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Ok I thought it took the Freon but today I tried to add more to reach that 37OZ and it won't go past 12OZ. The compressor will kick on for a while then kick off. The top part of the condenser gets hot but no other place will. It will blow a little cold air for a few seconds while the compressor is on and then it's off. So does that mean my condenser is clogged? Does my 928 have an orifice tube that could be clogged? I circled in red the part that gets hot when the compressor kicks on and nothing else will get hot.
Low pressure switch is probably kicking off the compressor once it starts running and it has to be running to fill it or the pressure will be way to high.
Once you glcsn keep the compressor running, also check the temperature of the lines on the input side and output side of the expansion valve. Those are a common failure when the pressures are right, the compressor is running and you don't get coldness out of the vents.
Low pressure switch is probably kicking off the compressor once it starts running and it has to be running to fill it or the pressure will be way to high.
So does that mean it's stuck somewhere? I'm thinking of removing the condenser along with it's dryer to see where the clog is if any.
Once you glcsn keep the compressor running, also check the temperature of the lines on the input side and output side of the expansion valve. Those are a common failure when the pressures are right, the compressor is running and you don't get coldness out of the vents.
Apologies for sounding a bit brutal but at the moment I rather suspect you are pissing in the wind if you think you are oging to get this system working afte being sat for 15 years and changing nothing out [assuming that is an accurate understanding].
The filter drier and the expansion valve are service items and have to be changed out from time to time. I rate the expansion valve as being good for 10 years after that who knows. If the expansion valve is changed out the filter drier has to be changed once the system is opened up. The compressor seal can fail if one leaves the compressor not running over one winter season- the oil on the lip seal face dries out and when the compressor is next driven it will damage the dried out lip seal.
Evacuating the system tells you something but it does not tell you the system is gas tight- far from it. It should however hold vacuum and do so for months on end and if it does not then there is a problem of some kind.
The filter drier has a sack that holds the deliquescent pellets in place- if that fails the pellets will travel through the piping and block the expansion valve.
Chances are your condenser will not be blocked but once the expansion valve is blocked the gas cannot get through. The compressor is a positive displacement machine and if the gas cannot get through the presure wil go up and up until something goes twang or the protective systems kick in. As I am aware on my later system at least, there is a low pressure switch that has to be satisided to get the compressor to run. There is also a high pressure switch/transmitter- as the pressure goes higher it drives my electric fans faster- yourmodel does not have this so I assume it will power up the auxiliary fan and if that does not resolve the problem it will trip the ac compressior clutch solenoid to protect agianst over-pressure. Sounds as though that is whatis happening.
You are charging with R134- are you sure the system was converted to 134 when it last worked?
Given the history if you want to have a chance of getting the system working reliably I suggest you consider the following:
!. Remove the compressor and re-seal it. Have ac shop strip it and take a good look at the compressor for condition of the internals- if buggered get a new compressor. Ask them to ressure test the compressor to 250 psig or so.
2. Replace the O ring seals. For R134 the seals should be green colour- if they are black chances are they are still the R12 seals- wrong material.
3. Change out the expansion valve, the filter drier and remove the condenser to flush it and get any crap off the fins/tubes.
4. Whilst the expansion valve and compressor are out flush the evaporator and all the fixed hard lines.
5. If you find black colour O rings change out the compressor inlet and discharge hoses- either replace for new or have them rebuilt as I did with barrier hose for R134 service.
6. Fit new O ring seals after flushing.
7. Pressure test the system with air- ideally test at 210 psig but if this is not possible test to 110 psig or whatever. You may be able to pressure test the evaporator in-situ- if that does not hold pressure then fixing such is a big job as it involves dash out to repair such.
8. Fittting a new clutch/solenoid on the compressor is never a bad idea if the current one is decrepit.
9 The ac control head may have the original relay in it- if so that will probably need changing out as old ones typically conk out once they get hot.
