Drew_K

I just picked up my C2 after having the A/C recharged and wanted to share some vent temperature readings I took. I had the system converted to R134 last May, and the freon managed to lose about 1/4 of its charge since then.

I pulled into my garage after a long drive and set the A/C to max power and lowest temperature setting. Using my pyrometer, I got readings in the 30 degree F range (30-39 degrees) when holding the pyrometer directly in front of the vent around 1 foot away. I took a few readings from the side, so the air would't blow directly on the meter, and got consistent readings in the low 40's (F). It was around 90 degrees F when I did this.

When I put the meter directly in front of a vent (a few inches away), I got readings in the high 20's.

I'm not sure how accurate this test is, but I can say that the A/C (when fully charged) is very comfortable even during the hot Texas summer. However, it appears that I'll need a recharge every year. My mechanic checked for leaks and didn't find any, so the loss must be from seepage through the hoses etc. He said that was pretty typical for R134 in 911's.

I'm going to try the same test with our Camry (also R134), which blows VERY cold air, and I'll add the results to this thread later this week.

Hope this is useful,
Drew
92 C2

Randall G.

That's great, Drew. On my own car, I simply stick a pencil thermometer in the center vent. The lowest temp I've seen is 40.9F. Overall, the temps I've recorded are on the lower end of the factory's acceptance range. I think your car may be below the acceptance range--blowing too cold!

eddychan

I wonder if Randall can tell me the factory's acceptance range and how they take the readings.
I always find my C2's air-con is not working right but everytime the garage told me otherwise.
I will appreciate if someone can tell me the correct procedure of measuring the air-con. Also if the US model is different to ROW model...

Cheers!

Eddie from Hong Kong

Randall G.

Hey Eddie,

R-12 or R-134a?

Here are the tables for an R-134a equipped 993. Same as for an R-134a equipped 964:





As another person pointed out awhile back, there's no substitute for parking your car in the shade or covering--it will make your A/C feel much cooler. Especially if you have a black interior.

eddychan

Dear Randall,

Thanks, I shall take some measurement this weekend .
The air-con in my C2 is totally inadequate for the summer here in Hong Kong. I took mine back to the garage a couple of times and they said it was nothing wrong with it. My next possible project could be a new compressor.
Do you find yours reasonable in CA? I was in LA last year and it got very hot ( 32-33 C ) as well.

Cheers!

Eddie

Randall G.

Hey Eddie,

Yep, my A/C is more than adequate here on the coast, where the climate is mild. My thin-skinned wife is tired of me showing off how cold it blows . That said, Road & Track (or was it Car & Driver?) ran a long-term test on a '95 993. One of their complaints was marginal cooling in very hot climates. I think their particular example was Las Vegas. The A/C in a 964/993 is very good for a 911, average at best for any other car. Too much hose running to the front of the car and back to the engine, I suppose.

I've also found that the cooling feels less effective after leaving the car sitting in the sun all day. Every piece of the black interior is radiating heat. What I'm getting at is that you may be considerably cooler on your afternoon commute if you can cover your car during the day.

91C2wrencher

Eddy, back in the days when I cared if my A/C worked, it performed badly. Snooping around to find a cause I found that up in the front condenser there was a rather large three sided piece of foam lodged up in front of the coil blocking about half of it. It was an OEM piece that was used to seal the area but had come loose(unglued) and flopped up to block the coil. Removed it and tossed it, A/C all fixed. Have a good look into the front on the left side and see if that piece of foam is there.....

911 2

my 965 turbo also loses refrigerant every year and there arent any obvious leaks, im sure i read somewhere it seeps through the pipes, if you find a cure let us know as i dont fancy changing all the pipes for new non porous pipes

Metal Guru

My a/c gets so cold that I run it on it's lowest setting after the initial cooling is done.
There are a lot of mis-conceptions about R134a. It actually can remove more heat from the air than R12 but runs at higher pressure. Most shops don't have those charts that are posted above and get the charge wrong. Another problem can be a bad expansion valve. Leaks are another issue. All can be overcome by a competent shop and technician.
Something we can check is the condenser and how much trash is caught on it. When I pulled my condenser away from the body (to replace the fan ballast) a bunch of trash (leaves, sticks, dirt) that was trapped hit the floor. While I had it loose I vacuumed the face of the condenser to to remove the cottonwood seeds that were stuck in it.
91C2 is right about the seal. Mine had perished. I made a new one from some foal I had around the house. Works like a charm.
Bottom line is that every part of the a/c system must be up to snuff to get the maximum cold air.