Air Con

[Jack K]

Is the air con in the '89 Carrera supposed to be better than the '82 SC?

I have had the Carrera for abt 5 months and now that summer has arrived here, I can't say I feel a significant difference. The larger side vents, though, are a definite improvement.

I checked with the previous owner who told me that he had a new compressor and also a new receiver drier installed abt 2 years ago and that the gas was changed from R12 to a non ozone gas.

Any feed back would be appreciated.

[jmohn]

I was given to understand the "newer" AC systems (I've got a '78 SC, so yours is a lot newer) were better mostly because of improved (larger) vents, which provided improved airflow (are your blower fans working OK?). Which "non ozone gas" was the system switched to? Was it done correctly? This is an important question. Just a point of information, if the system is intact and was (properly) switched to 134a, you should get adequate (not great) cooling, if the charge is correct. 134a is very sensitive to the amount of charge in the system, any good AC shop should be able to "fine tune" it for you. I see you're located in Australia so your system may have been switched to something I'm not familiar with. As a simple check, take a drive with a digital thermometer hanging in the center vent; with the control on full cold and the fan on medium speed you should (eventually) see about 50 degree (F) vent air or colder (assuming the outside temp is 85-90 degrees). If it's warmer than that, I think you need to have the system checked\charged\evaluated. In my '78 SC, with an after-market AC system charged with R-12, I get 48 degree vent air with 90 degrees outside temp.; with my previous 951, with the stock AC system converted to 134a, I would get 46 degree vent air on a 90 dgree day.

Look on the bright side. My car is "put away" for the winter here, at least you can drive yours.

Good luck,

Jerry M
'78 SC

[Jack K]

Jerry, tx for your reply

Your assumption was correct.

The sticker in the engine bay reads:

CAUTION - R134A
RI34A CHARGE 1200 (gms)
OIL TYPE/GRADE 1461
OIL CHARGE 150 (ccs)

The "1461" filled in wasn't all that clear - at first I thought it was "PA61"

[jester911]

In 86 porsche went to a rotary compressor that was an improvement from the old one. It still doesn't compare to most a/c systems in other cars though.
If you get the system charged it should be fine though.

[kepperly]

jack,
i would have stayed with r-12. r-134 molicules are ten times smaller than r-12 and if you had a small decrease in pressure before you will notice it really leaks through the non barrier hoses fast now! recheck your pressures.

keith

[Jack K]

Tx for the responses.

Any idea what the "A" in R134A means?

[jmohn]

Originally posted by jester911
In 86 porsche went to a rotary compressor that was an improvement from the old one. It still doesn't compare to most a/c systems in other cars though.
If you get the system charged it should be fine though.

Actually, I think the change was to a "swash-plate" design, but you're correct, certainly superior to the older piston type (which, BTW, was incorrectly sized for the system in most of these cars.

Jerry M

[jmohn]

Originally posted by kepperly
jack,
i would have stayed with r-12. r-134 molicules are ten times smaller than r-12 and if you had a small decrease in pressure before you will notice it really leaks through the non barrier hoses fast now! recheck your pressures.

keith

Keith - He bought the car with the conversion already done and re-converting back to R-12 probably isn't a very good option. While the "non-barrier" hoses used in the older systems certainly do leak 134a faster than the larger moleculed R-12, conversion of an "intact" (i.e. non-leaking) system can be satisfactorily accomplished if done PROPERLY. I agree R-12 is a superior coolant, but we have to deal with what's been done and 134a is his reality.

Jerry M

[jmohn]

Originally posted by Jack K
Tx for the responses.

Any idea what the "A" in R134A means?

Sorry Jack, I have no idea. As a further response to your original question - if your system is intact (i.e. everything functioning and not leaking any worse than when new) you should be able to get adequate (not great) cooling using 134a. If you're not getting cool air out of the vents (see my original response) then there's something wrong with the system other than using a less-effective coolant (i.e. it wouldn't be working with R-12 either). Again, the system must be "intact", no major leaks, evaporator and condensor clean and full-flowing, cooling fan (I think your's has one) on the condensor working properly, pump working properly, blower fan for the dash vents working properly, etc. If all of this is OK, then the only problem left is the amount of charge in the system. I agree with others that R-12 is a more "forgiving" and effective coolant for automotive AC systems than 134a, but we have to work with what we have and 134a can work it's just not as "easy" to use as R-12. In my previous 951, with stock system and hoses, my car could get frigid inside using 134a, however I had to add about 10-12 ounces every year due to leakage (I had to add the same amount of R-12 every year to a '79 Cadillac we had back then).

Good luck,

Jerry M
'78 SC

[Jack K]

Jerry, tx for the info.

As you said, I'm not sure why the system was changed, but it was. I happened to be speaking to the wrench at an authorised Porsche Service Shop and he told me that, from his experience, once there is a problem it is cheaper to re-gas every summer rather than to throw money at trying to fix it.

I actually haven't heard of any owners of any pre '89 P-cars that are satisfied with the adequacey of their air cons. One owner went so far as to say he was even disappointed with the air con in the 993 and that Porsche only got it right with the 996.

[CrossT]

I can sympathize. I'm dealing with a 1986 which was retrofitted with barrier hoses as well as a humongous additional static condensor under the mid front bottom of the car. I had the system charged w/R-12 and it is entirely inadequate still. I also replace a non-functional front condensor blower.

Interestingly, I get no air flow from the center vents (regardless of A/C or vent settings). Also, I have no heat. So, I'm dealing with more than just lukewarm A/C.

I hate to do it, but I'm afraid I'm looking at a trip to the dealer. At least I have my $100 PCA coupon . . .

________________________________
Todd Shallcross
86 Carrera Cpe GPW

[jmohn]

Originally posted by Jack K
Jerry, tx for the info.

As you said, I'm not sure why the system was changed, but it was. I happened to be speaking to the wrench at an authorised Porsche Service Shop and he told me that, from his experience, once there is a problem it is cheaper to re-gas every summer rather than to throw money at trying to fix it.

I actually haven't heard of any owners of any pre '89 P-cars that are satisfied with the adequacey of their air cons. One owner went so far as to say he was even disappointed with the air con in the 993 and that Porsche only got it right with the 996.

I somewhat agree with the "wrench", but what's done is done and you now have to live with someone else's decision. I agree you're system (as it is) will never be "great" but it should at least blow some cold air. The system in my SC is an after-market (the brand is "CCCCOOL" by V.P.C.) and I assure you it will dang near freeze meat. It's my (prehaps ill-conceived) opinion that the after-market systems (if correctly installed) are superior to the "factory" system. Here's a link to a discussion of Porsche AC systems (on Pelican's site) , it's enlightening :
[URL]

Good luck,

Jerry M