Air Con Upgrade

I would do a bit more research on this because even if you get it working you might be disappointed with the results. The condenser & evaporators etc are all dimensioned to work with R12 which was a much more efficient gas than R134. R12 systems filled with R134 generally disappoint.

There are (supposedly) drop in replacements for R12 - RS24 or R437a. AFAIK these are largely based on R134 so probably also not as efficient as R12 but theoretically less work to install as long as your system does not leak. Finding someone who handles then & can install them is another problem though ....

 

Great advice! Stick with R12. If you're not concerned about originality look into updating the compressor to a rotary style (Sanden), which is much smoother and more efficient. Just make sure to cap and save the original compressor for the future, when originality might pay bigger dividend$.

 

There is no R12 legally available in Europe.....

Sent from my HTC One M9 using Tapatalk

 

Didn't notice that the OP is in the UK. Agree that drop-in R12 substitutes are a better choice than 134, although if he's a DIYer it might be worth checking on the availability of R12 through "other channels".

 

Here is a little info!
http://www.ferrarichat.com/forum/boxers-tr-m/493702-512tr-ac-freon-replacement-question.html

 

To do a "simple" 134a conversion you need to completely drain and flush out the oil (not compatible) replace all of the black o-rings with green ones, replace the receiver/dryer, replace expansion valve and refill with PAG oil. You can get improved results if you also replace the condenser with a parallel flow (available in virtually any dimensions) After all that you'll probably get 55 to 60 degree output which can be okay if it's not brutally hot or the car hasn't been heat soaked in the midday sun but other than just lower temps the AC will pull a lot of humidity out of the air at least which can help if you're somewhere where it's humid. Without new barrier hoses you'll probably have to give the system a boost charge every season.

 

I understand the job of replacing the hoses is the real pain as i think they run through the bodywork and fitting is the problem.

 

It will definitely be hot. The air-con only really dents the heat even when it works, but hopefully you don't have the all leather seats ;-)

 

You might try these people who look like they are in your area and appear to know what they're talking about.

 

I think they may run through the door sills ?

 

You CAN use one of the many propane-based refrigerants - Dura Cool is one but there are several. I have used it in my 328 since I was on my "Make the AC more effective" Jihad 4-5 years ago. It works very well and is actually s tiny bit more efficient than R12. Assuming the rest of the system is in good condition, it will cool as well as the system did when new.

HOWEVER, as noted, for these old Ferraris, cooling "as well as the system did when new" translates to "not cooling very well at all."

I managed to get my 328's AC to what I would call "comfortable" for outside temps up to around 85F on a cloudless day. Beyond that and it can no longer keep the cabin comfortable. If the day is hot but overcast, it can do much better - easily into the 90's.

If you decide to try a propane-based refrigerant it is a DIY thing - at least in the US because it is not certified for auto use so no AC shop is going to install it. Interestingly, these refrigerants ARE certified for AC use in other applications and with the extensive search for "greener" refrigerants, it is believed that propane-based refrigerants will eventually be certified in the US for auto use.

Some folks will say that the propane-based refrigerants are a potential fire hazard. Maybe more than R134, I don't really know - but nowhere near the fire hazard of gasoline.

 

Don't know for the GT4, but for the 3x8s, the hoses run inside the right (our passenger / your driver's side) rocker pannel.

Rgds

 

Hi Paul , i have refilled my gt 4 with R 437A ,a very good , legal sobstiute of R 12 , no modification required , i suggest only to change the filter .
If the sistem is not defective , it works very well.
Ciao
Antonino

 

I think this was posted in another thread here. These guys may seem like hillbillies but they know AC systems and they provide what might be an interesting option for you if it's available to you: [ame]http://www.youtube.com/watch?v=dl4qOySVru0[/ame]

BTW, they make a great point about replacing Schraeder valves. They're the single most likely source of leaks and they're usually quite easy to replace so install new ones everywhere you can. Always lube the valves and any O rings with R-12 compatible refrigerant oil before installing. No need to bother with the hoses unless they're cracked.

 

That's a really interesting video and that stuff is cheaper than Dura Cool/similar products!