10. The discharge line fom the filter drier is a small line as it is liquid filled. This line has a section of flexible hose in it that is nigh on impossible to replace with the engine in the car. This hose will likely [but not necessarily] be original kit. Although not barrier hose, the original mineral oil used in R12 systems will be soaked into it forming a seal. If solvent flush is passed through this line I am not sure whether the seal would be retained.
Apologies if that is not what you want to hear but it is what you need to know if you are to have a fighting chance of making the system reliable.
Apologies for sounding a bit brutal but at the moment I rather suspect you are pissing in the wind if you think you are oging to get this system working afte being sat for 15 years and changing nothing out [assuming that is an accurate understanding].
I was kinda hoping that I would get away with it.
The filter drier and the expansion valve are service items and have to be changed out from time to time. I rate the expansion valve as being good for 10 years after that who knows.
RockAuto shows the dryer is only $25 and expansion valve is $12. The dryer located in front of condenser and the expansion valve is between the front windshield and engine bay? I ordered them because it seems I'm going to discharge the system anyway.
If the expansion valve is changed out the filter drier has to be changed once the system is opened up.
Is the dryer also the filter or is that separate?
The compressor seal can fail if one leaves the compressor not running over one winter season- the oil on the lip seal face dries out and when the compressor is next driven it will damage the dried out lip seal.
Is that hard to change? I'm Google'ing seal kits and they seem to skip over the 85 year.
Chances are your condenser will not be blocked but once the expansion valve is blocked the gas cannot get through. The compressor is a positive displacement machine and if the gas cannot get through the presure wil go up and up until something goes twang or the protective systems kick in. As I am aware on my later system at least, there is a low pressure switch that has to be satisided to get the compressor to run. There is also a high pressure switch/transmitter- as the pressure goes higher it drives my electric fans faster- yourmodel does not have this so I assume it will power up the auxiliary fan and if that does not resolve the problem it will trip the ac compressior clutch solenoid to protect agianst over-pressure. Sounds as though that is whatis happening.
Yea I'm hearing a noise before it kicks off.
You are charging with R134- are you sure the system was converted to 134 when it last worked?
¯\_(ツ)_/¯
Given the history if you want to have a chance of getting the system working reliably I suggest you consider the following:
!. Remove the compressor and re-seal it. Have ac shop strip it and take a good look at the compressor for condition of the internals- if buggered get a new compressor. Ask them to ressure test the compressor to 250 psig or so.
2. Replace the O ring seals. For R134 the seals should be green colour- if they are black chances are they are still the R12 seals- wrong material.
3. Change out the expansion valve, the filter drier and remove the condenser to flush it and get any crap off the fins/tubes.
4. Whilst the expansion valve and compressor are out flush the evaporator and all the fixed hard lines.
5. If you find black colour O rings change out the compressor inlet and discharge hoses- either replace for new or have them rebuilt as I did with barrier hose for R134 service.
6. Fit new O ring seals after flushing.
7. Pressure test the system with air- ideally test at 210 psig but if this is not possible test to 110 psig or whatever. You may be able to pressure test the evaporator in-situ- if that does not hold pressure then fixing such is a big job as it involves dash out to repair such.
8. Fittting a new clutch/solenoid on the compressor is never a bad idea if the current one is decrepit.
9 The ac control head may have the original relay in it- if so that will probably need changing out as old ones typically conk out once they get hot.
10. The discharge line fom the filter drier is a small line as it is liquid filled. This line has a section of flexible hose in it that is nigh on impossible to replace with the engine in the car. This hose will likely [but not necessarily] be original kit. Although not barrier hose, the original mineral oil used in R12 systems will be soaked into it forming a seal. If solvent flush is passed through this line I am not sure whether the seal would be retained.
Apologies if that is not what you want to hear but it is what you need to know if you are to have a fighting chance of making the system reliable.
1. can't I just do this myself? What seal kit can I use?
2. I plan to remove the condenser, dryer, and expansion valve so any seals I see will be replaced.
3. That's on my list of things to do.
4. Flush with what?
5. Like rubber hoses?
6. yep
7. I'm going to pretend I didn't read that. I already had the dash out last year to fix the cracks and stuff in it. I'd hate to do that again.
