Freon in the A/C
05-20-2004, 02:34 AM
#16
Burning Brakes
I just took mine in today to get it checkec out since it was cycling a little too frequently.
I got the same story from the A/C tech there. He said that providing my system was not leaking, he would not recommend converting to 134 until the price of R12 becomes so expensive as to be rediculous.
He evacuated my system and told me that I was down 0.8 lbs. Max charge is 2.1 lbs.
He left 30 psi of vacuum on it for 15 minutes, then released the vacuum and let it sit for 15 minutes for a leak test. It held 30 psi of vacuum for the whole time and was declared leak-free. He put my R12 back in as well as an oil charge and 0.8 lbs of additional R12 and it works like a charm.
Price for R12 at this shop was $80/lb. He charged me $64 for the extra I needed.
I'm sticking with R12.
I got the same story from the A/C tech there. He said that providing my system was not leaking, he would not recommend converting to 134 until the price of R12 becomes so expensive as to be rediculous.
He evacuated my system and told me that I was down 0.8 lbs. Max charge is 2.1 lbs.
He left 30 psi of vacuum on it for 15 minutes, then released the vacuum and let it sit for 15 minutes for a leak test. It held 30 psi of vacuum for the whole time and was declared leak-free. He put my R12 back in as well as an oil charge and 0.8 lbs of additional R12 and it works like a charm.
Price for R12 at this shop was $80/lb. He charged me $64 for the extra I needed.
I'm sticking with R12.
05-20-2004, 02:43 AM
#17
Race Car
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Originally posted by 83na944
They're not supposed to charge a leaking system. I think that's by law. And its to their advantage to charge your for repairs and then charge you $170 to charge the system, too.
They're not supposed to charge a leaking system. I think that's by law. And its to their advantage to charge your for repairs and then charge you $170 to charge the system, too.
Rock, you CAN recharge the A/C yourself. I did it last year using step-by-step instructions found by searching through old posts on Rennlist. There's also a bunch of good info on http://www.griffiths.com/ and other places like the pelican board. You'll need to obtain couple of cans of freon (not from old refrigerators) and a recharge kit -- probably some oil for the A/C system as well. I have some notes on it, and it says 33.44oz of r12 and 2.7oz of mineral oil. They can all be found on eBay. If your compressor is working, you can pump freon into the system by hotwiring the compressor -- I just used a jumper cable for that.
05-20-2004, 02:48 AM
#18
Burning Brakes
I believe it is normal for freon to leak from A/C systems very slowly through seals, etc. Can an expert confirm ?
My system was diagnosed as leak-free but was down 10 ozs. Probably had been years since it had been recharged. I think it is the larger leaks that they must fix by law before recharging.
My system was diagnosed as leak-free but was down 10 ozs. Probably had been years since it had been recharged. I think it is the larger leaks that they must fix by law before recharging.
05-20-2004, 11:51 AM
#19
Three Wheelin'
Rock:
No pun intended, but you need to cop a chill and do some reading.
First off you need to know how an A/C system is designed to work, what the individual components do, what refirgerant is currently in the system, and how to use a gage manifold.
If the system just needs to be topped off, then you can charge the system yourself. To do this you will need the correct refrigerant, and either a "cheap" one hose charging rig, or a set of gages. I prefer to use gages.
To charge the system using a gage manifold you connect the low pressure hose (blue) to the LOW pressure or suction side of the compressor. For your car the low side fitting should be at the rear of the compressor. The high pressure (red) hose connects to the fitting by the driver side cam tower. The yellow hose is normall connected to a refrigerant bottle, but in your case you remove the yellow hose and replace it with a "can-tap."
The can-tap is a short section of yellow hose with a piercing valve that connects to a can of refirgerant. Verify that the piercing valve is fully open (piercing pin fully retracted into the valve), and the red and blue valves are fully closed. Don't skip this step or you'll rupture a hose and ruin you day!
