A/C system recharge DIY

[tony-muscle]

Two years ago when I removed my engine I emptied the refrigerant from my A/C system so it has been empty for about 1.5 years. Now it is time to recharge. I have a set of A/C gauges and a vacuum pump that I rented from Autozone. From what I understand I need to vacuum the system, vacuum test for some time, charge oil??, charge system with refrigerant, etc I already have the refrigerant bottles. My system as already R134a. I am looking for general instructions on how to proceed. Questions that I have: vacuum level, vacuum test time, amount of oil to add, amount of refrigerant to add or pressure. Any guidance is appreciated.

 

[vintageman]

Tony-Muscle, someone with experience with our cars will probably chime in but I worked on a system last year for my neighbor that had been open for about a year, he had left his lines open the whole time and we had to change his dryer bottle and all of the O rings at the connections. Your system should have High and Low sensors on them as well, I would do a test on them to make sure that they are good. Other than that, I pulled a vacuum on the system for about 45 minutes if I remember correctly. The gauges will tell you if you are holding vacuum or not. Can't really remember a lot on the filling part, but the directions that came with the gauges should tell you to watch either the High or Low gauge. I think for a full system, we used about 2 or 3 of the bigger cans of freon. There is also freon that has dye in it that I recommend that you use, after you fill the system, run it for a while, then the next day or so, take a black light (my age shows there) or there is a special pen light that you can buy from the AP store that you can shine on each of the connections and see if there is a leak. Good luck, hopefully some of this was of help.

Tom

 

[Don C]

There's likely some oil still in the compressor. Does the new refrigerant have oil in it? If so that and what's still in the compressor should be enough. Otherwise I would add a small amount 1/2 ounce, or so.

You'll need to run the vacuum pump for a half hour or so, you'll be looking for 28+ inches of vacuum. 15 to 30 minutes should be enough time to tell if you have a leak, or not. I would add a can of leak stop while you're at it, should help recondition the seals. Depending on the size of the cans of refrigerant, it'll probably take 3 cans. You'll be able to tell by watching the gauges while you add it when you have enough in it. The gauges should show the range of acceptable pressures for both the low and high sides.

Make sure you lubricate the o-rings before hooking everything up.

 

[tony-muscle]

Thanks. I found this chart for the pressure range to fill the system:

R-134a TEMPERATURE PRESSURE CHART (http://rechargeac.com/how-to/ac-system-pressure-chart)

Ambient

Temperature °F / °C Low-Pressure Gauge High-Pressure Gauge

65°F (18°C) 25-35 psi / 172-241 kPa 135-155 psi / 931-1069 kPa

70°F (21°C) 35-40 psi / 241-276 kPa 145-160 psi / 1000-1103 kPa

75°F (24°C) 35-40 psi / 241-310 kPa 150-170 psi / 1034-1172 kPa

80°F (27°C) 40-50 psi / 276-345 kPa 175-210 psi / 1207-1448 kPa

85°F (29°C) 45-55 psi / 310-379 kPa 225-250 psi / 1551-1724 kPa

90°F (32°C) 45-55 psi / 310-379 kPa 250-270 psi / 1724-1862 kPa

95°F (35°C) 50-55 psi / 345-379 kPa 275-300 psi / 1896-2068 kPa

100°F (38°C) 50-55 psi / 345-379 kPa 315-325 psi / 2172-2241 kPa

105°F (41°C) 50-55 psi / 345-379 kPa 330-335 psi / 2275-2310 kPa

110°F (43°C) 50-55 psi / 345-379 kPa 340-345 psi / 2344-2379 kPa

PS: sorry, a bit hard to read in text format.

 

[tony-muscle]

There's likely some oil still in the compressor. Does the new refrigerant have oil in it? If so that and what's still in the compressor should be enough. Otherwise I would add a small amount 1/2 ounce, or so.

You'll need to run the vacuum pump for a half hour or so, you'll be looking for 28+ inches of vacuum. 15 to 30 minutes should be enough time to tell if you have a leak, or not. I would add a can of leak stop while you're at it, should help recondition the seals. Depending on the size of the cans of refrigerant, it'll probably take 3 cans. You'll be able to tell by watching the gauges while you add it when you have enough in it. The gauges should show the range of acceptable pressures for both the low and high sides.

Make sure you lubricate the o-rings before hooking everything up.

The new refrigerant is "pure" with no oil so I think I need to add a little bit of oil. I kept the system closed all this time to reduce the chances of refrigeration.

Thanks for the tip in lubricating the o-rings. I didn't do that so I will redo some o-rings that are easy to reach before recharging. The two connections by the firewall are nearly impossible to get to due to my electric gas sump pump being in the area. I read to use Nylog type of lubricant for the o-rings.

 

[Carolina_Mountain_Mustangs]

I can get you a scanned copy of the Ford service manual if you want. It gives the level of oil needed in the compressor. There are to drain plugs on the compressor if it is original and both have O-rings on the but there is not refrigerant in there. There is also an O-ring on the vent that may need attention.

I have done a couple of them for sure not rocket science. I always clean the O-ring surfaces with fine steel wool. If there is rust inside the metal ends of the lines I clean with wire rifle cleaning brushes then wash out thoroughly. If you do not have anything to lube the O-rings with Mineral Oil will work fine.

I am very happy with the DuraCool 12a refrigerant that I use from Canada. It takes much less. A system will actually cool pretty good with just one can of their refrigerant and I also use their lube in the compressor. They say the molecule size in their refrigerant is larger so you have less chance of a leak. They will ship right to your door no issue. Here is link. http://www.duracool.com/Duracool/refrigerants.html

I believe I would change the oil in the compressor.