I did some research and it turns out, as they point out in the video, that the gas actually IS a refrigerant gas - 152A - which apparently can be charged using the same weight as the original R12 fill. DuraCool and similar gasses use a different fill weight.

Here's a listing of the gas: http://www.refrigerants.com/pdf/SDS%20R152a.pdf

Looks to me like THE way to go for getting the most out of these cars' ac systems. Yes, if I was starting my Jihad now, I'd be using this stuff!

 

Thanks for the link, Mike. I may try to compare its properties to R12 when I get back in front of a real computer. About the only potential issues I can think of with using duster as refrigerant is compatibility with various oils (which I'm almost positive is covered in detail in the epic RX7 forum thread) and the possibility that the bittering agent could cause problems. So it certainly seems worth considering in locations where R12 is unavailable, as well as potentially more effective replacement for 134a.

 

Just ran across some info which contradicts the info I found/posted earlier stating that R12/152A use the same charge weight. Obviously the amount of refrigerant in the system must be correct for the system/refrigerant used. I cannot say if the following conversion is correct or not but It was on a site. Obviously you can juggle the weight to get optimum cooling BUT one thing I haven't found anywhere yet is the appropriate gauge readings using 152A. Again, you can juggle with the fill and, once you determine the best cooling, look at the gauges and see what the readings are in both the static and dynamic mode. Then you will know for future work. But it would be easier to know the general readings you should be looking for up front. Of course, once you know the correct fill weight for whatever refrigerant in your system, the gauges are really more to show everything is working correctly than to "adjust" the amount of refrigerant.

The gauge readings ARE different for different refrigerants at their optimum fill for best cooling. R12, for example, has a considerably lower high side pressure than R134, which is one of the reasons (along with smaller molecule size) that using 134 in R12-rated hoses permeates them fairly quickly.

Here's the alleged conversion factor:

***CONVERSION FACTOR FOR R12 TO R152A(DIFLUORETHANE)

R12 CHARGE AMOUNT IN OZ X .56 = NEW CHARGE AMOUNT IN R152A
EXAMPLE: 44 OZ. X .56 = 24.64 OZ.

 

I had my 87 mondial chaged with RS 24 , worked very well

 

It's not a big deal, but you may have some issues you may or may not be willing to tackle. My experience is with the 308 GTS, but I think it's basically the same:

Running the hoses is not as hard as you think if you remove the gas tank and lube the hoses.
Crimping the connectors takes a special tool and you may not get it right the first time. An impact driver helps with the crimp tool.
Charging the system takes special tools and is not that intuitive. Getting it charged somewhere is cheap, so you may want to go that route. Otherwise get a vacuum pump and start with some leak detector.
Remember, your compressor won't start until the switches sense flow.

 

"Remember, your compressor won't start until the switches sense flow."

To amplify a bit...

The LOW pressure switch detects pressure in the system and if it is too low, it will not allow the compressor to engage at all. IOW, it functions initially on static pressure and signals the compressor that it is OK to engage, which then starts the FLOW. The high pressure switch, if present, is based on the high side pressure and usually engages to turn on a fan(s) when high-side pressure hits around 210 and may also disengage the compressor if the pressures get too high. Some systems don't use a high pressure switch at all, just turning on the fan(s) based on engine coolant temperature or turning on the AC condenser fan anytime the ac is on.

Once the compressor is engaged, if there is an insufficient charge of refrigerant, the low side pressure may drop below the setting of the low pressure switch and that switch will open, causing the compressor to disengage until the pressure rises again. Constant on/off cycling of the compressor is a symptom of a low charge of refrigerant - it's high enough to allow the compressor to start but falls below that point quickly after the compressor is engaged.

So it is essentially static system pressure that allows the compressor to start and system flow/pressure that maintains it.

Because static (and dynamic) pressure varies based on charge and ambient temp, a system that is low in charge might start up and run initially at, say, 90F ambient temp but not at 80F ambient temp. But in both cases it would be expected that the compressor would end up rapidly cycling on/off because with the compressor operating, the low side pressure would drop too low and the low pressure switch would disengage the compressor until the low-side pressure rises to the minimum.