Next, disconnect the low presssure switch (located just forward of the reciever/dryer) and jumper the wires together. This is necessary because the low pressure switch controls the compressor.
With the low pressure wires jumpered and the hoses connected, start the engine and turn the A/C on. Set the fan to high, set the temp controls to full cold and open both windows. Put a thermometer into the center A/C vent.
At this point the gages should show pressure. The low side should be around 30 psi, and the high side around 200 psi or so.
At this point you can pierce the can by fulling closing the tapping valve. Once the can is pierced, slowly open the piercing valve, and then slowly open the BLUE valve. You are now charging refrigerant. The blue gage will show a higher pressure, and the refirgerant can will start to get cool. Let the system charge for a few seconds and then close the blue valve. Look at the low and high side pressures. If the low side is above 30 psi, remove the jumper from the low pressue switch plug (the compressor will stop), and then reconnect the plug to the low pressure switch. If the compressor starts again, let the system run and measure the air temperature at the center vent.
Raise the engine RPM to around 1200 or so and check the sight glass in the top of the reciever/dryer for bubbles and charge small amounts of refrigerant until the bubbles stop. Check you low and high side pressures. Low should be around 30 psi, and high will be around 200.
Close the windows and let the system cool the passenger compartment. Check the vent temperature and watch the compressor. When the system is operating properly the compressor will cycle on and off and maintain a vent temperature between 40 and 50 degrees.
If you get this far you can shut the car off, verify that the can-tap and blue mainfold valves are closed and disconnect the hoses. NOTE: Put a shop rag around the hose fittings to catch any refrigerant and oil.
Now take the car for a drive and check the system. Make sure the vents work properly, and that the temperature control actually controls the A/C temperature.
On the other hand if you discover that the system is leaking you will need to find the leak, fix it, evacuate the sytem, and then charge the system.
To evacuate the system you connect a gage manifold and connect a vacuum pump to the yellow charging hose. Start the pump and slowly open the red and blue valves. Let the pump run until the low side pressure indicates at least 28" Hg of vacuum. Close the red and blue valves and stop the pump. Let the system sit for about 30 minutes. If the low side pressure increases (less vacuum), start the pump and open the valves. Let the pump run for 30 minutes. Shut the valves, stop the pump and let the system sit for 30 minutes. If the vacuum drops you have a leak that must be found and fixed. If the vacuum holds you can disconnect the pump and re-charge the system.
This should give you a good idea of what you're in for, which is why most folks will recommend taking the car to a certified A/C shop.
If you need to convert the system to R-134, you need to replace the reciever/dryer, disconnect and dump the compressor (R-12 and R-134 compressor oil are NOT compatible), purge the rest of the system, install R-134 fittings, install new O-rings (cheap at NAPA), evacuate the system, and then charge new oil and refrigerant. To get the right amount of R-134 you need to look at the sticker below the coolant expansion tank. Multiply that number by .85.
Final note: If you want more detailed information, go to your local parts store and get a copy of Haynes TechBook Automotive Heating and Air Conditioning 10425 (1480) ISBN 1 56392 071 9.
HTH
No pun intended, but you need to cop a chill and do some reading.
First off you need to know how an A/C system is designed to work, what the individual components do, what refirgerant is currently in the system, and how to use a gage manifold.
If the system just needs to be topped off, then you can charge the system yourself. To do this you will need the correct refrigerant, and either a "cheap" one hose charging rig, or a set of gages. I prefer to use gages.
To charge the system using a gage manifold you connect the low pressure hose (blue) to the LOW pressure or suction side of the compressor. For your car the low side fitting should be at the rear of the compressor. The high pressure (red) hose connects to the fitting by the driver side cam tower. The yellow hose is normall connected to a refrigerant bottle, but in your case you remove the yellow hose and replace it with a "can-tap."
The can-tap is a short section of yellow hose with a piercing valve that connects to a can of refirgerant. Verify that the piercing valve is fully open (piercing pin fully retracted into the valve), and the red and blue valves are fully closed. Don't skip this step or you'll rupture a hose and ruin you day!
