A/C Hose Replacement Questions

[Inniswhe]

I am reassembling my 84 911 after a repaint. I would like to upgrade my A/C system ( it does not work) to 134 gas and replace necessary components.
I will not be completing the A/C rebuilt until next winter but I thought I would replace the lines since the fenders are off etc and everything is accessible.

I have a barrier hose kit from Rennaire ready to go in and a new filter dryer as well. I am looking for links to posts on the hose replacement. I can't seem to find any detailed posts on the hose replacement portion of the job.

I understand I should try and clean as much oil out of the condenser as possible , how - compressed air I am thinking.

If I am not going to complete this overhaul should I avoid connecting to the filter dryer so moisture doesn't migrate in from open hose end ?

WIll the little plastic caps that come on the hoses keep them sealed suifficiently until the system is properly evacuated and charged ?

The existing retaining clips are too large for the smaller hoses . Do people just reuse the large brackets ?

Thanks

Ross

[RSTarga]

I'd leave the receiver drier sealed until you gas up. You might need a different condensor and evaporator for r134 , it is not as efficient as r12 and requires more efficient heat exchangers and expansion valve.

[Tigerrat]

You'll want to use some sort of solvent to flush the cond and evap. But I think not the exp. valve or the comp. I think you can buy aerosol cans to do this. True 134a isn't as efficient but up where you are the existing components may be adequate. Depends on how cool you want to be. Ken

[Inniswhe]

Summer here only hits about 85F outdoor air temperature and I don't spend any time sitting in traffic so I was hoping the major components would be OK .

I assume a new compressor is probably required.

Ross

[stormcrow]

Ross,

what you need to do is purge the lines with nitrogen and cap them off. If you feel they need to be blown out, blow them out with an inert gas - argon or nitrogen. When you get ready to connect them, you will need to evacuate the system once it is together.

If you are going to convert to 134A and use the same compressor you will need to change the "O" rings in the compressor and change the oil that will be comatable with 134A unless of course, you buy a compressor already set up for 134a.

It is important to remove all the R12 oil from the system if you do a conversion. Also I wiould suggest that you insulate the evaporator coil box on the outside. HD supply sells 2" wide insulation tape. Makes a world of differnece with keeping the air cold coming out.

Steve

"A porsche does more then just go fast in a straight line"

[Barrpete]

The hose replacement is not difficult. Just dirty and tedious. basically you just pull the old one out & put the new one back in its place. The hardest part is the left front fender well because you'll need to remove the washer tank and then snake the hoses around the bumper shock to access the front condensor. Tie a length of cord on the old hoses before you pull it out and it will be a bit easier to pull them back through. If you have reduced diameter barrier hose it will fit back in a lot easier. The other part that was a bit of a pain was removing the old hose from the rear passenger side, it was wedged in there pretty tight. I just cut it and that made it easier.

You probably should replace at least the evaporator if you're switching refrigerants. The expansion valves are different for R12 and R134. And the evaporator is the most difficult piece to get to if you ever decide to upgrade. A new serpentine evaporator will be more efficient as well. For the same reason make sure the fan is working properly so you don't have to go back in there later.

You can get loop straps of the proper size from places like McMaster-Carr http://www.mcmaster.com/#steel-loop-straps/=2ej8su

[Inniswhe]

OK Some good points but I am a little confused.

Access to the front fenders is no issue as the fenders are off and all washer tank assembly is removed - That is why I am doing the lines replacement now. I am not going to get the project completed until next winter when I will replace the compressor with the correct unit .

I will only replace the evaporator if I need to - I thought that was an optional item to replace. correct me if I am wrong.

THanks for the link on the straps, I will order some of those.

It sounds like I should install the lines now since I have easy access and not bother connecting anything now if I am not ready to complete the entire project . Is that correct ?

I can leave the condensers off the car until I am ready to complete but they are now open to atmosphere and old oil will run out. Can they get damaged just leaving them like this or should they be solvent cleaned charged with nitrogen and capped asap ?

It does not appear that the rennaire lines are charged with a dry nitrogen charge the way they are shipped. They just have plastic caps in the ends but no pressure so I am assumming these are not dry. THese will be sitting in place on the car for several months with these plastic caps in the ends , probably just duct taped over . Is that OK ?


Keep in mind the only reason I started this hose replacement is the fact the car is apart for painting. THe A/C upgrade completion will be next winters project after the car is back together.

Thanks for all of the help.

