd say 3 or 4 ounces per part is way too much, and oil capacity of each part varies. Bear in mind the total oil that is supposed to be in the system is a little over 8 ounces per the 1999 factory service manual, so if you start adding oil blindly you will wind up with way too much.

The manual recommends adding 1 ounce of oil after a leak has been repaired, and assigns the following amount of oil to various components:

Total AC system: 8.1 oz.

Accumulator: 4 oz.
Condenser: 1 oz.
Evaporator: 2 oz.
Compressor: Drain and measure

The general rule of thumb I've seen for hose replacement is 1/2 ounce per hose.

Whether you need to replace the accumulator/drier depends on how long it was exposed to atmosphere. Anything more than perhaps 5 minutes is suspect. However I have seen people get away with having them open for a longer period of time. If it's been days or weeks though I would certainly replace it.

So even if I didn't disconnect anything from the accumulator you're saying I should replace it and add some oil.
I replaced it last year I think I put 2 oz in it. But the heat is hear and i need to get a/c going.


Does a shop tool not sense how much oil and Freon are in the system or does it just measure freon?

If the AC system was open to atmosphere for a while the drier is toast even if it wasn't disconnected. It still absorbed atmospheric moisture during the period of time the system was open.

The shop can check system pressures but can't tell how much is actually in there unless they recover and measure it. As far as I know they don't have a way to measure oil.

There is a product that purports to let you know how much oil is present (probably by concentration, it's obviously not checking volume) but I haven't tried it:

https://www.es-refrigerants.com/prod...0a/details.asp

if the system was open is there anything to "flush"?


i think ill refill today and get an accumulator/drier

Well since the compressor didn't seize up you shouldn't have any debris in there. The only other reason I can think of offhand would be to remove old, moisture-laden oil to replace with the correct amount of fresh oil. The PAG oil used with R134a absorbs moisture very readily and that moisture is not removed by pulling vacuum. However I'd say that most people don't bother doing this unless doing a major overhaul. (If you get the idea that fighting moisture is a big deal in these AC systems you'd be right.)