Aircon info please
05-11-2018, 05:35 PM
#16
Rennlist Member
Thread Starter
Thanks again for everyone's comments. Yes I only have a fill can for the LP port and it has a pressure gauge. If I'm going to be doing this in the future a set of two gauges looks like a good investment.
05-11-2018, 06:41 PM
#17
Rennlist Member
John,
What do you have for a fill connection? My GTS was an early one with R12 so my gauge set is for such. The cans like you have are usually configured for 134a quick fit connectors. If so I am not sure how you can purge those. Based on Dave's comment I suspect with difficulty- presumably there will be a way to open the needle valve that or you try to manipulate it when fitting it.
If you leave the car during winter months without running the a/c that is likely the reason for gas escaping as the seal faces can and do dry out. The a/c ideally needs to be run for a minute or so every two weeks or at least that is my theory regarding good operation.
What do you have for a fill connection? My GTS was an early one with R12 so my gauge set is for such. The cans like you have are usually configured for 134a quick fit connectors. If so I am not sure how you can purge those. Based on Dave's comment I suspect with difficulty- presumably there will be a way to open the needle valve that or you try to manipulate it when fitting it.
If you leave the car during winter months without running the a/c that is likely the reason for gas escaping as the seal faces can and do dry out. The a/c ideally needs to be run for a minute or so every two weeks or at least that is my theory regarding good operation.
05-11-2018, 09:07 PM
#18
Team Owner
Hi John for leak trouble shooting I would suggest to pay attention to the hi pressure AC lines where they cross under the 14 pin connector and the radiator support. these will be the thin lines.
the 16v cars had a short piece of flex line and this would leak at the swages,
its difficult to spot due to the coolant hoses and ignition coil being mounted above the line
its tell tale will be a greasy area that has been wet with compressor oil then dirt has been blown into the oil from the fan.
You might think you have a leaking coil.
Anyway Greg Brown makes a repair for this hose and you silver solder new metal fittings onto the existing lines, then attach the new flex hose.
Of course this will require system evacuation and its a great time to refresh any other suspect parts in the system.
You will need a vacuum pump and a set of 134 AC gauages
the 16v cars had a short piece of flex line and this would leak at the swages,
its difficult to spot due to the coolant hoses and ignition coil being mounted above the line
its tell tale will be a greasy area that has been wet with compressor oil then dirt has been blown into the oil from the fan.
You might think you have a leaking coil.
Anyway Greg Brown makes a repair for this hose and you silver solder new metal fittings onto the existing lines, then attach the new flex hose.
Of course this will require system evacuation and its a great time to refresh any other suspect parts in the system.
You will need a vacuum pump and a set of 134 AC gauages
05-12-2018, 05:53 AM
#19
Rennlist Member
Thread Starter
John,
What do you have for a fill connection? My GTS was an early one with R12 so my gauge set is for such. The cans like you have are usually configured for 134a quick fit connectors. If so I am not sure how you can purge those. Based on Dave's comment I suspect with difficulty- presumably there will be a way to open the needle valve that or you try to manipulate it when fitting it.
If you leave the car during winter months without running the a/c that is likely the reason for gas escaping as the seal faces can and do dry out. The a/c ideally needs to be run for a minute or so every two weeks or at least that is my theory regarding good operation.
What do you have for a fill connection? My GTS was an early one with R12 so my gauge set is for such. The cans like you have are usually configured for 134a quick fit connectors. If so I am not sure how you can purge those. Based on Dave's comment I suspect with difficulty- presumably there will be a way to open the needle valve that or you try to manipulate it when fitting it.
If you leave the car during winter months without running the a/c that is likely the reason for gas escaping as the seal faces can and do dry out. The a/c ideally needs to be run for a minute or so every two weeks or at least that is my theory regarding good operation.
05-12-2018, 05:55 AM
#20
Rennlist Member
Thread Starter
Hi John for leak trouble shooting I would suggest to pay attention to the hi pressure AC lines where they cross under the 14 pin connector and the radiator support. these will be the thin lines.
the 16v cars had a short piece of flex line and this would leak at the swages,
its difficult to spot due to the coolant hoses and ignition coil being mounted above the line
its tell tale will be a greasy area that has been wet with compressor oil then dirt has been blown into the oil from the fan.
