theprf

You really do need to fix the blend doors. When the foam's gone they are a piece of galvanized steel sheet that's about 30% holes. It's never going to be "cold" with that much hot air leaking in.

Ben8jam

So fully open the valve? I was reading it should only be done "slowly" but of course I don't know how slow or fast the valve lets the freon out.

Per technical difficulties: Let's just say the EPA would not be impressed... and I'm glad I wore very heavy leather fire proof gloves while working with it....

I'll try to do the rest of the 12oz can with dye tomorrow. Any idea why when the passenger side fan kicks on (high) the low side pressure drops significatinly? And then goes back up when it turns off. Can't believe i gotta start trouble shooting the fans now. They used to kick on when I turned the car off, now they don't.

Yes vents might be an issue. Heater works 100% blasts hot air. And I just replaced water pump and full coolant flush from green to pink (trying to solve why it only took 5 gallons of coolant too, fun times here in home diy garage).

allcool

As long as your set up is connected correctly to can and service port with no leaks, you can't charge to fast with those little cans in a 996. Most of the time the problem with the small cans is you can't get it in fast enough or at all.

Ok, after looking at your pic, not sure if you have the puncture type can that uses pointy needle type set up, and backing out the needle once can is punctured opens the can valve. or the self sealing can that can only use the flat nose needle that can only be used on the self sealing cans. Some of these self sealing epa can systems have funky valves that are fully open in the middle position, some in the full down position, iirr. I really don't like the new little can setups, but once understood they do work.

Bottom line, figure what setup you have and when the can valve is fully open. then use it fully open.
If you're having problems with the can/valve leaking and haven't figured out how to connect leak tight yet, don't use the freon leak dye cans as it will lightly stain anything it touches if its dripping down from a leaky can/valve/hose/etc....

Best to have a leak free charging setup before you use freon with leak dye in it... However, its a good idea for you to have some dye in there as we know you have a leak, just don't know where/how big it is and the dye will show that. Make sure to have the ac drain clear as the water/condensate that leaves puddles under you car will have dye in it if the evap is leaking...

Keep at it, you'll get it. Hopefully its a very small leak that took a long time to leak down. Or not, and you easily see the dye and change out the leaky part.

As for the vent door foam problem, wasn't asking you if your heater works. Was trying to figure a way to see how much hot air they were leaking in the cabin on full cooling mode. Hence me asking you to turn ac on max cool fan and lowest temp, then turn off the compressor * button on the control panel. Then measure vent temperature and compare it with outside ambient temps to see how much heat was being introduced by the missing foam seal. Let it run like this for a few minutes with doors windows open before noting temps.

jmo....

allcool

I'm not familiar with the vent doors on our 996, although have read about the foam problem. Seen many automotive vent doors, just not a 996.

No idea of the condition of my 996.1 & 996.2 vent door foam seals as I've never had problems or foam blowing around. But my top is down most of the time so that might blow the foam out of my car before I see it..? But both cars ac works great with mid 40° vent temps when its hot out...

So, if I understand you correctly, the vent doors have holes (30%of the doors surface area..?) all thru them like Swiss cheese and the foam covers these holes blocking air from passing thru the holes..? Any diagrams/pics of the doors we're taking about. What should i search for to see this..?

theprf

This is what the blend door looks like. The white showing through the holes is cardboard that I glued on to the opposite side. It's easy to see why the blend door does not do much once the foam is gone.

allcool

Thanks for the pic, it explains everything.

Is there a good test to see if the foam is gone.?

theprf

I suppose an endoscope would do the job. I think the temperature blend door can be easily seen from the access hole in the frunk used to change the heater core.

Ben8jam

I'm sure my blend doors are shot. But when it warms up later today plan to keep going with the can of freon.

1. I think the connection is tight, yeh don't want to be staining everything connecting the can. The gauge is a needle valve, god I just assumed the can was the same. Says is a "self-sealing can", though I'd dare not disconnect it considering the first time I connected it I froze my leather glove solid
2. Will connect it all, and turn on car. High AC (it's bugging me the front right fan isn't turning on with AC)
3. Open valve fully, rev engine to 1500ish and keep checking the PSI.
4. Cross fingers.
5. Measure vent temp with temp thermo-pen gauge. Have a infrared gun too.

Questions:
1. Is it possible to over fill the compressor? is there a symptom to look out for?
2. Why would the low side pressure drop significantly when the fan speed goes from low (don't forget low on passenger side is not running) to HIGH? (both fans work on high)
(NOTE found I have a missing relay which is why Fan 2 Low was not engaging. Popped in the high one to test, now both fans turn on low--- sheeeesh!)

Also a tad concerned that the high fans only turn on for a few seconds, even though coolant temp (via OBD) were getting up to 210F. I DID just change coolant and put in a low-temp LN thermostat. And I had the engine bay open the entire time, and read the engine bay temp can be used to trigger fan speeds.

So many questions!

JohnCA58

Here is a good chart on what a healthy A/C system reading should be.

Ben8jam

I must have checked fans at high at some point and assumed they worked. I did find low speed was not working on one side - and now like an idiot, found I'm missing the relay entirely for that fan+speed. So that's one less thing to troubleshoot!

theprf

If the system pressure get so high that it's dangerous the pressure switch will shut off the compressor. You don't want to let it get that high. Essentially if you are loading the A/C system up by running it with the doors open (or the top down, I don't have any convertibles so I never think of this) AND it's hot out, like 75F or higher, you want the radiator fans to be shifting from high speed to low speed constantly several times a minute. That's plenty enough refrigerant.
When the fans shift to high speed there is much more air over the condensers, which cools off the refrigerant more, so the pressures go down. Then when the pressure goes down the fans shift back to low speed, the refrigerant gets hotter, the pressures increase, and the fans shift back to high speed.

If you are in traffic on a hot day you should hear every car doing this.

But seriously, you really ought to get a real refrigerant gauge set. High side pressure tells the story. Sometimes you can rent them from Autozone. You can get a nice set from Amazon for about $60.
www.amazon.com/dp/B088RLQKR6

hardtailer

Found this thread when checking your profile to see what 996 you drive as I replied to 'hot engine:..'
Your valve and can are not compatible! I experienced it myself not knowing that self-sealing cans had appeared on the market and trying exactly what you did.
Your only option is to replace the valve with one for self-sealing cans. The center pin in that kind of valve moves down onto the valve in the can and opens it and the r134a then flows around it into the hose. It must stay turned down for as long as the r134a is to flow. Once done, turn the **** in order to retreat the center pin and the can will be sealed again. After that you can safely unscrew the whole valve from the can.

Ben8jam

Huh, that might explain why it seems it's going to take forever, if ever. I did empty one can successfully, but who knows what I did there.

The valve on the gauge I bough, has a needle that when turned all the way blocks the flow (in order to pierce the foil). But I guess I see your point, that if I turn it all the way OUT, then the can would seal itself.

I just searched the answers section on the product in Amazon for "self" and low and behold the seller says "no" it doesn't work with self-sealing cans. Some reviews said it work, but... sigh. I don't usually return items to amazon that I legit used, but I am going to return this one.

Thank you for the note!

allcool

[QUOTE=Ben8jam;19428924
The valve on the gauge I bough, has a needle that when turned all the way blocks the flow (in order to pierce the foil). But I guess I see your point, that if I turn it all the way OUT, then the can would seal itself.
[/QUOTE]

Like I said above, they both use a needle. But, The needles are different.
The puncture cans have a pointy needle, the self seal cans use a flat nose needle.
Look at the the end of the needle, if its sharp pointy, its for a puncture can. If it has a flat nose, its for self seal cans.