Neon AC compressor cycling

I don't know, the gauge I bought (At Pep Boys) only fits on the low side.

Seeing that the AC won't accept any R134, someone suggested placing the cans in the sun for a while, and the AC would accept them easier. Is this because the pressure in the can will be greater than the pressure of the AC

I think I would go with 'jumping' the switch before I would recommend setting the cans in the hot sun!

Can't imagine how he'll even get close before his spaceship burns up.....

If he jumps the low pressure safety switch, he'll be engaging the compressor with insufficient refrigerant to carry the lubricating oil (that's why the switch is there). Kiss the compressor good-bye.

Depending upon the length of his charging hose, he can;

Place the cans in a pan of hot water. Place the cans where the hot air wash off of the cooling fan will warm them up. Warm them with a hair dryer (blow dryer).

Not talking leaving the thing running via the 'jumper' for extended period here. Unless the thing is bone dry it should only need a couple minutes until it will cycle on its own. If it is bone dry than r134 is the least of his problems!

R134 generally does not escape from a sound system either - if he is low on R134 he LIKELY has a leaky condenser and/or evaporator.

On my daughter's car I replaced the condenser last summer - it was leaking - and should have replaced the evaporator as well - as it has proven also to be leaking - no more R134 in the system this spring. Nasty piece of work to replace too --- So Good Old Dad hasn't done it yet. Did replace the Radiator, which was also found to be shot when I started looking for refrigerant leaks this spring.

Well I am getting ready to do my Caravan (again) and yes I agree the stuff doesn't evaporate so it has to leak from somewhere, I just haven't determined where yet. It runs fine all summer after recharging, but this will make the 2nd time I have had to recharge after a winter of no use and still have not determined where it is leaking. Perhaps I will give the can warming method a try this time. If I can nurse through one more summer I will tear it down this fall to fix it once and for all.

This isn't related to your leak problem, but your comment about a winter of no use. Most cars owner's manuals recommend that you run the AC at least once a month in the winter to keep things lubricated. Most cars will run the compressor in defrost if you turn the temp down far enough. Otherwise, it is a good idea to turn on the AC periodically during the off season.

Matt

Given the temperature/pressure relationship of either R-134a or R-12, please explain how the compressor will even engage if the temperatures drop more than a few degrees below freezing....

IOWs, you can -try- to run your AC in the winter months if you want to but all you're doing is making yourself feel good about something that isn't happening.

Apparently you've never seen the damage that occurs to compressor pistons, swash plates, bearings, etc when the compressor has been run without lubrication for "a couple of minutes."

Do you honestly believe that there is such a thing as a perfect seal in MVAC systems?

Well, I doubt that virtually all of the car makers would recommend a practice that didn't do anything. I know my compressor will run in fairly cold weather if I simply select defrost.

Matt

Your "virtually all" is more like an old wives tale.

Well Matt, what exactly is "fairly cold?"

60*F? 50*F? 40*F? 35*F?

As air cools it becomes more dense, if the air is more dense it can not hold as much water vapor, if it can't hold much water vapor, what is the point of running the AC compressor in an attempt to dehumidify the intake air?

Read up on "Dew Point."

It looks a lot like a yellow pages ad that includes the phrase "A/C service". If you don't know what the switch looks like or where it is, then you don't know the variety and extent of damage and injury you can very easily cause in servicing an A/C system.

You can just about put money on it being the crappy evaporator if you don't have a leak in the bottom corner of the condenser. Put UV die in with the next fill, then look for the bright glow with a black-lite.

And what is the humidity/dew point when the snow on your boots melts into the floor mats, and the heater evaporates it back out? What causes the heavy condensation on the windshield/backlight when you leave the car sit? When the A/C is functional I do not have the condensation problems I have when it is not - One MAJOR reason I fixed the AC on the Trans Sport last year, and the New Yorker 3 years ago. (and why I'll likely have to fix the daughter's Neon this year)

Are you suggesting that the low pressure switch reacts to events present inside the passenger compartment Clare?

But to answer your question, if you have snow on your boots, you can be assured that the dew point is 32 or below since dew point can not be higher than ambient temperature. FWIW, a dew point of 32 is not considered to be high humidity.

Heavy condensation when the car sits would suggest temperatures well above freezing, which is not what was being claimed when Matt suggested running the AC in winter.

Then it will be a good exercise for you to switch on the AC and then go observe the compressor clutch to see if it's engaged on the next 10*F day. (hint; if it's engaged, you didn't fix it correctly)

Well, y'know, Neil, in Clare's little world -- I caught myself wondering the other day what color the sky is there -- all kinds of things are possible. The normal laws of physics and function just don't apply. Evaporators and radiators require replacement just because the condenser's got a leak, in his world, so surely it must be within the realm of possibility in that bizarre place for an MVAC LPCO to detect the dew point inside the passenger compartment.

Well both our Camaro (GM) and Caravan (Chryco) owner manuals state that the compressor will automatically engage when defrost is selected to provide more efficient operation. By the way having previously lived in upstate New York for many years where

90+ inches of snow per winter was common, I would say that cold air does a pretty good job of holding moisture :0)

Yup, automatically. (think about that) I never said that the AC compressor wouldn't engage when defrost was selected. But that doesn't mean that it will always come on no matter what the outside temperature is, because it won't if the temperature is low enough.

How can that be if it's falling out of the sky and collecting on the ground? Or are you now saying that running the AC in the defrost mode will somehow help clear a windshield covered in snow?

I'm really just trying to understand how poorly ya'all have thought this out...