Put the new R-134a expansion valve in and started charging. I couldn't get vent temps below 60 degree idling. I've got 50 psi low and 155 high, stays about the same on the low, but the high goes to about 180 at 2000 RPM. Deck lid closed, Kuehl type condensor in the L/R wheel well with a fan. Do I have too much R-134 in, or not enough?

Hugh,
2, 3, 4 or condenser system?
how many ounces of refrigerant?
what ambient?
what fan speed?

One full deck lid condenser, one 18" square underbelly, One sort of like yours with fan in L/R wheel well, and one stock original with three computer-type muffin fans,

About 42 ounces of R-134a,

It was about 80 degrees in the garage,

Fan on Medium then High.

I'm really stumped.

Compressor rebuilt last summer a Sanden-seiko

New hoses a few years ago.

pm sent

Life is good! 95 degrees ambient in the shade today. Went shopping today with my better half. Car sat out in full sun for several hours with windows cracked 2". Cabin temp was 136 degrees when we started out. 10 minute drive home and vent temps got down to 49 degrees on full fan speed and were still on the way down. Really amazing stuff!

Original fan motor has been squealing - it's time for replacement/upgrade. Hurricane motor from Kuehl arrives tommorow! I addition, Charlie tells me he has just come out with a next generation front condenser model - thicker but still fits in stock cage - stay tuned - more tweaks? Oh, I think so!

Fan upgrade thread here:

http://forums.pelicanparts.com/showthread.php?t=472352&highlight=wirbelsturm

Next generation front condenser thread here:

http://forums.pelicanparts.com/showthread.php?p=4790838#post4790838

Life is still Kuehl! 94 degrees on the commute home today and vent temps never exceeded 44 degrees at full fan speed! :D Oil temps are a challenge at these high ambient temps in Atlanta traffic....turned on front oil cooler override switch and it really kept oil temps from rising above 9:00 o'clock on the temp gauge.

Reviving an old thread.

One thing that I did not see in anyone's post is the modification that the old PreformanceAire did with making an additional hole in the system to provide more airflow.

Has anyone done this? Do any good or not worth the hassle?

I have one of their underbody condensors but after reading this thread am leaning towards using a newer model fender units like Kuehl or Rennaire has.

Joe A

Joe,

The previous owner of my SC installed the Performance Aire under dash vent kit. I can't compare to how it was before the mod but when my car is blowing cold (I have a slow leak and need to get it topped once a year) - it blows!! The only other update I have is a Sanden compressor, everything else is original. I'll drive the car on 100 to 105 degree days and it is plenty cold from the bulkhead vents. It's been mentioned that just the extra opening alone does a nice job with airflow, it just looks a bit unfinished.

It's not a modern Chevy or Toyota. For some reason you lose the ability to blow AC air from the dash vent. I never understood this about my car until I read that Steve Wong (who also has the Performance Aire mod) says it has something to do with the install and his is the same way.

It won't blow cold air on your face but it will cool down the rest of your body and the cabin as well. The best part is that is hidden and looks semi stock.

Also, make sure that the evaporator is clean with good, intact gaskets. The only other mod I would do to my car - other than new hoses - is the Kuehl front condenser which I am considering.

Mid August pic in driveway after 45 min hour commute home in full sun. Posted this recently on another thread but it belongs here. BTW, anyone know if there is an iPhone app for monitoring H/L system pressures? :D.

http://forums.pelicanparts.com/uploa...1285072659.jpg

"...anyone know if there is an iPhone app for monitoring H/L system pressures?"

May have a few solutions: possible with bluetooth but expensive.
How about a single LCD (or OLED) display with multiple inputs.

I've always been intrigued by the U View diagnostic system.....has pressure reading hook ups to the H/L ports.....

How nice would this look hanging from the rear view mirror? $600 :eek:
http://forums.pelicanparts.com/uploa...1285080572.jpg

$230 :eek:
http://forums.pelicanparts.com/uploa...1285080606.jpg

Good A/C upgrade info. Need to do mine before next summer. Thanks Mark Thomas!

Bump for a great thread, diving in myself this week with a Griffiths kit.

I talked with Charlie at Griffiths today and now have a solid plan for my 89 3.2. My climate is not very hot, we have a few hot days here and there. Currently looking at using old compressor (needs inspection, hopefully it has no issues) and rear desk condenser (need to leak test), new everything else and switch to R134.

good question, would be nice to have time series data on a few or more AC system attributes during a test run - wireless metering systems are getting popular but are probably a bit involved for an auto application, but who knows maybe there is something not expensive out there that an iphone can pickup. What is needed to nail down the system performance? 2 pressures, vent temp., ambient temp. ? It would be nice IMHO to be able to get enough points to plot on the pressure enthalpy chart.

