A/C & Duracool - Results are in! OK, but not hangin' meat yet. What's my next step?

[david914]

OK guys, after being delayed for several weeks due to special order parts, etc., I finally got the system back together and charged up. Here's the breakdown on my stock SC A/C system with a Sanden compressor:

-Removed and disassembled the evaporator box. Installed new squirrel cage fan. Old one was waaaay off balance and couldn't be fixed (believe me, I tried!). Cleaned and straightened the evaporator fins. Installed new weatherstripping to seal around evaporator core and fan to make sure air was going to be pulled through the core and not around it. Reassembled box and sealed around the expansion valve and opening in box with new Presstight tape.

-Installed new weatherstripping around condensation drain and hole that pulls air from driver's side.

-Cleaned smuggler's box, removing dirt and debris that had made its way into this area from having no seal around condensation drain.

-Installed evaporator box back into smuggler's box.

-Cleaned and resealed front condensor blower fan.

-Pulled a vacuum on system for two hours using a Robinair vacuum pump. Turned off pump and let sit for 30 minutes. No leakage.

-Charged system with Duracool. Took about three cans. Tried adding more, but vent temps started climbing back up, so I backed off.

-System pressures are ~31 lbs. low side and ~160-175 lbs. on the high side. With the fan on high, vent temps were 60 degrees with at highway speed with an ambient of 88 degrees.

Not exactly the results I was hoping for , but keep in mind this system has not been touched with the exception of the Sanden compressor and evaporator box makeover.

This is about as good as the system has ever been, but I've heard of guys getting closer to 40 degrees at the vent. I'm sure that it could be improved at least a little without adding a larger condensor. Am I right, or is this as good as I should expect without some more mods to the system? I'm wondering if a new drier-receiver and expansion valve would help. Are my pressures in line? What do you guys suggest?

[speeder]

I'm no A/C expert, but I'll give it a shot: You don't say when the last time was that the A/C was working before, the reason this matters is because there could be a blockage. The things that you have done are definitely beneficial, but you should be getting at least 20deg. cooler vent temps.

One situation that I have heard is when the filter drier is never changed it can disintegrate, and its particles can plug up the expansion valve. Some of the A/C experts here will hopefully chime in. All I can tell you is that w/ no leaks you should be colder, that info gathered from other A/C threads recently. I was actually surprised to read that some guys w/ stock SC air are cold at the vents. Do a search, these were real recent, like in the last week. Good luck!

[nostatic]

I would venture that you definitely need a new receiver/dryer, and likely a new expansion valve at the very least. My vent temps are in the 40s with new compressor/receiver/dryer/expansion and Freeze12.

Meat locker is a long way off though. Mine will get things cool/comfy if ambient temps are in the 80's. If it is higher than that, or the car has been sitting in the sun, it's more like turned me down from broil to slow roast...

[ruf-porsche]

nytime you open the system it is always a good ideal and cheap insurance to replace the receiver/drier.

[david914]

Sounds like a new drier receiver and expansion valve are in my future. Any suggestions for a good place to buy? I've seen where a couple of guys have bought from ACKits.

[stormcrow]

Three things need to be done -

Replace blower motor with a better one which delivers more CFM
Replace the Evaporator with a larger one
Install a larger condensing unit.

That's it in a nutshell.

More cfm = more airflow through the cabin
Larger evaporator = more cooling capacity
Larger condensing unit = more efficient unit

Steve

"A Porsche does more then just go fast in a straight line"

[david914]

[QUOTE]Originally posted by stormcrow
[B]Three things need to be done -

Replace blower motor with a better one which delivers more CFM
Replace the Evaporator with a larger one
Install a larger condensing unit.

That's it in a nutshell.

So what you're saying is that I need to install a tow hitch on the SC, pull a Chevy behind me with a large pipe to pump the Generous Motors cold A/C into the Porsche.

Seriously, has anybody gone through the trouble of fitting a larger blower into an SC?

[ruf-porsche]

With those type of pressure readings if you were using R12 you would be getting vent temp in the low 30's.

[david914]

The last time I had it serviced with R-12 it wasn't any colder than it is now. As an added bonus, it cost me over $250! Having read many posts here and on other boards, I'm convinced that the alternative refridgerants can and do work. Obviously, something's still not right with my system. I don't know if the drier receiver has ever been replaced on my car. I'm sure the expansion valve is original. I don't think the system has ever gotten cold enough to cycle the compressor on and off with the temperature control fully clockwise.

[ruf-porsche]

I would replace the receiver drier. Ackits has a cheap genric drier that you can use, but one of the hose will be twisted since the fittings are 180 degrees apart not like the original drier in which the fittings are only 90 degrees apart.

Vertex sells the original drier for under $100.00 the last time I order from them (sorry Wayne but your A/C site was still under construction).

When you had the evaporator out of the smuggler box and apart you should have replace the expansion valve. It's a lot of work to go back and do it, but if you're up to it I would also replace the expansion valve.