You might think you have a leaking coil.
Anyway Greg Brown makes a repair for this hose and you silver solder new metal fittings onto the existing lines, then attach the new flex hose.
Of course this will require system evacuation and its a great time to refresh any other suspect parts in the system.
You will need a vacuum pump and a set of 134 AC gauages
the 16v cars had a short piece of flex line and this would leak at the swages,
its difficult to spot due to the coolant hoses and ignition coil being mounted above the line
its tell tale will be a greasy area that has been wet with compressor oil then dirt has been blown into the oil from the fan.
You might think you have a leaking coil.
Anyway Greg Brown makes a repair for this hose and you silver solder new metal fittings onto the existing lines, then attach the new flex hose.
Of course this will require system evacuation and its a great time to refresh any other suspect parts in the system.
You will need a vacuum pump and a set of 134 AC gauages
05-13-2018, 09:11 AM
#21
Chronic Tool Dropper
Lifetime Rennlist
Member
Lifetime Rennlist
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John,
FWIW, filling the system is most easily done with liquid and the engine/AC system cold and not running. You may know from history how much you are adding each year. Connect the charge hose to the low-side port after purging the line with refrigerant. Easy way is to loosely connect the fitting, such that it doesn't depress the schraeder valve in the port. Open the valve slightly from the can while upside-down (valve down), and tighten the fitting only after you see cold liquid flashing to vapor as it bleeds out of the loose fitting. Open the valve the rest of the way, and use your hands to warm the can some. You just need to keep it warmer than the system temp. If you are charging from a larger container you'll need to manage the charge weight with a scale, and may need to add more heat to the container perhaps in a bucket of warm water. A small amount of heat raises the pressure enough to push liquid into the system. After you have added the refrigerant, the time it takes to restore the fittings and connections is enough to allow the liquid to gather heat from the system and flash to vapor before you start the engine.
I had an interesting reminder this week in a conversation with a member/friend who's restoring and refilling his system from the small cans. The cans are sold by volume (ounces) but we charge by weight, so the "ounces" become important. Refrigerant isn't the same density as 62º water, fluid ounce per ounce of weight. Charging by "can" ounces will always be short by weight.
FWIW, filling the system is most easily done with liquid and the engine/AC system cold and not running. You may know from history how much you are adding each year. Connect the charge hose to the low-side port after purging the line with refrigerant. Easy way is to loosely connect the fitting, such that it doesn't depress the schraeder valve in the port. Open the valve slightly from the can while upside-down (valve down), and tighten the fitting only after you see cold liquid flashing to vapor as it bleeds out of the loose fitting. Open the valve the rest of the way, and use your hands to warm the can some. You just need to keep it warmer than the system temp. If you are charging from a larger container you'll need to manage the charge weight with a scale, and may need to add more heat to the container perhaps in a bucket of warm water. A small amount of heat raises the pressure enough to push liquid into the system. After you have added the refrigerant, the time it takes to restore the fittings and connections is enough to allow the liquid to gather heat from the system and flash to vapor before you start the engine.
I had an interesting reminder this week in a conversation with a member/friend who's restoring and refilling his system from the small cans. The cans are sold by volume (ounces) but we charge by weight, so the "ounces" become important. Refrigerant isn't the same density as 62º water, fluid ounce per ounce of weight. Charging by "can" ounces will always be short by weight.
05-13-2018, 11:32 AM
#22
Rennlist Member
Thread Starter
Thanks again everyone. Stan: I checked the non-swivel joint you mention - the smaller diameter line. No sign of oily residue. My UV torch didn't seem to pick anything up.
I thought before I tried to introduce more gas into the system I would check the clutch engaged with the pressure sensor jumped and ignition switch and aircon switch were on.
What that test told me was there is an electrical fault :-(
As the car is parked at the moment I can't really get into the passenger foot well to investigate. I did install a better relay in the AC head and also a slave high currect relay to handle the high current of the clutch. I guess something has come a drift there.
I thought before I tried to introduce more gas into the system I would check the clutch engaged with the pressure sensor jumped and ignition switch and aircon switch were on.
What that test told me was there is an electrical fault :-(
As the car is parked at the moment I can't really get into the passenger foot well to investigate. I did install a better relay in the AC head and also a slave high currect relay to handle the high current of the clutch. I guess something has come a drift there.
