1985 911 Targa Air Conditioning

[Brian_911]

OK, I am moving from Washington to Georgia and I need to get the AC fixed. AC has not worked since I bought the vehicle. A couple of questions:

1. The wire going to the clutch on the AC compressor is disconnected. The only control I see inside the vehicle is a lower center console blower control switch with four speeds and off. Is my assumption correct that the solenoid power gets energized with turning on the blower? I do not see any "thermostat" type controls. Good news is at least the blower functions.

2. If I have a vacuum test on the car and by some miracle it holds, should I just have them charge it and hope for the best?

3. If I make a transition to R134, does the whole system have to come out? What components require replacement?

Thanks for the help,
Brian

[Brian_911]

These "LOOK" ok.
Brian

[dshepp806]

What part of GA. are you heading to?

Best

[rlh930]

My situation was similar to yours: my AC no longer cooled. The mechanic determined that all the R12 had leaked out over time, but that the system basically held pressure and could be fixed. He replaced the drier (he said this had to be done because of the complete loss of coolant) and filled with R12 (this was a few years ago). Everything worked fine for a year or so, but eventually the R12 again leaked out and the AC is again inoperative.

I think at the very least you will end up having to replace all the hoses with new barrier hose. The real solution, given your move to the Southeast, is probably to go to the Griffiths replacement system (www.griffiths.com).

[Crachian]

RE: #3

No, you don't have to remove anything to evacuate and recharge just to see if the system will work and you don't have any catastrophically-failed components. But even if it works, you're probably going to be back in there soon to upgrade.

[scottb]

Originally posted by Brian_911
2. If I have a vacuum test on the car and by some miracle it holds, should I just have them charge it and hope for the best?

Even if the car holds a vacuum for an hour, that isn't definitive with regard to the system holding freon. This is because the original hoses were designed to leak and, over time, they will do just that. And there goes your expensive and ozone-depleting R12.

If you're serious about your a/c, do a search on the board for posts by Jim Sims, Hugh R., me, and others. Jim Sims is really the a/c guru on the board, and he's posted a bunch of stuff that's very useful. At the very least, you'll want to replace your original hoses with barrier hoses that don't leak. Then you'll need to replace the receiver/drier, and then you're on the slippery slope we've all been on at one time or another. There are several useful mods that you can you can do yourself...barrier hoses, Griffiths center vent, additional condenser with a fan, ProCooler, etc.

On the other hand, if you don't want to spend serious cash on a/c, then consider just replacing the receiver/drier and migrating to R134. You'll have to top-off the system pretty regularly due to the original hoses leaking, but at a cost far lower than R12. With a stock system and R134, you'll get mediocre cooling, at best, which I suppose is better than nothing.

Scott

[Jim Sims]

"then consider just replacing the receiver/drier and migrating to R134."

The refrigerant (compressor) oil must also be changed. Since the system is open I would also flush the deck lid and front valence (chin) condensers of the R-12 refrigerant mineral oil.

[scottb]

Originally posted by Jim Sims
"then consider just replacing the receiver/drier and migrating to R134."

The refrigerant (compressor) oil must also be changed. Since the system is open I would also flush the deck lid and front valence (chin) condensers of the R-12 refrigerant mineral oil.

Jim: I was using "migrating to R134" as shorthand for what you described.

A competent a/c shop will be able to "migrate" you properly, and if you're not familiar with doing a/c work you should strongly consider having a professional, at the very least, evacuate and charge the system (after, of course, you've flushed the system and changed the oil yourself).

[futuresoptions]

Converting to 134a is not as big a deal as what the a/c industry would like you to believe. I have done several 134a conversions, and have had great sucess with them. You are recommended to change out your condensors, evaporator, drier, lines and compressor when doing a full conversion, but in most cases this is not cost effective. what I have found is if you remove your compressor and drain the oil, measure the amount that came out.
flush your a/c lines with 134a. get and idea of how much oil comes out of the lines. reinstall new drier and 134a metering device (crucial in most cases) reinstall new synthetic oil. and charge system with 80% of factory charge with 134a you will have no problems. if your system has oring type seal, i recommend them being changed out with the green orings, I believe they are called viton but I may be wrong. you will have no
problems. If your vehicle originally used 4pds of refrigerant from factory you will only charge 3.2pds aprrox of 134a. The most inportant step you can do for yourself when doing the changeout is to pull a good vacuum on the system ovenight before adding refrigerant. most mechanics will tell you this is not nescessary, but time is a factor that most a/c mechanics will not put into their service. Your system performance depends on the removal of non-condesables, and by doing the vacuum you are removing them and any moisture out of your system that you can. also before you put your orings on if required, put a little a/c oil on them to keep them fresh, and to help them seal.

[BReyes]

Great advice above. I would recommend you pull all the a/c lines, have a hydraulic hose shop (like Amazon hose) rebuild them with new hoses. They will have the green o-rings. Order a receiverdryer from our host and a procooler from Griffith. No one has mentioned replacing the expansion valve (shown in your picture above - its under the tar pad ) which is hard to get to because hard to get the evaporator out/in.

Curious to hear from others here, if they too have replaced the compressors on 134 conversion.

Regards,

[futuresoptions]

Expansion valve is your metering device, some vehicles will have an expansion vavle, other vehicles will have a device with a screen called a fixed orifice. If you have an expansion valve on your vehicle you will need to purchase one that is used on 134a vehicles. in normal operation an expansion valve will limit the flow of refrigerant to the evaporator to try and maintain certain tempeature/pressures. The pressures needed for 134a versus r12 are different thus the need for the new expansion valve. I have converted vehicles for a couple friends that did not want to spend the extra ten dollars for their fixed orifice and the change outs just didn't work until the new fixed orifice was purchased. The pressures just wouldn't get to the point that they needed to start cooling at. However I have changed out systems without changing out the expansion valve and they ended up working just fine. You can try charging it without changing the expansion valve, but if it doesn't work your looking at more time and more expense. I would recommend changing the expansion valve because of this reason, also most expansion valves will have a catch screen that accumulates system debis (small pieces of metal etc...) to keep the valve moving freely. To do the job correctly would mean less headches and years of trouble free service.

[scottb]

Originally posted by BReyes
Order a receiverdryer from our host and a procooler from Griffith.

The ProCooler replaces the receiver/drier. If you're buying a ProCooler, you don't need to buy a receiver/drier also. And, Griffiths does not sell the ProCooler, but our host does.

Scott

[BReyes]

Scott Thanks for the correction.