More evap box clip removal tips here:

http://forums.pelicanparts.com/uploa...1328455212.jpg

http://forums.pelicanparts.com/porsche-911-technical-forum/483953-c-evaporator-box-clip-tips.html

Circlip removal.
 

Here's another idea.

Reverse the grips.

http://forums.pelicanparts.com/uploa...1328456507.jpg

All:

I just bought a bunch of stuff from Griffiths so I can have better AC. Here's what I got;

http://i125.photobucket.com/albums/p...riffithsAC.jpg

I have been disappointed with the instructions, not only the typos but the pictures aren't clear and the verbiage isn't too good either. My first step was to remove the center console (I am adding a short shift while I'm in there) and remove the switches. Then I removed the floor board on the passengers side and started working on the sensor. As was mentioned previously in this thread, the part that goes into the fire wall from onside the cabin has to stay out so the thingy in the smugglers box can come out. I had already put it back, sealed up & snug. DOH!

http://i125.photobucket.com/albums/p...Porsche021.jpg

I also removed the hood for better access.

http://i125.photobucket.com/albums/p...Porsche024.jpg

Onto my questions;

1. This silver relay shown below was unplugged. Do I have to plug it back in, and if so, which wire goes where?

http://i125.photobucket.com/albums/p...Porsche022.jpg

2. What is the part number for the smugglers box lid gasket? I searched here but couldn't find it.

I'll post my progress. To those of you who have been through this, expect lots of questions!

Cheers,

Paul.

Paul,

You bet you need that relay hooked up... W/O it your system won't work. Do you have a Bentley's manual? It has a wiring schematic which denotes which wire goes where. That relay is cheap, you can buy it at your local auto parts, I would suggest that you replace now as long as you're doing all this work.

I believe that replay is for the evaporator blower motor, but w/o that relay your compressor won't work either. I'll look up the wiring for you if you don't have it.

Mitch:

I do have the Bentley manual. I was hoping for a quick 'Red & White wire to terminal 87' answer from Griffiths, but instead they sent me a wiring schematic which doesn't answer the question, as I still don't know which wire goes to which terminal.

Thanks,

Paul.

Last Summer I drove my 85 911 to Savannah GA in AUGUST. On one day-tour on the way to lunch my wife actually asked me to turn the temp up. :D When I drove to Roebling Road for the DE I knew it was going to be a brutal hot day. I had the AC cranked up to max to soak up as much cool as possible on the trip from Savannah to Roebling Road. I got there in the morning and the roof of the car on the outside was covered in moisture. My 911 looked like a big white beer can that just came out of the fridge. It was covered in condensation. My glasses instantly fogged up when I stepped out of the car.

The AC was tested to the max on my trip home to Oklahoma. We were driving due west for many hours in the afternoon and it was 105 outside. The sun was shining into our faces and we could feel the heat of the sun on our chest. The AC kept us reasonably comfortable.

I have the system from Griffiths. 4 total condensers and the new evaporator, and all new hoses running R-12.

Nyssa...?

Paul,

Did you figure out the replay wiring? I'm sorry I was gone most of the day, then got into something else when I got home.

Mitch:

No luck as yet. Wires are yellow, black, red and red/white stripe. Terminals are numbered 85,86,87 & 30.

I'm going to tackle the upgrade of the box thingy in the smugglers box this weekend. Seems like that's the most complicated part?

Thanks,

Paul.

relays are hooked up like this, I call the two circuits the trigger side and the power side



http://forums.pelicanparts.com/uploa...1328712753.jpg

Here's a link to an '82 SC AC wiring diagram from Pelican's Tech Info Center:

http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_82SC_AC.jpg

It shows a relay with the same colored wires, 87-red, 86-yellow, 85-black and 30-red/white stripe.

You may already know this, but be careful with the white "wire" that goes into the top of the evaporator housing. It's actually not a wire at all but a tube that's part of the temperature switch. If you kink or break it you'll be looking at replacing that switch as well.

Thanks guys! I did read about the 'white wire' and have been very careful with it!

Fused relay.
 

If you replace the relay, get the fused one from our host.

Relay.
 

Here's a pic. & CKT Diagram.

The color code is at the bottom of the CKT diagram.

Good luck,

pm me as needed.