8. I would clean it and refresh it if I take off the compressor.
9. I saw a video on replacing it and what to order from Digikey. I'm a computer guy so soldering is my thing.
10. That sounds scary. A rubber hose that is impossible to replace unless the engine is removed? What the hell Porsche?
I cannot comment on what you may be able to do but my assumption is that removing and replacing components will be easy for you.
When it comes to the compressor the ability to tell whether it is knackered or viable is a bit more tricky. What I can advise you is that they are generally reliable for up to 100k miles and after that pot luck as to how long they last beyond that - invariably folks will have different experiences as the effective half life drops and different units have different run times. As I understand the 928 used three different types of compressors- I am familiar with the 10PA20C. The model before that one can change the seal without disassembly- I suspect this is what you have- and as i understand, the first iteration models are more difficult to work on. If you know what you are looking at and are capable strip it down and take a look.
Replace all O rings period- it is easy and cheap to do. R12 used black coloured rings, R134 green coloured rungs to distinguish. The recommended practice after flushing is to change all o rings anyway to avoid degradation from the flush agent.
The flush media is either purchased as such or one can make one's own with a bit of research. This needs a flush gun and an air supply to drive it.
That Porsche made that short section captive beggars belief but it is what it is. I still run with the original hose section and my GTS was originally kitted with R12. One our friends recently suggested running a new hose from the filter drier on to the expansion valve. This is quite easy if you only have a front AC but not so if you also have a rear ac by any chance.
Yes, I had to replace the one in my 81. Would get cold on the one side but not make it through. Replacing it (which is fun BTW) and then recharging the system got mine working.
I cannot comment on what you may be able to do but my assumption is that removing and replacing components will be easy for you.
Just replaced the trans on my C5 Corvette which took me 11 hours straight to do. Never did a trans before and not a mechanic, so I'm pumped. Also my body hurts. If I fail the worst is that I need to buy another compressor, which might be the case anyway. RockAuto has a Denso for my 928 is $425 so not cheap. Surprised there's a Denso for the Porsche.
When it comes to the compressor the ability to tell whether it is knackered or viable is a bit more tricky. What I can advise you is that they are generally reliable for up to 100k miles and after that pot luck as to how long they last beyond that - invariably folks will have different experiences as the effective half life drops and different units have different run times. As I understand the 928 used three different types of compressors- I am familiar with the 10PA20C. The model before that one can change the seal without disassembly- I suspect this is what you have- and as i understand, the first iteration models are more difficult to work on. If you know what you are looking at and are capable strip it down and take a look.
I was looking for the seal kit for it but now that you say there's 3 possible types I'm probably just gonna wait and see if the compressor compresses.
That Porsche made that short section captive beggars belief but it is what it is. I still run with the original hose section and my GTS was originally kitted with R12. One our friends recently suggested running a new hose from the filter drier on to the expansion valve. This is quite easy if you only have a front AC but not so if you also have a rear ac by any chance.
Lucky for me there's no rear AC for the back seat. I don't think it leaks but you never know. I'm afraid the more I get into the AC the more I'm gonna hate it.
Got the condenser and expansion valve out. Doesn't look like a human was here since 1985, which is really amazing if I think about all the times my newer cars had bolts that snapped just trying to get them out. As you can see nobody had converted the AC to R134a. All black seals. Gonna spend more time sanding, painting, and powder coating. Not a fan of rust. Hopefully that won't take too long.
Good news is that I got the whole thing put back together and it seems to work... with some problems. By the way, don't buy the UAC EX9404C expansion valve because that isn't 100% exactly like how the original fits. I got it on there but the holes for the lines facing the front of the car were a bit more far apart than the original, and that took me over a day to get the lines hooked up. I'm not sure what's a better fit but that one is a pain. I did flush out the condenser and evaporator side with flush. New dryer went on easy on to the old condenser. Took 36oz of 134a with no problems and it blows mostly cold air. See that's the problem because it seems to blow hot and cold air at the same time. Seems the heater valve is bad because I took a vacuum pump and tried to see if it held vacuum and it didn't. Didn't even let the needle go up at all. Moving the controls from cold to hot will get hotter but back to cold will just get less hotter. Not sure if these devices are meant to hold vacuum but I imagine they should? I also tested the fuel dampener and that doesn't hold vacuum for very long. The fuel pressure regulator holds vacuum line a champ. I just keep finding new problems the more I look around this car.
