993tt

Thanks guys!

I have to check if it's possible to find these tools. I have a feeling that it's illegal to do this by yourself due to enviroment hazards here in Sweden

/Erik

Randall G.

I agree with Dan, the proper approach is to let a professional shop--who can measure the amount of oil and R-134a precisely--charge the A/C. I've always wondered if you can get the proper ratio of refrigerant to oil charging the system yourself (or if the ratio is even important). A shop will also perform a vacuum test on your system. So, you'll already know if the gas is just going to leak out in one day.

That said, I plan on charging my own system soon. I've been encouraged by the number of people on the 964 board having good luck with the charge-it-every-summer-myself-for-$15 approach (in my case, my latest charge lasted two summers). In addition, the cans of R-134a usually (always?) come with the oil already mixed with the gas. If I can get a good center-vent temperature, and I have oil in the system, I should be okay.

The kit I ordered (which hasn't arrived yet) includes a gauge that can read the high-side pressure. Most the kits are only set-up to read low-side pressure. Some of the kits have an in-line low-pressure-side gauge and shut-off valve, which should at least help prevent overcharging. Of course, a gauge like Mike has can only be used with the charge bottle disconnected.

Randall G.

Oh, and another follow-up on the high-pressure gauge. As you can see in the picture Mike posted, the typical kit gauge shows up to 25 psi as being "in the green." But, the shop manual specifies a low-side pressure of 0.6 to 1.1 bar = 8.7 to 15.9 psi (at 25C, 2000 RPM). So, if you follow the generic guidance, you can put way too much gas in the system (perhaps this is what happened to Mike?). I believe that having the ability to check the high-pressure side will give me added confidence that I haven't charged too much gas. At 25C, the high-side pressure spec is 10 to 15 bar (145 to 218 psi), an easier to read spread than 8.7 to 15.9 psi on the low-end of the gauge. I'll see how it works out when the kit arrives.

BTW, nice write-up, Mike . Though, the shop manual shows a capacity of 840g (29.6 ounces) of R-134a. Where did you get 20 ounces from?

Luis de Prat

Just as a data point, I have a 21 year-old 944 in which the A/C is used year round on a daily basis, here in the Caribbean. Thus far, I've replaced the compressor, condenser, expansion valve and drier bottle, but the evaporator itself is original on the car.

Auto A/C is a major industry here in the tropics and the tech told me that Porsche evaporators very seldom go bad. Most system malfunctions are leak-related.

Several months ago I had to replace the condenser after a little mishap with a parking space marker. Like Carrera Mike, I also recharged my system with an Interdynamics kit and it's been cooling perfectly since then. Charging R134a is environmentally legal and you should have no problems doing it yourself.

Carrera Mike

I agree with you Luis. I have the same suspicion, unless evaporator is crack from an accident or an owner left the system get's contaminated and corrodes, leaks is the only one I see causing it.


Randal, Good catch, the capcity is 29.5 ounces/840 g. as per page 152 of the owner's manual. Thanks. I don't know where I got the 20.

H. Miller

I have a 96 993 with a leak. I had it charged Spring 03 and it blew cold all summer. This spring (04) it starts blowing ambient and I take it in for another re-charge. $150/re-charge done at the local P-shop. My mechanic says that the 993 has a seal problem which gets expensive and it might be cheaper to re-charge then pay for a fix.
I don't know, but it's blowing cold again and will probably only last the summer again.

Carrera Mike

You can buy the 16oz bottles which are pre-mixed with the oil lubricant.
Bottle says 14oz refrigerant and 2 oz oil lub.


Mike

Speedraser

My car's problem turned out to be a leaky and slightly loose fitting near the compressor. Charged it -- blows 48 degrees at the center vent, but the system pressure is slightly low. Hopefully, it will last for a while.

Randall G.

Follow-up on my earlier post....

I had a 'orrible evening. Received my R-134a recharge kit with low/high-side pressure gauge. The R-134 bottle is a mix of 12 oz R-134a to 2 oz. oil--the same ratio as the factory spec (840g R-134a, 140g oil). Good. But, the lowest tic on the gauge was 25 psi, way too high to measure the low-side spec of 8.7 to 15.9 psi. And, I couldn't measure high-side pressure while charging on the low-side, because I needed the same hose to connect to the low-side port. Sh****tttt. I bought the kit off the internet, and was apprehensive about what I was really getting (e.g., you couldn't read the scale on the gauge), so was half expecting to not get what I needed. Off to Kragen to buy another kit with a low-side pressure gauge.....

Got out to the car, and found that I couldn't get connected to the high-side port, anyway--not enough room for the hose with high-side adapter. Sh****tt. So, I decided to just use the low-pressure gauge from the second kit. Which also had readings in bars (nice), besides PSI (the shop manual diagram being in bars).

Start charging, running the A/C, and I notice that my condenser fan is cycling on and off. Which is surely affecting pressure that I'm trying to charge to (the diagram assumes the condenser fan is running). I digress into condenser fan troubleshooting. Yup, the (original) ballast resistor has finally died. Sh****tttt.

No way to run the condenser fan in slow-speed (short of replacing the resistor). So, I insert my trusty jumper to run the condenser fan in fast-speed, and continue on with the A/C charge. Within a short while, I have the system blowing around 48F (spec being 44.6F to 50.9F). My system only took 1 can, and there was residual pressure when I started, so looks like a slow leak (good news). I decided to take the car for a quick test drive on the freeway, to see how low the center-vent temperature would go with strong (freeway) air-flow across the condenser.

Driving down the freeway, center-vent is down to 42.9F. Nice. Suddenly, a thump-thump-thump from the rear of the car. Get off the freeway ASAP, find the right-rear tire flat. Sh****ttt. Tried to put air in the tire with the compressor, nothing happenin'. Damn, owned the car 12 years, and I've never even taken the jack out of storage (let alone installed the virgin spare). No choice, not driving home on that tire, put on the spare. After getting the tire off, find a huge gash in the center of the tread. Trash.

The tire is no longer being made. Would be okay to replace just the one tire with another model?

Phil

Randall,
I have an old s02 somewhere. If you need it, let me know.

Randall G.

Wow, that would be great, Phil! Can you ship it to me for free?

DJ

Randall,

Don't do it! Even if it's free, S02's are so worthless that you don't want it. They're worse than worthless. They actually have a negative value.

I'd ride around on the compact spare before I'd put on an S02...

SundayDriver

I agree about S-02's. I think I have one used P-Zero-C you can have - those are great tires.

JimBob Jumpback

Dagdabbit bubba randall, dont' yer go puttin no piece a crap SO2 on your porche. I gots a biased 2 ply tire dat ya can hab, jus gotta take it offa da '72 pinto stashon wagging dats ben sitin in da frunt yard fer da lasst 15 years er so. it'll werk mutch better fer ya den a SO2, wich aint even fit fer makin a decent fence und such.

Carrera Mike

Randall, Sorry to hear about your misfortune all in one day. I highly reccomend Mich Pilot Sport Rib N1. Quite and grippy for street and occasional track.

Are you saying that the fan for the condenser should be running continuosly? 'cause mine will turn on for about a minute then off when I was charging my a/c system. ~Thanks