[Barrpete]

If you already have the fenders removed then reassembly should be pretty easy. You also won't have the 25+ years of dirt falling on your head. You could install now or later but it would probably be easier now. Then just cap all the loose ends off so no dirt gets inside. The lines are not charged with anything they are just capped to keep them clean. Duct tape is probably a good idea if you plan on driving around before completing the project.

You don't have to replace the evaporator, it will still work with 134a. But its not that expensive and the upgraded serpentine versions are much efficient - and you can get the expansion valve for 134a.

As for the condensors I would clean them and install them now. They will be fine until you get around to hooking the rest up. Then you'll only have connections for the compressor & recievier/dryer to tape off.

[Mitch Leland]

Inniswhe,

Whether you do the hoses and the rest of the job next winter it appears to me you still don't know exactly what the finished project looks like. You have a lot of choices to make as to how much money and cold you want to spend and make. It seems to me if you're going to the trouble of changing out the hoses I would at the very least change out the evaporator and the A/C blower motor for an upgraded after market unit that will vastly improve your system. Probably the best bang for the buck you can make if you're interested in a decent working A/C system.

[914efi]

Regarding the purging, any idea if you can use gas from a MIG welder to do this? It is 75% argon, 25% co2. Sorry if this is a hijack. I was thinking of using this to make sure there was no leakdown before I paid to charge it.

Take a look at Speedway Motors, they have lots of AC hose and fittings that may be useful for rebuilding the system.

[Mitch Leland]

Regarding A/C hoses... I replaced the suction hose from my compressor to the ProCooler (front Lt. fender) which was about 13' and my local "Car Quest" house had a large A/C catalog with all the fittings and wrote up and order and I had the barrier hose the next day. I took my old hose in for a sample. It was not the smaller diameter hose, however I didn't ask for it either.

We live in a small town so they might be use to providing more services than our local "auto Zone".

[crustychief]

My.02 leave the new stuff off until you get a complete system, it is so easy a ca...... can do it..... well, when you get all the stuff, spend a weekend and put it in at once, it will not get contaminated badly that way.

[Inniswhe]

After removing the lines that snake through the front drivers fender I think it would be a royal pain to try and replace those lines after the fenders are on and the washer tank installed so as a minimum I am going to install the new barrier lines through that area and have the front condenser cleaned as it is off the vehicle right now anyway. The rear condenser is a 5 minute job to remove so I will take it as well to a local shop to get pressure tested and cleaned of the old oil.

The car will not see many miles this summer if any any I have to completely assemble it after a glass out repaint so as long as the lines are capped I do not expect much contamination will enter.

From the reading I have been doing it appears that the evaporator is probably a worthwhile replacement and since it also includes the correct Tx valve it should work better as well.

I expect that at the end of the day I will replace the lines, evaporator, compressor, and filter drier, and chage over to R134A . I hope that is sufficient to give a decent A/C system for our 85F summer temps.

[docrodg]

The biggest thing to remember is that you must vacuum purge the system. Pull the vacuum overnight at least, preferably 24 hours to ensure all moisture is out. Even if capped the moisture is there and after assembly the best thing is a nice long sucking out of the a/c just prior to charging. Find a good shop that will do the charging and talk to them about their hours, arrange to have the car be the last one worked on before they close for the weekend or Sunday, if they are open Saturday, that way it gets maximum time on the vacuum before they fill it on Monday. You can usually swing this arrangement for either no cost or a six-pack.

[Inniswhe]

I spoke to a good commercial/industrial refrigeration tech friend of mine about the R12 oil removal from the system prior to the R134A charging and he suggested I consider R414 as a replacement instead. He indicated that he used it very good results as a direct drop in replacement for the R12 in many commercial systems.

I do not see why this would no work but am wondering if others have tried this route. I have the barrier hoses so it may not require any other components replaced and he indicated that he the oil was compatible so no mineral solvent flushing was really not necessary.

Anyone out there try R414 as a drop in replacement ?? Thoughts ??

[Barrpete]

For what its worth, DuPont's website says it's not recommended for automotive applications.

http://www2.dupont.com/Refrigerants/en_CA/products/r414b.html

[Inniswhe]

Barrpete,

I saw that as well from Dupont but it is EPA approved for automotive use and is being marketed by Icor as "Hot Shot" specifically targetted for automotive applications.

This is why I thought I would see if anyone has tried it in a 911 system.

Ross