Heater valve isn't expensive to change but looks a bit painful to get to. Just wanna make sure that it's suppose to hold vacuum. Also I'm in the market for a new fuel dampener. Spent more time sand blasting, painting, and powder coating than dealing with the AC system. Rule I have is if I remove it then I'm painting it, and replacing screws with stainless steel. I even took care of the headlight washer pump that's under the hood latching area. It works now as well as the cooling fan. Little lithium grease made it run quiet. I also used an unhealthy amount of antiseize grease, which are those silver spots you see.
Here's the before.
Last edited by dukenukemx; 03-31-2022 at 07:11 PM.
Good catch on the heater valve. I can't speak to the 1985 model year, but on the 1987 the heater valve is easy to replace. If I remove the air filter box (two 10mm nuts from inside the lower filter housing) the valve is easy to access.
It's compatible with all metals and uses. So, you don't have to stock or select different anti-seize compounds for different uses and it is rated for high temperature use up to 2,000F.
The system needs a thorough clean out and new hoses to use R134a. If you haven't converted the hoses to R134a compatible, it will all leak out. I think you need different oil for R134a that isn't compatible with R12 oil. From what I have read, if you mix the oils, it will probably plug the system.
Good catch on the heater valve. I can't speak to the 1985 model year, but on the 1987 the heater valve is easy to replace. If I remove the air filter box (two 10mm nuts from inside the lower filter housing) the valve is easy to access.
I found a video on how exactly it looks. I don't want to go as far as to remove all the hoses.
It's compatible with all metals and uses. So, you don't have to stock or select different anti-seize compounds for different uses and it is rated for high temperature use up to 2,000F.
Thanks, I'm obsessed with anti-seize. I know at some point I'll be back and having that on there ensures nothing is rusted stuck and I don't snap bolts.
Originally Posted by Taguid
The system needs a thorough clean out and new hoses to use R134a. If you haven't converted the hoses to R134a compatible, it will all leak out. I think you need different oil for R134a that isn't compatible with R12 oil. From what I have read, if you mix the oils, it will probably plug the system.
Most of the lines are metal and what I've been told this one rubber lines is impossible to replace without removing the engine. I did flush out the system along with the oil and put in new PAG 100 oil with dye. Which hoses need to be converted? Luckily for me R134a 12oz is only $5 at Wallmart, so it isn't a big deal to discharge and recharge the system.
First off, I am a complete noob. I'm an accountant, not a mechanic. If you see contradicting info here, listen to them because they likely have more knowledge than i.
With that said, having successfully gotten my '85's AC to work, i can genuinely say that it is a lot more work than one would think. First off, on my car, it appeared that someone just used 134a without converting it properly because the AC compressor was a gooey mess, which is the result of mineral oil and PAG oil mixing together.. The last pic on post #24 looks like the same gooey mess in the metal line, but I could be mistaken. IF that it is a gooey mess, then that is rubbery gunk floating through the entire AC system.
In my situation, I saw an amazing amount of that same gunk in the compressor when I went to reseal it. I was stunned at how rubbery everything was. It was so bad then I ended up sticking both halves of the compressor into a ultrasound tank to make sure there was no remaining residue (didn't seem to affect the mechanicals). What a mess. After that, i had a hose shop rebuild the hoses that connected to the compressor. I also decided to replace the expansion valve and drier since I didn't trust them knowing that the gummy residue had been in the system. Since everything was off, I took the opportunity of flushing all the metal lines, condenser and evaporator. By then, the pressure switch was the only part left to replace so why not.
All I can say is that once everything went back together with the correct o-rings, the system held vacuum and ran cold once it was charged.
03-22-2022, 08:30 PM