Next, disconnect the low presssure switch (located just forward of the reciever/dryer) and jumper the wires together. This is necessary because the low pressure switch controls the compressor.
With the low pressure wires jumpered and the hoses connected, start the engine and turn the A/C on. Set the fan to high, set the temp controls to full cold and open both windows. Put a thermometer into the center A/C vent.
At this point the gages should show pressure. The low side should be around 30 psi, and the high side around 200 psi or so.
At this point you can pierce the can by fulling closing the tapping valve. Once the can is pierced, slowly open the piercing valve, and then slowly open the BLUE valve. You are now charging refrigerant. The blue gage will show a higher pressure, and the refirgerant can will start to get cool. Let the system charge for a few seconds and then close the blue valve. Look at the low and high side pressures. If the low side is above 30 psi, remove the jumper from the low pressue switch plug (the compressor will stop), and then reconnect the plug to the low pressure switch. If the compressor starts again, let the system run and measure the air temperature at the center vent.
Raise the engine RPM to around 1200 or so and check the sight glass in the top of the reciever/dryer for bubbles and charge small amounts of refrigerant until the bubbles stop. Check you low and high side pressures. Low should be around 30 psi, and high will be around 200.
Close the windows and let the system cool the passenger compartment. Check the vent temperature and watch the compressor. When the system is operating properly the compressor will cycle on and off and maintain a vent temperature between 40 and 50 degrees.
If you get this far you can shut the car off, verify that the can-tap and blue mainfold valves are closed and disconnect the hoses. NOTE: Put a shop rag around the hose fittings to catch any refrigerant and oil.
Now take the car for a drive and check the system. Make sure the vents work properly, and that the temperature control actually controls the A/C temperature.
On the other hand if you discover that the system is leaking you will need to find the leak, fix it, evacuate the sytem, and then charge the system.
To evacuate the system you connect a gage manifold and connect a vacuum pump to the yellow charging hose. Start the pump and slowly open the red and blue valves. Let the pump run until the low side pressure indicates at least 28" Hg of vacuum. Close the red and blue valves and stop the pump. Let the system sit for about 30 minutes. If the low side pressure increases (less vacuum), start the pump and open the valves. Let the pump run for 30 minutes. Shut the valves, stop the pump and let the system sit for 30 minutes. If the vacuum drops you have a leak that must be found and fixed. If the vacuum holds you can disconnect the pump and re-charge the system.
This should give you a good idea of what you're in for, which is why most folks will recommend taking the car to a certified A/C shop.
If you need to convert the system to R-134, you need to replace the reciever/dryer, disconnect and dump the compressor (R-12 and R-134 compressor oil are NOT compatible), purge the rest of the system, install R-134 fittings, install new O-rings (cheap at NAPA), evacuate the system, and then charge new oil and refrigerant. To get the right amount of R-134 you need to look at the sticker below the coolant expansion tank. Multiply that number by .85.
Final note: If you want more detailed information, go to your local parts store and get a copy of Haynes TechBook Automotive Heating and Air Conditioning 10425 (1480) ISBN 1 56392 071 9.
HTH
05-23-2004, 04:32 PM
#21
Lazer Beam Shooter
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I dont see any blue or red hoses here. What i do see are the two Valve stem things that look like tire valve stems. Am i doing something wrong here?
05-23-2004, 05:15 PM
#23
Three Wheelin'
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But by that logic, whenever they re-charge a system they have to fix a leak.
I could be wrong, but I think it is illegal to vent R12 into the atmosphere or charge a system that will leak R12 into the atmoshpere. I think this is part of the Clean Air Act called the SNAP Rule.
05-23-2004, 05:17 PM
#24
Three Wheelin'
The "tire valve stems" are the service port fittings. If one is not near the compressor, then the smaller diameter line is the high pressure (red) side, and the larger diameter line is the low pressure (blue) line.