05-13-2018, 12:38 PM
#23
Team Owner
OK so start under the hood remove the cowl cover then find the freeze switch, its on the front side of the blower duct,
turn on the AC,
see if one of the wires has 12V, it should,
and then check the freeze switch to see if it has continuity it should.
No power then go to the fuse panel
turn on the AC,
see if one of the wires has 12V, it should,
and then check the freeze switch to see if it has continuity it should.
No power then go to the fuse panel
05-14-2018, 01:24 AM
#25
Rennlist
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The vast majority of "conversion" leaks come from the conversion fittings. Spray some soapy water around these fittings, when the hoses are removed.
If it exists in the UK "Mr. Bubbles" works great!
If it exists in the UK "Mr. Bubbles" works great!
Last edited by GregBBRD; 05-14-2018 at 01:57 AM.
05-14-2018, 01:38 PM
#26
Rennlist Member
Thread Starter
I found the problem was a poor crimp (made by me) on one of the wires to the slave compressor solenoid relay :-( I noted that sometimes the clutch takes a few seconds to engage so I guess the pressure must be very marginal to activate the low pressure switch.
.Next time I will measure the low side pressure and attempt to top up with the STP kit I have, I will purge the hose and try to connect is while gas in coming out.
.Next time I will measure the low side pressure and attempt to top up with the STP kit I have, I will purge the hose and try to connect is while gas in coming out.
05-14-2018, 08:50 PM
#27
Chronic Tool Dropper
Lifetime Rennlist
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John, as Fred shared the at rest system pressure is temp related, and will be the same unless there’s almost none left in the system. The gauge on the little top up kit helps only when the system is running.
05-15-2018, 05:02 AM
#29
Pro
Hi John
It might be worth checking whether there is any movement in the large bore barrier pipe which connects to the hard metal line that leads to the fuel cooler. I had a very slow pressure drop coming from my system both before and after carrying out extensive work on the AC system.
When I inspected the that pipe I found I could swivel (with moderate effort) the end that connects to the hard line. There was no oily residue but I believe that to be the ultimate source of my leak.
I was advised any movement in these hoses = leakage.
It might be worth checking whether there is any movement in the large bore barrier pipe which connects to the hard metal line that leads to the fuel cooler. I had a very slow pressure drop coming from my system both before and after carrying out extensive work on the AC system.
When I inspected the that pipe I found I could swivel (with moderate effort) the end that connects to the hard line. There was no oily residue but I believe that to be the ultimate source of my leak.
I was advised any movement in these hoses = leakage.
05-15-2018, 05:25 AM
#30
Rennlist Member
John,
For purposes of clarity and for those following who may not understand but would appreciate a clearer picture of what is going on in the system, my original concern for the data you presented was that if the system pressure at settle out is below the saturation pressure for the ambient temperature quoted, the implication is that the system has lost so much of its charge that it cannot support any liquid phase at that temperature and thus is left with a gas phase content only and that is now dropping in pressure as ever more gas leaks out.
If that scenario holds, then the system is basically so low in charge that really it is no longer a top up but more a "blind recharge" with no idea how much gas is in the system. If and when this happens it is far better to fully deplete the system and start from scratch as Mr Speedtoys alluded to. The equilibrium data he posted is pretty standard issue and your data point suggests that your settle out pressure is lower than the equilibrium pressure but that could be explained away by data accuracy etc thus the importance of correctly calibrated gauges. I asked if you had a gauge set because this is the only way to quantitatively understand what might be going on. With a gauge set one can tell whether the system has too little or too much gas [when operating], whether the compressor is performing correctly and whether the expansion valve is doing its job.
The problem with conversion to R134 is that as I am aware there is not an official number available as to the optimum charge weight. The WSM has a number for the GTS but that is not an identical system either [different condenser] so a notional difference. Your model year should contain 1050gms [1200gm if you have the auxiliary rear unit option] but that is for R12. The corresponding numbers for the GTS are 950/1150 for R12 and 850/1050 for the later R134 variant- read into that whatever one can.