The only other item is the switch on the console with the capillary tube that sticks into the evaporator coil.

[ruf-porsche]

Originally posted by david914

-Pulled a vacuum on system for two hours using a Robinair vacuum pump. Turned off pump and let sit for 30 minutes. No leakage.

-Charged system with Duracool. Took about three cans. Tried adding more, but vent temps started climbing back up, so I backed off.

-System pressures are ~31 lbs. low side and ~160-175 lbs. on the high side. With the fan on high, vent temps were 60 degrees with at highway speed with an ambient of 88 degrees.

Although I have never use any refrigerant other than R12, reading about these "cocktail" mix it seems to me that you might had added too much refrigerant into the system.

For a stock system that has the two condensors and you are replacing the R12, the system takes approx 48oz of R12.

The people who are using propane are only putting in 12oz. And for R134a it is 36oz.

If the duracool were 16oz cans then you put in 48oz, similar to R12.

You need to find out what is the correct amount of Duracool that should be used.

[Jim Sims]

Perhaps you have too much oil in your system; how much oil was in the Sanden compressor when you installed it? Excessive oil coats the interior surfaces of the heat exchange components (condensers and evaporator) reducing heat transfer. Too little oil will starve the compressor of lubrication leading to early failure. The next time you open your system I would suggest you flush the condensers and evaporator to remove old oil. Then replace the receiver/drier (as suggested by others) and open all the hose fittings one can and drain all the oil one can out of the hoses. Then empty the compressor and start over by adding the appropriate amount of oil to it for your system. One has to remove the expansion valve in order to flush the evaporator. A new expansion valve is $30 to $50 depending on the year if ordered on line. Cheers, Jim

[david914]

Ruf, I put a digital thermometer in the center vent and monitored it as I added the Duracool. I first added one can before starting the car. Then I started the car, turned on the A/C on high and checked the vent temps. Was up in the 70's so I started adding more in small increments until it got down to around 60. Added more and it started creeping back up, so I stopped and bled off a little to get it back down. It seemed to stabilize at around 60 degrees. I dont' recall how much is in a can of Duracool, but you're right about it taking less than R-12, so I was careful to watch the temp gauge as well as the pressure while charging up.

Jim, I installed the Sanden several years ago, so I'm not sure how much oil is actually in the system as I have had it serivced by others up to this point and I don't know if anyone else had added any oil. I do know that there was some oil in the evaporator when I removed it as a couple of drips came out when I tipped it up on end (I plugged the fittings up promptly after that). I have an unopened can of R-12 oil in my stash somewhere. How do I determine how much oil my system requires? I think the Duracool has a small amount of some oil mixed in, but I'm not sure. I'll find out though. Any suggestions for "flushing" the evaporator and condensor coils? Will compressed air do, or am I looking at something more involved?

BTW, I've looked around a little bit for a new drier and expansion valve. Seems like the real cheap drier from ACKits has barbed fittings and they are 180 degrees apart like Ruf stated. Advance and Auto Zone have them listed with flare fittings, but I think they are also 180 degrees apart and would require some "hose wrestling" to make them fit. Anybody have any sources for an OEM style that doesn't cost an arm and a leg? (I need mine to to drive the 911!) The expansion valves seem to be easy to come by from several sources.

[david914]

Looked on Duracool's website. The cans are 6 ounces. Apparently there is a small amount of mineral oil in the can as well.

[ruf-porsche]

Don't use compress air to flush out your system. ACkits has a flushing gun that you can use to flush the system. Using compress air will only add moisture to the system and you will need to evacuate longer to get rid of that moisture.

The amount of oil in the condensor and evaporator is very miniscule, usually 2oz or less. Most of the oil is in the compressor.

Also did you have the rear deck down when you add the refrigerant? Although your hi pressure is within the limit of the system, having the deck up will give you a false reading for the hi side since air is not being directed through the condensor.

[david914]

I'll check the ACKits site for the flushing kit. I did have the lid down while working on the system. I checked NAPA's website for a drier and they list one as being OEM for about $25. No picture though, so I can't verify where the fittings are, but the NAPA brand has flare fittings on it. I'll keep checking...

[JR911]

David,

When I was at ACKits a few months ago I bought the recv/dryer that they sell. ($16.00)

They also have an adapter to fit on their recv/dryer so that the original style hose can be used.

Best to email or call to get exact info.

I also got a new expansion valve from them too, it was around $25.00.

They are good people to work with!

[scottb]

What's involved in replacing the expansion valve?

Thanks.

[ruf-porsche]

It inside the evaporator unit in the smuggler box. It just screw on and off, but to get at it you almost have to remove the evaporator unit out of the car.

[Jim Sims]

I have found the following A/C flush convenient and easy to use - no gun or compressed air is required - the can comes with the hose and nozzle:

http://www.acsource.com/product.asp?0=214&1=306&3=256

One can will do a 911 system (two condensers and one evaporator) if the exteriors (fins) are not too dirty otherwise two cans are required.

Cheers, Jim