AC Recharge after engine swap

1950StangJump$

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I haven't had to put Freon in a car since the old days with R12. I know the internet is riddled with "how to's" on this, but there is a wide disparity on whether oil is needed, whether it must be done professionally, how much, rent a kit, etc. I see cheap kits at auto parts stores, and then I see kits to buy or rent that have vacuum pumps. Not sure what to make of it.

For background, my 2008 GT blew cold before the engine swap. Someone (I'm not saying who) evacuated it to atmosphere via the low side port before I did the motor change. I ended up swapping over the compressor and lines, but put a new condenser in since the old one was beat to hell.

Should I be able to use something like this, or perhaps something similar with oil already in it?

https://acprocold.com/product/acp210ad-6-a-c-pro-extreme-conditions-r-134a-recharge-kit/
 

RavenGT

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The quantity of PAG oil required depends on how much you lost, which will likely be less than seven ounces. That is roughly the amount added when replacing a compressor. Then a vacuum must be pulled on the system. Monitor the gauges for about 5-10 minutes to be sure the vacuum holds. If the needle starts creeping upwards, you have a leak. If leak-free, recharge the system with the specified amount of R134a. You will of course need a vacuum pump and a manifold gauge set.
 

Juice

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You need to put 30 minutes of vacuum on the system before you charge it.Autozone has A/C evac pumps for rent. (free, get your money back when you return it) If the system was slow purged, you may not even need any oil added. You should have an AC gauge set to view pressures, but if it was fine before, it should be fine now. Gauges connect the vacuum pump to the system. Don't know if Autozone rents those. Something like this: https://www.amazon.com/Manifold-Dia...jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==
That set includes the tap for the refrigerant cans btw.

Did you cap the open lines while the car was apart?

If no, how long was the A/C system open to the atmosphere? (Dryer maybe saturated if system was open for some time)
 

1950StangJump$

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I didn't cap .... didn't know I had to. Open to atmosphere for a about two months
 

Juice

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I didn't cap .... didn't know I had to. Open to atmosphere for a about two months
Leave it on vacuum for 1 hr or more. I have no idea how long it takes to saturate a receiver dryer. Anything more than a few hours, I cap the lines.
 

RED09GT

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Good news is a Motorcraft Receiver/Dryer is like $75 on Rockauto.
If you live in a humid climate, I'd bite the bullet and replace it if it wasn't capped off.
 

1950StangJump$

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Does it fix everything to pay a professional to flush and fill the system as is, or will I need a dryer regardless?

EDIT: To clarify, the only places left unhooked were the AC lines near the condenser and the compressor - only what was necessary to swap the motor. These lines stayed in place, with the dryer, during the swap.
 

Racer47

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If it were me, I'd just borrow the vac pump, let it run a while, 30 mins to maybe an hour. Then i'd just buy the recharge cans that come with a gauge. They are about $30 each, 2 might be enough, 3 maybe. I don't know what the system holds from empty. Sure you could spend more and do more but its probably not needed.

I just topped off my 06 with this. It worked well and took less than one can.
https://www.walmart.com/ip/A-C-Pro-...MI1ouhxbS76wIVjsDACh3x5gwvEAQYASABEgJTOPD_BwE
 

1950StangJump$

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To be clear, the vacuum pump is solely to ensure there are no leaks, or is there another purpose?
 

Racer47

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it sucks out the water and air. But as a side benefit it does check for leaks.
 

Juice

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You need something to connect the vacuum pump to the car. The rented unit from Autozone does not come with any hoses.
 

1950StangJump$

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Based on everything I read here, I think I am leaning towards just paying someone to flush and fill the right way.

My hesitation is not about the $, as much as having someone else touch the car. I'll have to find someone who allows me to .... hover.
 

Racer47

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If AZ rents the pump, they probably also have the gauge kit which should have a hose for the vac pump. You are not the first one to do this. They should know what you need.

Also the recharge kit comes with a detachable hose with the correct connection to the low pressure side of the a/c system at one end. So the other end may also connect to the vac pump.

Overall, its really not hard or complicated. If you pay and watch, you'll leave wondering why you paid them $400 for that simple of a job.
 

Steve Waters

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It is of ultimate importance to vacuum the system and to replace the drier. Any moisture in the system can cause a blockage and stop the a/c from working. You will also lose some oil by replacing the drier and condenser. How much I don't know. If you still have the parts laying around you might be able to see if any oil will come out and measure it.
I would look at a few YouTube videos done by professionals just to get a better understanding of what needs to be done.

Hope this helps.

See ya.
 

1950StangJump$

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So, just to make sure we are on the same page, the drier was never removed. It and the lines were left in the car undisturbed

The system was evacuated through the low port, the original compressor was transferred to the new engine. The condenser was changed.

The lines were left open at the compressor and at the condenser.

Does that change anything here. Having to replace the dryer is new info
 

Steve Waters

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Moisture will get in the system even though the smallest of holes. The fact that your system was open for months means you definitely have moisture in the system. The drier is a moisture magnet so it either needs to be replaced or have a long vacuum session drawn on it, the longer the better. It's not rocket science but it's not Betty Crocker either. Whoops, there I go showing my age.

See ya
 

MrBhp

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I wouldn't use that recharge kit you linked. It has sealant. You never want sealant in your ac system. It's only going to seal what shouldn't be sealed, as in internal passages. It seldom ever seals a leak. If you do it yourself, you cannot bypass using the vacuum pump. You have to boil all the water out of the system. I would also replace the accumulator on any system that is opened. They are cheap. I won't warranty ac work without it.
 

07 Boss

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^ agreed. Get straight r134 with no sealants. If it says 'stops leaks' don't get it.
 

Macman45

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Just hopping in here since I have the same situation, new condenser going in. Whats a fair price to pay to take the car somewhere and have them vacuum the lines and dump in new freon and maybe oil if it needs it?
 

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