The compressor will happily run no matter what the pressure is if the pressure switch is jumpered but the prevailing logic is that because the pressure environment is no longer sound and gas has been lost, the amount of lube in the system has also been reduced and therefore it is [potentially] no longer a secure operating scenario for the compressor thus why the compressor is "locked out". That the system uses system pressure as a "start permissive" is interesting but what number it actually uses or whether there is a logic element that looks at both temperature and pressure to ensure the system is following the equilibrium curve I do not know. Simple fact is that oil does escape with fugitive gas but how much goes with it I have no clue [maybe there is a "rule of thumb"?].
I have had my system recharged many times over the years and even today it costs me about $25 for a complete recharge including new oil [but no system flush], more if done correctly in a quality shop with a gas bottle weighing system- I suspect it will be very much more in the UK or the States and generally not worth $$$'s wise the effort of doing it myself. That being said I still wanted to give it a go as the shops do not like working on the car when it is hot [especially during the hot months]! I purchased a top up bottle containing about 1kg of gas expecting to use maybe half and it swallowed the job lot- effectively a full charge. Thus I concluded that when the pressure switch is in the trip condition there is bugger all gas left in the system. My dilemma then was whether I had enough oil in the system. I threw the dice, figured I probably had more oil in the system than really needed and concluded that when the thing trips next it will go for a recharge- given the performance is feeling a bit down at the moment, I suspect such is imminent.
The secure approach is thus to de-pressure the system, flush it out and start again with a new filter/drier.
For purposes of clarity and for those following who may not understand but would appreciate a clearer picture of what is going on in the system, my original concern for the data you presented was that if the system pressure at settle out is below the saturation pressure for the ambient temperature quoted, the implication is that the system has lost so much of its charge that it cannot support any liquid phase at that temperature and thus is left with a gas phase content only and that is now dropping in pressure as ever more gas leaks out.
If that scenario holds, then the system is basically so low in charge that really it is no longer a top up but more a "blind recharge" with no idea how much gas is in the system. If and when this happens it is far better to fully deplete the system and start from scratch as Mr Speedtoys alluded to. The equilibrium data he posted is pretty standard issue and your data point suggests that your settle out pressure is lower than the equilibrium pressure but that could be explained away by data accuracy etc thus the importance of correctly calibrated gauges. I asked if you had a gauge set because this is the only way to quantitatively understand what might be going on. With a gauge set one can tell whether the system has too little or too much gas [when operating], whether the compressor is performing correctly and whether the expansion valve is doing its job.
The problem with conversion to R134 is that as I am aware there is not an official number available as to the optimum charge weight. The WSM has a number for the GTS but that is not an identical system either [different condenser] so a notional difference. Your model year should contain 1050gms [1200gm if you have the auxiliary rear unit option] but that is for R12. The corresponding numbers for the GTS are 950/1150 for R12 and 850/1050 for the later R134 variant- read into that whatever one can.
The compressor will happily run no matter what the pressure is if the pressure switch is jumpered but the prevailing logic is that because the pressure environment is no longer sound and gas has been lost, the amount of lube in the system has also been reduced and therefore it is [potentially] no longer a secure operating scenario for the compressor thus why the compressor is "locked out". That the system uses system pressure as a "start permissive" is interesting but what number it actually uses or whether there is a logic element that looks at both temperature and pressure to ensure the system is following the equilibrium curve I do not know. Simple fact is that oil does escape with fugitive gas but how much goes with it I have no clue [maybe there is a "rule of thumb"?].
I have had my system recharged many times over the years and even today it costs me about $25 for a complete recharge including new oil [but no system flush], more if done correctly in a quality shop with a gas bottle weighing system- I suspect it will be very much more in the UK or the States and generally not worth $$$'s wise the effort of doing it myself. That being said I still wanted to give it a go as the shops do not like working on the car when it is hot [especially during the hot months]! I purchased a top up bottle containing about 1kg of gas expecting to use maybe half and it swallowed the job lot- effectively a full charge. Thus I concluded that when the pressure switch is in the trip condition there is bugger all gas left in the system. My dilemma then was whether I had enough oil in the system. I threw the dice, figured I probably had more oil in the system than really needed and concluded that when the thing trips next it will go for a recharge- given the performance is feeling a bit down at the moment, I suspect such is imminent.
The secure approach is thus to de-pressure the system, flush it out and start again with a new filter/drier.
