Sorry, messed up the reply above. good question, I won’t pretend to be an expert so any advice is really appreciated. I was struggling to get cold air, I had it briefly and then nothing. Car had sat for 8 months over a long Swedish winter so my assumption was low on gas or something. I have a vac pump, I have enough R12 for 4 more refills and so I fully caucused the system for 2 hours. It held. I put in exactly the correct amount of R12 by weight according to the workshop manual. AC starting working immediately. My gauge showed effectively 0C at the vents after 10 minutes. This lasted about a month and 5 drives. Always had cold air immediately upon start up. Amazing. On Saturday I went for a drive. It was about 85F outside so AC was needed. For first 10 minutes it was perfect and then boom, just ambient air from outside coming in. No cold at all. I can hear the compressor click but I was wondering if I had a leak in the system.. Went home and hooked up the gauges. What I saw was the low side going down to effectively 5 pas and the high at about 210ish. Then the high would fall fairly quickly to about 180 and then start to rise again. The low would go from about 5 to maybe 8 and then go way down again. I turned off the car and waited 2 hours and the static reading on both sides equalised at 90 psi so the system is not empty. I assume ( rightly or wrongly) that the valve has something clogging it and it’s not allowing the R12 to vaporise. But maybe I don’t know what I am talking about. I assume the vacuum job I did cleared it out for the first 5 drives and then what ever was in the system has flowed back to screw up the valve. Other than that I can’t understand the low side being so low and the high side being so high ( and moving back and forth so much). Everything was absolutely perfect and working until it wasn’t…..
I bought a burned Testarossa a year ago, that's pretty good from the dash forward. I really like having a sample car to look at to see how things come apart and can quickly look at different areas to see what's involved to do certain maintenance tasks. The expansion valve is probably the hardest part to get at in the car. I HAVE my crash pad and complete dash out of this car, and I can see where the expansion valve is at. It's covered in insulation which I haven't removed yet. That insulation will have to be reapplied when your valve is replaced or you'll probably have condensate dripping onto the floor. I think you're right about your assumption on the expansion valve. Putting the gages back on and watching your low side drop certainly indicates something is plugged. There's the receiver, drier- FILTER under the hood on the passenger side of the car. Easily replaced. IF there's truly a filter in it, I'd start with that part before going after the expansion valve. I'm going to take mine out today, and cut it apart, because I AM curious what might be in it as far as a filter. My car has no refrigerant in it to lose, so I have nothing to lose taking it out and opening it up. It's a shame, anything you do, you lose precious refrigerant, unless you have a recycle machine. By law I had to have one in my shop in the eighties and nineties, but it got very little use, since MOST cars simply had no air because the r-12 had leaked out. NOW that R-12 is rare, I'm glad I still have the machine. You're NOT in a position to flippantly let the refrigerant simply escape. I can take pictures of my heater-ac unit- you won't have to blindly rip apart your car. If you have a Euro car, at least you don't have the crash pad under the dash like our US models have. So much nicer to do dash work on a Euro car. I'll poke my head into my Swiss Testarossa, and try and get an idea whether you can access the expansion valve in place. BUT you have a 512TR, which may be different than the older cars.
Thanks. I have a USA 512tr I imported from the states. Bought it from an old friend. Yes, the problem is I can’t change the dryer and then fill the car to test it. I was going to change the dryer and the expansion valve at the same time just to be safe. Curious - when I have to change to R134 eventually, do I need to change the compressor, and the dryer? So easiest to do during a belt service? I know the hoses should be replaced but is it absolutely required? And I hear r134 is heading away as well, any thoughts on what to use to replace it? ( I hear about things like freeze12 but those aren’t available in the EU….)
You can still buy cans of R12 on ebay. I would stay with that as long as possible. Changing to 134a is pretty simple and has been documented on this forum many times do a search. Unless done correctly most have mediocre results as to cooling.
So…mixing R134 w the R12 system apparently reacts with the oil used in the old system. If using r134 w the old oil…it will clog. The good news is that you can back flush your expansion valve. I know because I did it on mine. I never new why it clogged until I read somewhere about the oil. I need to remove my compressor and change out the oil type. I am by no means an AC expert but those are some things I have learned. If you understand the expansion valve you will also see how you can open certain lines and back flush. Sent from my iPhone using FerrariChat
fail Frustrating to hear, I'm certain more-so to have to fix. Was the filter/drier ever changed, and was it ever opened and exposed to the atmosphere? imho, the TXV is a part that shouldn't fail unless something in the system hurt it, like moisture. Always a good idea to replace filter drier. I think the WSM mentions replacement of filter drier with some regularity. Like an oil change. I don't do that, and never heard of that being maintained to that level. If the system is dry and hermetic to begin with, how does moisture get in? I made operational a Ferrari AC system that was partially removed and left open for ~ a decade. I was a bit anxious. It was missing the filter drier (which would have been replaced anyway) and the condenser. After sourcing new hardware, carefully re-plumbing, evacuating and R-12 charging, it was working well. I never checked Hi Lo pressures - wish I had. Those pressures sound normal, except for the fluctuations. Do you have a sight glass on your filter / drier? Anything peculiar seen? Do you see oil? Does it look normal? The WSM has some troubleshooting tips. Does it identify bad TXV for pressure fluctuations? I hope you find problem - curious if new TXV & filter-drier is the cure.
Don't forget to check your A/C cooling fans after charging the system. Mine were not working and the compressor tried to overheat because of the super high pressure, caused by the system not cooling properly.
I will of course replace the dryer ( they are hard to find but have sourced one now. I am going to bite the bullet on the expansion valve unless I cannot get it removed with the dash in the car. I’m going to try to get it our this winter with dash in. If not, I may just try to flush it.
I would be very happy if you could explain how to back flush the valve. If I cannot remove it without taking out the entire dash then I could try to back flush the thing instead. I really don’t want to remove the dash. FoA says the dash has to come out. Other guys on Ferrari list say it’s just possible to remove without removing the dash. What do you flush with, how do you do it? Happy to learn.
You know, I will double check this but I am certain I heard them. Plus the pressures are very strange. Low is down to 5 psi, the high pressure builds to about 200 and then drops and the low goes up a little and then it stops and high goes to high again. It feels exactly like a blockage between the high and low side. Remember this thing was working perfectly for 5 trips and then boom, 10 min into my last drive it went from very very cold to nada. Just like a clogged valve would do if it wasn’t letting the gas through. But I won’t pretend I’m an expert, just trying to learn as there is nobody close to me that can help.
Just an HVAC observation: The act of flushing implies 'flow'. How do you get flow across the TXV? The principle is to create a pressure drop for the refrigerant. There is a moving pintle valve acted on by a diaphragm that adjusts refrigerant flow as a Fx of evaporator temperature. As evaporator warms (refrigerant SuperHeat at exit), the valve increases flow and vice-versa. This is where the magic happens. I think you can flush the evaporator / condenser / hoses...but flushing the compressor and TXV ?? The flush fluid, I believe you would get from a refrigeration supply place. Just had a thought on source of clog... The filter driers contain desiccant which can get away from containment in system. Maybe this caused the clog and supports the WSM suggested replacement intervals (?)
Hi all, here is some information in case someday in the future it is found to be useful. The correct dryer for a 512tr ( not a Testarossa!) is RD6455 and is available from Polar Bear in Ft Lauderdale. I had help from Gretchen who went above and beyond to get me this. The correct expansion valve ( identical to the Ferrari supplied part) is EX9435C also from Polar Bear. This part is not always shown on their website but it’s identical. I would love to find an aftermarket condenser with the correct part number etc but still haven’t figured that one out……
