Questions for A/C Gurus

[kid]

Couple more A/C questions.

1) Way back when I first charged an A/C, (ancient late 1980's as I recall. We were still buying the good stuff, R-12, for .69 cents a can at the local department store), the procedure said that after you open the can of freon to the system to run the engine at 2,000 RPM for a couple of minutes. I've never seen this said since. Is there a point to this? Is it old school for old compressors??

We don't run them during the initial charge anymore as there is no oil in a rebuilt system to lubricate the pump. It leaked out with the Freon.

2) Also, the procedures back then said to empty the first can in the upside down position for the liquid freon then the rest in the upside position for the gas. This also isn't mentioned anymore although I've been doing it for many years with pretty good success. Also my Cherokee will not take any freon unless the can is upside down. Always been like this in the 6 years I've owned it. It used to leak a can or or a year and that's how I've done it every time and AC would work great until it leaked off. Last couple of years it's gotten worse so I just now finished putting a "new" compressor in, (the old one was leaking at a seam, I used the dye to find the leak), and this time I had the manifold and gauges to do it correctly, but it was the same thing, it would not take freon unless I held the can upside down. System is charged and working great now, but what gives???

When the can is upside down you get the liquid first. If the system is empty and under vacuum the liquid flashes off the vapor instantly. Once the system has a little charge the liquid will stay that way and a slug of liquid hitting the compressor will break the pump. (If the pump is running) So on partial refills or topoffs use the can right side up. I have done enough that I learned to tip the can and let liquid in but I listen for the sound of the liquid converting to gas and if I don't hear it I stop tipping in the liquid.

Don't run the compressor until the system is half full.

When I build the system in Yellow Brute I am going to make it like a modern system with R-134, Sight Glass, Filter and low pressure cutout and Wide open throttle cutout.

[kid]

The Blue cap is your low side service port and the Red is the high side. The silver caps are for the valve stems that have to be opened on the Supply side to fill and the high side to test.

Your Freon can might not have had enough internal pressure to fill the system.

[Fake Name]

When I build the system in Yellow Brute I am going to make it like a modern system with R-134, Sight Glass, Filter and low pressure cutout and Wide open throttle cutout.

Something else to consider (although you probably already thought of it)- if you're going with electric engine fans, be sure to install an over-pressure switch to kick the fan in. After installing my Classic Air System, I was lucky enough to take it to a AC specialist for the evac/fill. He caught the problem right away. It's possible for the AC to get hot without the electric fan (engine temp switched) running. No fan=no cooling for the AC condensor=high pressure and possible seal/compressor failure.

Conventional fans are not a problem, as they are always turning with the engine.

Now, back to the original problem....


fn

[kid]

Actually I tie my 10" fan to the AC Pressure switch and to a 190 degree thermostat.

[Fake Name]

Yup, my dual 11" are set up the same way.

fn

[ToughOldFord]

Any thoughts on this condenser? Good, bad, or indifferent? Is that a fair price? He has the dimensions I'll need.

http://cgi.ebay.com/ebaymotors/ws/eBayI ... mot_widget

[ToughOldFord]

It should fit pretty good. I have plenty of unused radiator support on both left and right side so fabbing brackets should be easy. The thickness of this one is ideal, as I have 1 1/2" max to work with so the 3/4" he's selling will give me some extra room to work with. Others I've found on ebay are 2" thick and that won't work at all.
Sounds like the price is right though, I wonder what the quality will be? I might give it a try then and find out.

[kid]

NAPAs was Generic but the Ford correct size and Checker was showing several sizes.

[basketcase0302]

ToughOldFord,

A/C guy here too, (since 1976). Thinkin bout' changing trades some 30 years later!

the procedure said that after you open the can of freon to the system to run the engine at 2,000 RPM for a couple of minutes.

When you rev the engine the low side(suction side) will pull down. (The pressure will drop on your gage). This will make it easier to add freon in the low-pressure gas form.

P.S. One very important part of the system is to match the TXV or expansion valve to the evaporator in terms or B.T.U.'s
Every drier that I've ever dut-open has a built-in screen for the larger, (metal filings, etc.)
Like Kid stated, the dessicant just removes any moisture from improper servicing or non-sufficient evacuation.

Hope this helps.

Basketcase