AC Recharge after engine swap

[1950StangJump$]

So, got it recharged .... I think.

I put a new dryer on. Then used the pump, put vacuum on it, which held for an hour. So, no leaks.

Then turned the pump back on and ran for an hour to remove moisture.

On to the Freon. The sticker said it holds 1.625 lbs (26 oz). So, I added 2ish oz of oil and expected to be able to fit in 24 oz of Freon.

Got one 12oz can in. But, the second stalled at about half a can, and it wouldn't take more no matter how I manipulated it. I wonder if the aftermarket condenser held less than stock.

When I gave up, the air coming out of the vent was mid-40s then ... after the car had been idling an hour in a 95+ degree garage. Sound right?

The compressor would go long periods without cycling off and on, which I think is how it is supposed to be.

 

[Juice]

Sounds about right. I think you got it.

One thing was not mentioned, AC should be on "Fresh air" (not max) and fan on max while adding refrigerant.

40F* temp is good.

 

[1950StangJump$]

Sounds about right. I think you got it.

One thing was not mentioned, AC should be on "Fresh air" (not max) and fan on max while adding refrigerant.

40F* temp is good.

Well, I had it on "max." Temps closer to 45-47 (Hot idle and 95ish temp garage) .... did the max part prevent me from filling up?

 

[Juice]

Well, I had it on "max." Temps closer to 45-47 (Hot idle and 95ish temp garage) .... did the max part prevent me from filling up?

Probably not. The main thing is, how does it feel driving? Cold enough?

 

[1950StangJump$]

Can't drive the car yet cause haven't go the IC pump. Only idling for now, and it "feels" cold

 

[RavenGT]

The compressor would go long periods without cycling off and on, which I think is how it is supposed to be.

No, undercharged. Add more refrigerant by charging with the engine on and A/C on. The compressor will pull in more refrigerant.

 

[1950StangJump$]

No, undercharged. Add more refrigerant by charging with the engine on and A/C on. The compressor will pull in more refrigerant.

Are you basing your assessment solely on the compressor on/off statement? Maybe I didn't write it correctly .... I charged with the engine and AC on.

At first when empty, the compressor didn't kick on. Then, with a little Freon, it kicked on and off frequently, which I always understood to be a characteristic of low Freon.

Then, when it wouldn't take in any more Freon (system full?), the compressor would stay mostly on ... cycling off and back on very seldom.

 

[RavenGT]

OK then. Sounds like you got it right.

 

[1950StangJump$]

So, started her up this morning in a 70 degree garage.

AC quickly cooled .... air coming out of the vents got down as low as 35, which I *think* is good for just an idle.

But, the compressor was cycling on and off a bunch. Would kick on for about 4 seconds, then off for 8 seconds. Was doing that like clockwork. Shut the engine down after about 10 mins and before it got to full operating temp.

Is this too much cycling and indicative of still being low on Freon? I never paid attention to it before the motor swap.

EDIT: Perhaps the cycling is a function of idling at low ambient temps?

Yesterday, when hot as shit and a very hot car, the compressor clutch was staying engaged for long periods

 

[Juice]

It can and will cycle faster in cooler temps. It is all about keeping the evaporator from freezing up.
You need to take a long-ish trip on a hot, full sun day. Then see if it can keep the car cool/comfortable. Go drive, its fine.

 

[1950StangJump$]

Great thing about this stuff .... forces you to learn a little.

Did some research, and learned the compressor cycles to keep from freezing up (common knowledge). But, that's exacerbated by cooler ambient temps, as well as using the RECIRC, as it's colder air that passes over the system. Also worse when the fan is on low, as it doesn't carry the near freezing temps away as fast.

Sure enough, garage at only 75 degrees, if I ran RECIRC and low fan, the clutch cycled on/off every 5-8 seconds as noted a couple posts above. But, turn on fresh air and max the fan? Then the compressor gradually increased ON time until it was on for long periods before cycling off briefly. When I went back to RECIRC and low fan setting, it went back to cycling frequently.

Did it a few times to make sure I saw what I was seeing. Happened every time.

I'm still not 100% sure my Freon is full, but I can't complain with 35-37 degree air, so I guess I'll leave well enough alone.

 

[Juice]

An AC system may not work best at the advertised charge level. It could work better possibly with a little under charge, or a little over charge.
Main point is, it's not like your engine oil level where low is bad. Low refrigerant will just make it not as cold as it should be. It will not hurt the system.