Gerry

http://forums.pelicanparts.com/uploa...1328822540.jpg

http://forums.pelicanparts.com/uploa...1328823144.jpg

red/wht - 87
red - 30
blk - 86
yellow - 85

See page 970-47 in Bentley's...

Fab'd my own evaporator block off plate
 

I pulled the evaporator box to inspect and clean while the AC system was down to replace the compressor.

Sure glad I did because the PO mechanic wrecked the install when he replaced the expansion valve. Fins were bent, thermo wire wasn't installed, no clips on the box so there wasn't a good seal. Also the evaporator rubber seals were toast.

I also found that he had cut the copper probe short, luckily I had a spare thermo wire with the right length copper sleeve and got it in at about 79 deg angle down in the core.

Looking at other threads I decided to fab my own plastic block off plate to ensure air is sucked thru the coils and not around the sides.http://forums.pelicanparts.com/uploa...1376622921.jpg
http://forums.pelicanparts.com/uploa...1376622935.jpg
http://forums.pelicanparts.com/uploa...1376622952.jpg
http://forums.pelicanparts.com/uploa...1376622978.jpg

Nice idea on the evap seal Steve. I forgot the way the system sets up --- can this be done without disconnecting lines?

Hey Karl, it could be done without disconnecting the lines. You would have to lift the evaporator and slide it in. But I was an idiot for not taking dimensions,

Installed new motor and evaporator, here's the cut out dimensions

http://forums.pelicanparts.com/uploa...1380491810.jpg
http://forums.pelicanparts.com/uploa...1380491825.jpg
http://forums.pelicanparts.com/uploa...1380491842.jpg
http://forums.pelicanparts.com/uploa...1380491857.jpg

This was an interesting quote. In conflict with others. could it be true. A big deal if it is.

Ideally, you do not want any liquid refrigerant returning to the compressor otherwise the liquid could ‘slug’ or damage the compressor. Typically, in ‘normal conditions’, this does not happen in a 911/930 because of the long run between the evaporator in the front smuggler’s box and the compressor in the rear engine bay; the hose between, 12ft+, absorbs ambient heat and tends to vaporize any remaining liquid.

Assuming ‘superheat of the evaporator’, meaning all of the liquid refrigerant has turned to vapor by the time it exists the evaporator outlet. To determine the ‘superheat’ you would note the temperature of the evaporator outlet, ie. 32F, and the pressure at the evaporator outlet, ie. 20 psi, look up the pressure-temperature correlation for R134a, 20 psi=23F, subtract the evap outlet temp of 32f by the P&T of 23F and you’d have 9F of superheat. However, the issue for a DIY to obtain the low side pressure is that they are measuring this back at the compressor rather than at the evaporator outlet which would require a service fitting at the evaporator outlet connection.

The pressure taken all the way back at the compressor inlet tends to be lower than at the evaporator outlet because of further heat absorption and friction along the way. Hence, there would be a lower psi reading at the compressor as compared to the evaporator outlet.
For example, assume the evaporator outlet is actually 30psi (on a PT chart = 35F) while the compressor is 20 psi (on a PT chart = 23F) the difference could be:
32F - 35F = -3F or
32F - 23F = +9F superheat.

Inserting a temperature probe inside the evaporator core can tell you a lot as to what is going on. If your thermostatic probe (the aluminum capillary tube sensor from your thermostat) is making good contact inside evaporator core it should be turning off the compressor when things get too cold.

PS: Ignore Willy, he is just going to mess up the thread

Good info. If someone (like me) was building a new system right now with costom hoses (like me), and was willing to put an service port fitting on the evaporator exit, would it be worth it? Would such info help everyone else to know if the R12 vs R134 expansion valve is an actual issue? Would the superheat value give a better idea of a full charge that the pressure at the compressor? Where can one find the P-T relationship for R134 (is it the standard chart that I see everywhere)? And finally, what would be the optimal superheat for our system to work for? 9 degrees? 11 degrees? What is optimal?

Since, you know, someone might be willing to actually check this...

Absent a restriction to flow somewhere in between, it doesn't seem possible to have different pressure at the evaporator outflow vs the suction line at he compressor.

Different temperatures, yes, but pressure anywhere in the return hose "volume" will be equal to the average temperature.

That seems to fly in the face of every fluid dynamic rule out there, but we'll ignore that.

We won't ignore that he also made it clear that the pressure change is attributed to the temperature change across 12-15 feet of hose...which is something that you hold near and dear to your heart, and would NEVER refute, right?

Yeah Mike, a port there would be cool, just to know. I suspect that just a few degrees like 5, certainly less than 10 is all one would want. How about it Kuehl?