Cessna 414 AC system

Avi Lavon

Filing Flight Plan
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Avi
Hi ,
I need to charge my AC system. two questions:
1. how many Freon pounds are in the system ?
2. where do i buy R-12 Freon ?
Thank you.
Avi
 
anyone else in the forum with Cessna 414 ?
 
If you’re in the states, you gotta be licensed to buy R-12 by the EPA. The purchasing tech can be an A&P who has this cert or an automotive AC tech that your A&P can work with. Don’t buy the so-called “R-12 compatible” stuff, because it isn’t.
 
If you’re in the states, you gotta be licensed to buy R-12 by the EPA. The purchasing tech can be an A&P who has this cert or an automotive AC tech that your A&P can work with. Don’t buy the so-called “R-12 compatible” stuff, because it isn’t.
 

Thank you . Any idea how many pounds the system required ? I’m based @ KCDW
 
Those "drop in" replacements don't work well, and they contaminate your system, requiring a purge and evacuation before returning to the proper refrigerant. Flyer 770's post is on the money.

Conversion to R-134A can result in unacceptably poor performance.

One pound cans of R-12 costs around $40-$60 on eBay, so buying two or three isn't the end of the world. The way your question is framed, it sounds like you may be planning to do the work yourself, which isn't particularly difficult.

Right now there is a Cessna air conditioning manual for Models 172 through 421 for sale on eBay. It might answer some of your questions about refrigerant capacity, etc.

Someone will be along shortly to contradict me and tell you how dangerous this is.
 
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Doing it so it works (assuming you can find R-12) isn't too hard. Doing it in accordance with the current EPA guidance takes training and some expensive tools. All R-12 for a number of years now is reclaimed. You are supposed to vacuum down the system reclaiming the R-12 that's in it for filtering and re-sale. Then effect repairs (if it's low on refrigerant it's going somewhere. Find it and fix it. It may be a very slow leak.) then vacuum down and leak test, then refill with reclaimed R-12.

R-134a is not as efficient as R-12 even though it was a "drop in" replacement. It didn't work that well in stock R-12 systems. Newer cars have larger systems designed to work with R-134. All of this may be out of date or moot for aircraft, except R-12 is reclaimed and very pricey. And you need to be licensed to work with it.

John
 
This is dangerous, whatever you do, don't attempt it yourself.

The modern R-134a stuff is better for the environment, but it’s more toxic to the tech. Cancer is fairly common with inappropriate servicing, especially testicular cancer. If you have a decent leak and it splashes in your eyes, it can freeze your eyeball. It also displaces oxygen in enclosed spaces and can suffocate you.

Suggest just paying a proper tech to do it.
 
Back to original question. A full charge is 2.5 pounds of R-12.
 
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The modern R-134a stuff is better for the environment, but it’s more toxic to the tech. Cancer is fairly common with inappropriate servicing, especially testicular cancer. If you have a decent leak and it splashes in your eyes, it can freeze your eyeball. It also displaces oxygen in enclosed spaces and can suffocate you.

Suggest just paying a proper tech to do it.

.

Eye protection is a must. I've trained myself to wear safety glasses when doing any sort of auto work, and most yard work too. It's a pain in the summertime when it's 98 degrees, but like your high school shop teacher said, you only have two and they don't make replacements.
 
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Eye protection is a must. I've trained myself to wear safety glasses when doing any sort of auto work, and most yard work too. It's a pain in the summertime when it's 98 degrees, but like your high school shop teacher said, you only have two and they don't make replacements.

I finally found a good type that I like and now but them in six packs. Hell, one of my A&P instructors said to a student that wasn't wearing glasses that she had pretty eyes and it would be most unfortunate if something happened to them. Hopefully everyone in earshot took that advice and got into the safety glasses habit. Though I already was fixing cars and semis. I like seeing way too much.

Yes, the stuff is safe when properly handled. I'm still going to try to put it foremost in mind the worst case about taking appropriate safety precautions so it does become as safe as one can make it.
 
BTW Cessna has a very detailed (339 page) Air Conditioning System Service/Parts Manual. It covers the 414 as well as other models with factory air. This stuff is NOT covered in the 414 Maintenance Manual. You’d best have this in hand if you’re going to DIY.
 
Back to original question. A full charge is 2.5 pounds of R-12.

Can't answer that question but looking at "full charge" is not the way to look at it either. Go by pressure on the high and low side at a given temp.

Edit, should be directed to OP
 
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BTW Cessna has a very detailed (339 page) Air Conditioning System Service/Parts Manual. It covers the 414 as well as other models with factory air. This stuff is NOT covered in the 414 Maintenance Manual. You’d best have this in hand if you’re going to DIY.

.

That's the one I spotted on eBay. If I was an A&P or had a Cessna with A/C I would buy it in a second. Forty bucks is cheap for a manual that covers all the details of Cessna A/C systems, and the format is a searchable CD.

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https://www.ebay.com/itm/CESSNA-AIRCRAFT-AIR-CONDITIONING-SERVICE-MANUAL-/282047320272
 
Can't answer that question but looking at "full charge" is not the way to look at it either. Go by pressure on the high and low side at a given temp.
OP asked “how many Freon pounds are in the system?” So I answered it right out of the manual.
If OP cares, pressure on LP side should be 25 to 65 psi and on the HP side 100 to 275 psi. The manual has a chart for temperature adjustment.
Better?
 
I should have phrased that differently so it was directed to the OP not you. Adding Freon willy nilly is not really what you want to do, it's a good way to ruin something expensive, especially for an aircraft. The OP didn't seem 100% sure on this procedure.
Better?
 
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I've got a P210 converted to R134, it takes a little longer to get cold, doesn't get as cold as R12, however it still gets cool enough in the cabin on those hot summer southern California days.
It usually takes about 2.5 cans and it's topped off. Check to see if you have a hi and low pressure switch in the system this will help also when filling not to overfill and safeguards the system. Lance F is correct the pressures should be 25-65 on the low side, 40-45 is ideal, 100-275 on the high side ideally about 170-180, I have both high and low switches installed and so far so good no problems fill it till I don't see the freon flow in the gauge manifold window. Pressures reach 45 on the low side and around 190 on the high side if I remember correctly from the last time I charged the AC. If you do convert to R134, you'll have to change the fittings to 134 fittings (R12 fittings are becoming more and more rare on manifold gauges), make sure to vacuum out the system and purge any R12 that may still remain in the system, add oil, check for leaks and fill in R134.
 
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