massive A/C failure questions

[tiorio]

Well, no doubt about it, I'm an Air Con - Moron...

I searched, read the posts, perused the factory manual but I ain't no HVAC expert...

Saturday my A/C in the 930, which always worked reasonably, suddenly stopped. At the next stop I found that from somewhere (most likely the rear condenser based on the spray pattern) a spray of high-pressure refrigerant/lubricant/air-con juice had escaped and desecrated my rear deck-lid by way of the rubber seal between the deck-lid and tail. High pressure indeed!

Subsequent investigation and removal of the condenser from the now zero-pressure system revealed a corroded connection which resulted in the leak.

Now the questions begin!

1) Repair or replace the rear condenser?

2) Recharge with what? Not R-12 (NLA), but what about Autofrost? Are the lines on my 89 compatible (barrier) or not?

3) How to vacuum the system, or is there a tool for the DIY'r?

4) How to recharge? Equipment needed?

5) Is this beyond the scope of a competent DIY mechanic in a modest garage?

Thanks folks! I love having somewhere to turn with these questions!

[Vipergrün]

Todd, I have parts from the AC system on my 80SC, including the compressor and deck lid condensor....plus I am close

Let me know if you are interested.

-Brad

[tiorio]

Thanks Brad! But I think the rear tail condenser is different on the 930 than on the 911, to make room for the intercooler...

Anyone else have some info?

[turbo6bar]

1) Repair or replace the rear condenser?

If the failure is in the fitting, just replace the hose/fitting. If the failure was in the condenser, replace the condenser.

2) Recharge with what? Not R-12 (NLA), but what about Autofrost? Are the lines on my 89 compatible (barrier) or not?

If I had to redo my system (R12), I'd go with propane topped off with isobutane. I'm not sure about the formulation of Autofrost. However, in a recent thread, guys can run R134 and get good performance. It is related to condenser area. More area masks the loss in efficiency in R134.

3) How to vacuum the system, or is there a tool for the DIY'r?

One time job... let a shop pull the vacuum. If you plan to do this more than once, buy a vacuum pump.

4) How to recharge? Equipment needed?

Empty system can be charged by weight. If there are modifications, then you should charge by temp-pressure. There are nice charts for charging home A/C systems, but I haven't found any good guides for charging car A/C systems. Equipment - set of gauges and appropriate fittings to fit the refrigerant you select. Be aware if you go with propane/Duracool/Envirosafe you must commit long-term. Few shops will work on a car with hydrocarbon refrigerants, from what I've heard.

5) Is this beyond the scope of a competent DIY mechanic in a modest garage?

Without the proper equipment and an understanding, yes. With the proper equipment and a mentality to do the job right (no shortcuts), no.

If you can replace a fitting, I would just do that. Replace the drier, and recharge a/c. If you want to improve performance, a rebuild/refresh is in order along with perhaps one extra condenser.

Jürgen

[scottb]

Todd:

Take a look at the parallel flow condensers if you're going to replace yours. They're reputed to be more efficient that the stock condensers. I think they're sold at www.ackits.com.

Stick with R12. It's pricey, but cools much better than 134. Most a/c shops still have it available.

Don't mess with evacuation and recharge yourself. It's a hassle, can be dangerous, and if you don't do it right you'll be unhappy with the results. Take it to a shop. Lucas Auto Air in Van Nuys did mine, and they did a very good job. Monaco Motors in Canoga Park works on P-cars, and they have a good a/c guy as well.

If you're running stock hoses, now's the time to upgrade to barrier hoses. It makes no sense to repair and recharge the system if you haven't upgraded the hoses. Changing the hoses is a DIY task, but it's a dirty job. I did mine, and I'm glad I did. I also rebuilt my evaporator box, added a condenser/fan assembly in the front left fender, and added a ProCooler.

Take advantage of this mishap to upgrade your system. New hoses, the condenser/fan assembly, and ProCooler have given me vent temps in the mid-to-high 30s. I'm very pleased with the results.

I'm pretty close to you, so if you want to take a look at my condenser/fan set-up, let me know.

Good luck.

[tiorio]

Thanks guys, this is starting to make a little more sense now...

So, anyone know of a shop in LA that's reasonable on R12 and is semi-familiar with the p-cars?

If I replace the Receiver-Dryer myself do I have to do something within 24 hours after pulling the plugs or something? Or does that apply only if the system has been used and THEN is open to air?

[scottb]

Originally posted by scottb
Don't mess with evacuation and recharge yourself. It's a hassle, can be dangerous, and if you don't do it right you'll be unhappy with the results. Take it to a shop. Lucas Auto Air in Van Nuys did mine, and they did a very good job. Monaco Motors in Canoga Park works on P-cars, and they have a good a/c guy as well.

The receiver/drier should be the last thing you replace as you're buttoning up the system.

[tiorio]

Duh...next time I'll read a little slower! Thanks Scott...

[tsuter]

Scott's Performance Aire in Anaheim... they know some things about 911s and AC.

http://www.scottsind.com/Navigation/911-914ac/911.htm

[scottb]

Performance Aire is probably the best, but they're pricey and pretty far away.

[Harold_89_911]

I think that Jason Duarte in Ventura can do repair and recharge with R12 also. He usually knows pretty well what he is doing so I would trust him with my AC for the 911.