Rick964

I'm looking at an 86 Carrera which has had the a/c converted to R134 but from a quick look at the reciepts for the work it seems all they changed were the drier and the fittings. Shouldn't the condensors be replaced as well? It did not seem to blow very cold which leads me to trhink that more needed to be done or maybe I should just change back to R12 if I buy it.

scottb

The oils used in the two systems are not compatible. Though you don't have to replace the condensers, you should flush the system to remove as much of the old oil as possible before recharging.

For detailed information, go to the Pelican board and search for a/c posts by "Jim Sims." He really is an expert on 911 a/c systems.

ked

the cost-effective way to see if what you've got (are getting?) works is to do as Scottb suggests - research the experts, evacuate the whole contents & reload, then check for leaks & function. I would consider loading HC-12a (Fox Tool & Supply, adv. in Excellence) - I have found it to work very well in my '87, all original components. Good luck!

ChemMan

I just saw the ad in Excellence for HC-12a. I wondered if it worked well. Thanks Ked.
Mike

wwest

Prior to the 996 no 911 A/C could really be considered even close to adequate during really hot weather. The best way to test for "proper" operation is turn the system to max cooling with the blower on the lowest possible speed. A thermometer placed in the outflow should indicate sub-45F temperatures within 10 to 15 minutes.

kuehl

Rick,
Don't know if you researched the 86 further on the ac issue, however
maybe this will help you to evaluate the a/c on the pre964's.

1) The service records which indicated a drier and charge port adapters
probably reflect a "quickey" conversion, for some reason either the owner or
tech did want to improve upon the conversion. Changing the drier with one
with the later desicannt qualifies it to run with R134a and the charge port adapters simply allow you to service the system. Basically you get a/c again however not as cold or reliable as it could be.

2) The service did not reflect a note "oil" so that is something to ponder. Though the original mineral oil which ran with the R12 "can" move through the system with R134a, it does not disperse as well. There are two major oil types that are used in the R134a converions, ester or PAG. Ester's traditionally mix better with residual mineral oil vs. classic PAGS. As a minimum service an amount of 3-4 ounces of ester should have been put into the system during the procedure. This is typically done (added) because the system is nearly 20 years old and most likely there has been oil losses, and if you don't have the complete service history on the ac you are better off adding oil; no or low oil and you will lock up the compressor. Otherwise you could liquid flush the lines, evaporator and condensers and add 6 ounces of R134a compatible oil.

3) Usually what happens, when you observe a lack of cooling, and I can't qualify what you saw at the vent without a thermometer or knowing what the ambient was that day, is the system is simply low on refrigerant. These cars have nearly 40 feet of vintage (50's) style rubber ac lines (lot's of back and forth to reach all the components). The old style hose leaks so many parts per million of refrigerant per linear foot at a given pressure and temperature. And it is a known that 911's typically had to be recharged or topped off every "x" amount of years from the day they rolled off the show room floor. The solution to that problem is to simply replace the hoses with a new style called "barrier" hose.
And while you are at it add a high low pressure switch to help protect the system.

4) You can easily figure out if the problem is related to a low charge or a component problem by simply have a tech hook up the ac gauges and compare the pressures to a P&T chart (pressures and temperatures). That will give you a very good indication to the state of charge of the system.

5) There are some other refrigerants out there you can play with however the safe route is simply R134a or R12. I'm not promoting either I'm just stating the facts for what they are: most service stations support R134a as opposed to "XY" refrigerant. If you pull into a service station and they have to remove the refrigerant from your car they (as I understand from the EPA regs. ) should have either "XY" type dedicated recovery equipment or a "trash bottle" as they say recovery can; they are not allowed to mix "XY" with other refrigerants and when it happens the tech ends up with a contaminated recovery bottle (does not make for a happy tech). So the business of servicing off brand refrigerants gets to be very expensive and troublesome.

6) Do not let the challenge of working with the 911's ac system stop you from passing up a good deal. You can get the 911's a/c system very very cold if you want (however until I pay my dues I'll have to sit back here and hold my tongue) .

Given the choice of the new model cars which have disposable engines vs. a classic 911... I'll hang back here with the classics for awhile or until the gas runs out.

kuehl

Sounds like Ron did it the right way!

redidrum

Rick,

I did my 82' 911sc completely except the condensors which were not leaking. Upgraded to Rotary Compressor, new Blower/ Fan, sealed hoses in the fwd a/c pit area, new Barrrier Hoses and connectors, new Receiver and Dryer, blocked the lower a/c vent fwd. of shifter on floor to keep all cold air on top, and had a pro a/c shop bleed down/ evacuate the system for 24 hours prior to servicing with R-134. They ran some strange fluid throuigh the system. Some folks still say that the r-12 is colder. My a/c blows cold. About a $1600 upgrade. Parts are easily available. Deduct that amount with seller if he says the car is perfect with latest upgrades.

Good Luck,

Ron

Gary R.

Disagree. Both of my 964's blow very cold air, the 91 was converted to R-134 and the 93 came with it stock. I believe the 993's system is very good also. I've run both in 100+ degree heat and have been quite comfortable. Is the A/C in the water pumpers better? I would say yes, my 997S's A/C would freeze you out on its coldest setting...

kuehl

Starting with the 964 the ac system was completely redesigned; and newer design in layout was passed along to the 993, Boxster and 996.

The primary changes were to a single condenser in the front with blower fan, change in the evaporator blower box and less rubber hose (using aluminum tubing, however still having rubber hose for flex areas; non barrier).

The 964 and forward models do blow colder than the previous 911's, however they too have their problems: leaks at o-ring connections, degrading of rubber hose sections laying on top of the engine, non-barrier hose problems, H type exp. valve, evaporator and the compressor. The compressors will lock up sooner than earlier 911's models due to lack of oil flow or low oil conditions. But, the rate of permeation (loss of refrigerant through hose walls) is much less than the older 911. So you get something better however you get some newer headaches, such as the R&R time to replace the evaporator

Rick964

Thanks for all the feedback, that is pretty much what I found from some research on the Pelican site. I had to pass on this car because of a large amount of bondo found in two different places. I'm not sure the seller knew about the crash damage, his PPI from three years ago did not point it out. There was a humongous bondo area on the drivers door - so thick that the paint guage at my shop would not even stick to it. There was also a right rear tail light replaced and bondo used to to fix up the rr quarter panel.
I'm still looking.

BTW, the a/c in my 90 C4 blows ice cold, the sytem is all original and had not had a recharge for about 3 years. I've had the car for eight years and the a/c was ice cold when I got it - I don't when it had been recharged prior to that.