A/C Charge.. Horse's Mouth

[wwest]

Apparently in '88 the compressor displacement was high enough to fill the R/D accumulator volume with a full HEAT load and even with the engine idling.

[Discseven]

Damm simplified way to check refrigerant. Am curious why all R/D's don't have the ball if that's how easy it is.

[wwest]

Originally Posted by Discseven

Damm simplified way to check refrigerant. Am curious why all R/D's don't have the ball if that's how easy it is.

With R12 or R-134a, Quick check only. There is a procedure that can be used absent the floating ball. R/D's with the floating ball are still available for our cars, I just bought one off of Ebay, likely the very same manufacturer that Griffiths sources.

Not so sure it will work at idle with your lower displacement volume Sanden even were you to use a standard fill.

[Ronnie's.930]

Originally Posted by Discseven

Damm simplified way to check refrigerant. Am curious why all R/D's don't have the ball if that's how easy it is.

Karl, notice that is Porsche's suggestion to eyeball verify that there is a minimum amount of refrigerant in the system between service intervals with a stock system (doesn't note which variety of refrigerant, however - was r12 still being used by the factory in 1988?), of course, you can bet yer bowels that a quick feel of the vent air temp will give you the exact same information.

[wwest]

Originally Posted by Ronnie's.930

Karl, notice that is Porsche's suggestion to eyeball verify that there is a minimum amount of refrigerant in the system between service intervals with a stock system (doesn't note which variety of refrigerant, however - was r12 still being used by the factory in 1988?), of course, you can bet yer bowels that a quick feel of the vent air temp will give you the exact same information.

Not so, as is I thought, well known, a low refrigerant charge often results in evaporator freeze-up, so a low vent temperature could just as well mean a marginal refrigerant charge.

My '88 Special Edition Carrera was converted to R-134a years ago.

[Ronnie's.930]

Originally Posted by wwest

Not so, as is I thought, well known, a low refrigerant charge often results in evaporator freeze-up, so a low vent temperature could just as well mean a marginal refrigerant charge.

There is a huge difference between the concept/state of low vent temp and evaporator freeze-up.

The state of charge is easily verified with an a/c gauge set and your "not so" is indicative of your lack of automotive a/c experience (sure doesn't keep you from crowing about the subject, however).

[wwest]

Originally Posted by Ronnie's.930

There is a huge difference between the concept/state of low vent temp and evaporator freeze-up.

That will take a bit of explaining.. How can it be that sub-freezing vent temperatures do not equate directly to the propensity of evaporator freeze-up?

The state of charge is easily verified with an a/c gauge set and your "not so" is indicative of your lack of automotive a/c experience (sure doesn't keep you from crowing about the subject, however).

Hooking up a gauge set is not something most of us would refer to as a Quick Check, most certainly not in the class, time consumption, of the one described.

[kuehl]

"Check the refrigerant level at least once a year because the fluid diminishes gradually during operation".
So, why does the fluid/gas disappear, into the atmosphere?
AND
Why during operation?

[billybek]

Originally Posted by kuehl

"Check the refrigerant level at least once a year because the fluid diminishes gradually during operation".
So, why does the fluid/gas disappear, into the atmosphere?
AND
Why during operation?

I had a customer years ago that was convinced by his previous service company that the refrigerant needed to be replaced every year because it ran out of BTUs....

[kuehl]

Billy,

Oh. Really. So does that mean I don't have to change the air in my tires every month?

[GH85Carrera]

When I first tried to charge my system I used the floating ball on the Receiver-dryer method. With a fully stock R-12 system I kept adding R-12 until the ball floated like described in the instructions. Then I went and looked at the gauges and the system was way overcharged. The high side was up in the 330 PSI range on a 80 degree day. I had a AC technician friend come over and we set the charge to the proper level via the gauges and it was cold again. Well as cold as the stock system can get.

Now I just totally ignore the ball. One of these days when I have to hook up the gauges again I will think to check the ball with a good pressure and temp setup. I am curious what the ball will do. With winter weather here and my AC system working normally it will not be checkd anytime soon.

[wwest]

"...system was way overcharged.....330 PSI...."


From what source did you determine that constituted an overcharge ...??

[GH85Carrera]

The pressure and temperature charts and my friend and mentors 25 years of AC service. The OAT was in the mid 80s.

[Discseven]

Will, when your 911 AC is charged to level you prefer, what high pressure do you run (and at what rpm)?