Project Summer Comfort - Refreshing factory A/C

[Arne]

After a short drive this morning. Fan speed 2, engine 1500 RPM.

[Chuck Miller]

VERY impressive Arne !!!

[Arne]

Thanks, Chuck. The real world test will be this coming Saturday. PCA Cascade Region drive into the Umpqua Valley for lunch. Highs are forecasted to be in the low 90's. It's a drive I would be a bit reluctant to do without working A/C. But with this, I suspect I can keep the cabin temps easily in the 70's. Will need to watch the oil temp, though...

[Arne]

The jury is still out, due to a problem. I had the system charged on Tuesday the 20th. The picture in post #41 was taken on Wednesday the 21st. Yesterday (Saturday the 24th) we did a little more than 200 miles, outside temps in the 70s and 80s before lunch, and 90-95° on the way home. The A/C was not impressive on the drive, especially the afternoon leg. Was blowing cool, but definitely not what I would call "cold".

Today (Sunday the 25th), I went to take a drive in conditions similar to yesterday afternoon to try to determine if the evaporator might have been icing up. Instead I found that the A/C is not running at all today. The clutch won't engage unless I bypass the hi/lo pressure switch. So my assumption is that much of the refrigerant has leaked out. The picture with the 34.5° vent temp was after 1 day, system still had a good charge. By the drive yesterday on the 4th day, the charge was low but still enough that the pressure switch would let it run. The result was some cooling, but not up to spec. By the fifth day enough refrigerant has leaked off that the pressure switch has shut us down.

I did have some UV dye added when it was charged up, so tomorrow I'll try to get it in to have it checked for leaks with a black light wand.

[Arne]

A late follow up, here. Two problems were found by the A/C shop.

1.) There was indeed a leak, at that darned problematic connection to the expansion valve in the smuggler's box. Note to future people doing this with Griffiths hoses and evaporator - call Griffiths on the phone and see if you can have him custom build a better dryer-to-expansion valve hose. About 3" shorter, 90° fitting for o-ring, not flare. This would be far superior. (In fact, while Griffiths compressor kit #3B has hoses that will accommodate reusing several of the original components with flare fitting, if you do the package I did with new evaporator and front condenser I'd probably want to have hoses with o-ring fittings everywhere except the two for the rear deck condenser.)

2.) During the recharge process after the leak fix, we discovered that the hi-lo pressure switch had failed. While the gauges were still connected and we could see that the pressure was fine, the switch was still open, no power to the compressor clutch. Griffith includes a spare switch with the kits, but in my haste to get all the parts unpacked and such, I never saw it and apparently disposed of it with the discarded packaging. I have a replacement and spare on their way now, and the switch is currently bypassed so that the A/C will work. Nice cold air from the system.

[maxminshull]

Thanks for this thread Arne, considering improving the AC on our 72T and your insights will be invaluable!

[Arne]

Final word - PCA drive today, sunny and warm (mid-80s). A/C worked great. Started out after the lunch stop with the cockpit pretty warm from being parked in the sun. Started with temp switch about ½ way between cold and warm and fan on 2. My wife turned the fan down to 1 after about 5 minutes. Left it there the rest of the trip.

Also, oil temp never went above 220°F, even on the return trip on the freeway at 75-80 MPH.

Very pleased.

[govols!]

Glad to hear how well it is working, Arne !!

[ProfHollan]

Arne,

Want to thank you for documenting your Project Summer Comfort. Detailed information and thoughtful advice was extremely useful for installation of Griffiths system to replace the original system in my 73 911.

Thanks!
Jim