On my '87 NA the high side fitting is near the driver side shock tower, and the low side fitting is at the rear of the compressor. On my '86 951 both fittings are near the shock tower, with the high pressure line being outboard of the low pressure line. Here again, the low side line is the larger of the two.
BTW: The pic of the gage manifold is for R-12/R-22 systems.
On my '87 NA the high side fitting is near the driver side shock tower, and the low side fitting is at the rear of the compressor. On my '86 951 both fittings are near the shock tower, with the high pressure line being outboard of the low pressure line. Here again, the low side line is the larger of the two.
BTW: The pic of the gage manifold is for R-12/R-22 systems.
05-23-2004, 06:32 PM
#25
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Well, I just had them charge it with R12 - yes it was expensive as all getout, but worth it as I now have achieved the desired result: I have nice cold air that I wouldn't think twice about going to Phoenix in August with. The Ian's kit does NOT come with r134a fittings for everyone's info. I double and triple-checked this. I even called 944Online and they just said to get the adapters if I needed them, the compressor could go either way.
I opted for the r12 mostly due to the fact that's what the original system was designed for - the condenser and evaporator are sized for r12 based results, not r134. Not to say that r134 wouldn't work and hasn't been made to work well with some systems, but if the system is now 100% leakproof, why do I care about being able to "top it off" myself? I shouldn't have to. Plus this shop uses pure r12, not the knock-off stuff, so I know what's in there should I ever need to bring it in for a top-off.
I opted for the r12 mostly due to the fact that's what the original system was designed for - the condenser and evaporator are sized for r12 based results, not r134. Not to say that r134 wouldn't work and hasn't been made to work well with some systems, but if the system is now 100% leakproof, why do I care about being able to "top it off" myself? I shouldn't have to. Plus this shop uses pure r12, not the knock-off stuff, so I know what's in there should I ever need to bring it in for a top-off.
05-23-2004, 07:49 PM
#26
Three Wheelin'
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Great P-O-P, the ac will be good for another 19 years. 
Brad-cam, I'm no expert, but I've read somewhere that its normal for systems to lose about 3 ounces of R12 a year.
Brad-cam, I'm no expert, but I've read somewhere that its normal for systems to lose about 3 ounces of R12 a year.
05-23-2004, 10:59 PM
#27
Instructor
I don't know why everyone makes a big deal about the "conversion kit". The only thing that is different is you add a low side valve and high side valve, and they'll cost maybe $10 for both at Pep boys. Vacuum it down, put some oil in, and around 38oz of r134a and you good to go. Years ago I had r12 put in it for around $300. A week later the compressor broke. So now I work on cars and "convert" them all the time. My car now has a new compressor with r134a and the other day I checked the temp. and it was blowing 42 degrees. Good enough for me.
Just don't be fooled when people act like a conversion is a big deal...it's not. But the way people make it seem is like your getting all new parts and this and that. Sure the r134a runs at a higher pressure, but the system was designed to have pressure it it anyways...nothings going to break. I'll never waste money on R12 again. And by the way, walmart sells the kit for $35. enjoy the hot weather.
Just don't be fooled when people act like a conversion is a big deal...it's not. But the way people make it seem is like your getting all new parts and this and that. Sure the r134a runs at a higher pressure, but the system was designed to have pressure it it anyways...nothings going to break. I'll never waste money on R12 again. And by the way, walmart sells the kit for $35. enjoy the hot weather.
05-23-2004, 11:16 PM
#28
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Years ago, I bought R12 for $2 a can at Kmart. Wish I'd bought several cases then.
Anyway, Mikec944, don't you at least change out the drier when you do the conversions?
Anyway, Mikec944, don't you at least change out the drier when you do the conversions?
05-23-2004, 11:54 PM
#30
Instructor
I didn't opt for that but it is a good idea since it is the filter of the system. All hell is not going to break loose if it isn't changed. Not much to change it anyway.