If there is signs of oil around the clutch then the seal is leaking. It is a pretty fancy little seal in there. I put one in the Mach 1 last month was not difficult and found it on ebay was NOS Ford.

I had not got the vacuum lines all back on my 73 vert but was going to do that today and will see if mine still works, lol. It is in the 90's here now so need air in a vert for sure.

 

[tony-muscle]

I can get you a scanned copy of the Ford service manual if you want. It gives the level of oil needed in the compressor. There are to drain plugs on the compressor if it is original and both have O-rings on the but there is not refrigerant in there. There is also an O-ring on the vent that may need attention.

I have done a couple of them for sure not rocket science. I always clean the O-ring surfaces with fine steel wool. If there is rust inside the metal ends of the lines I clean with wire rifle cleaning brushes then wash out thoroughly. If you do not have anything to lube the O-rings with Mineral Oil will work fine.

I am very happy with the DuraCool 12a refrigerant that I use from Canada. It takes much less. A system will actually cool pretty good with just one can of their refrigerant and I also use their lube in the compressor. They say the molecule size in their refrigerant is larger so you have less chance of a leak. They will ship right to your door no issue. Here is link. http://www.duracool.com/Duracool/refrigerants.html

I believe I would change the oil in the compressor.

If there is signs of oil around the clutch then the seal is leaking. It is a pretty fancy little seal in there. I put one in the Mach 1 last month was not difficult and found it on ebay was NOS Ford.

I had not got the vacuum lines all back on my 73 vert but was going to do that today and will see if mine still works, lol. It is in the 90's here now so need air in a vert for sure.

Be looking at the old receipts, the previous owner got a new York compressor in 2003 from NPD. The compressor was then rebuilt in 2013. At that time they replaced the oil. There are no signs of leakage anywhere in the system so I think I will just add a little bit more of oil per Dan's recommendation and move on.

 

[turtle5353]

Don't forget to have the car running and AC on while you are filling it so the pump cycles on and off to help pull in the refrigerant. I also found that holding the can upside down helps too. I just recharged the Yellow Mach 1 I was working on and if I remember correctly it took 3 cans.

 

[tony-muscle]

I have a question. When you pull and hold vacuum in the system, does the oil come out or does it stay?

Also, do you start filling the system while you are holding the vacuum?

Sent from my SAMSUNG-SM-G930A using Tapatalk

 

[Carolina_Mountain_Mustangs]

I can get you a scanned copy of the Ford service manual if you want. It gives the level of oil needed in the compressor. There are to drain plugs on the compressor if it is original and both have O-rings on the but there is not refrigerant in there. There is also an O-ring on the vent that may need attention.

I have done a couple of them for sure not rocket science. I always clean the O-ring surfaces with fine steel wool. If there is rust inside the metal ends of the lines I clean with wire rifle cleaning brushes then wash out thoroughly. If you do not have anything to lube the O-rings with Mineral Oil will work fine.

I am very happy with the DuraCool 12a refrigerant that I use from Canada. It takes much less. A system will actually cool pretty good with just one can of their refrigerant and I also use their lube in the compressor. They say the molecule size in their refrigerant is larger so you have less chance of a leak. They will ship right to your door no issue. Here is link. http://www.duracool.com/Duracool/refrigerants.html

I believe I would change the oil in the compressor.

If there is signs of oil around the clutch then the seal is leaking. It is a pretty fancy little seal in there. I put one in the Mach 1 last month was not difficult and found it on ebay was NOS Ford.

I had not got the vacuum lines all back on my 73 vert but was going to do that today and will see if mine still works, lol. It is in the 90's here now so need air in a vert for sure.

Be looking at the old receipts, the previous owner got a new York compressor in 2003 from NPD. The compressor was then rebuilt in 2013. At that time they replaced the oil. There are no signs of leakage anywhere in the system so I think I will just add a little bit more of oil per Dan's recommendation and move on.

You should actually check the level and not overfill it. Just like your engine bad to have too much oil in there. In another post there was info on the fill level I believe.

 

[tony-muscle]

I can get you a scanned copy of the Ford service manual if you want. It gives the level of oil needed in the compressor. There are to drain plugs on the compressor if it is original and both have O-rings on the but there is not refrigerant in there. There is also an O-ring on the vent that may need attention.

I have done a couple of them for sure not rocket science. I always clean the O-ring surfaces with fine steel wool. If there is rust inside the metal ends of the lines I clean with wire rifle cleaning brushes then wash out thoroughly. If you do not have anything to lube the O-rings with Mineral Oil will work fine.

I am very happy with the DuraCool 12a refrigerant that I use from Canada. It takes much less. A system will actually cool pretty good with just one can of their refrigerant and I also use their lube in the compressor. They say the molecule size in their refrigerant is larger so you have less chance of a leak. They will ship right to your door no issue. Here is link. http://www.duracool.com/Duracool/refrigerants.html

I believe I would change the oil in the compressor.

If there is signs of oil around the clutch then the seal is leaking. It is a pretty fancy little seal in there. I put one in the Mach 1 last month was not difficult and found it on ebay was NOS Ford.

I had not got the vacuum lines all back on my 73 vert but was going to do that today and will see if mine still works, lol. It is in the 90's here now so need air in a vert for sure.

Be looking at the old receipts, the previous owner got a new York compressor in 2003 from NPD. The compressor was then rebuilt in 2013. At that time they replaced the oil. There are no signs of leakage anywhere in the system so I think I will just add a little bit more of oil per Dan's recommendation and move on.

You should actually check the level and not overfill it. Just like your engine bad to have too much oil in there. In another post there was info on the fill level I believe.

David. I forgot that I have the shop manual.  In 36-30-09 it talks about a procedure to check the oil level. However, I don't have a way to isolate the compressor as explained there. I assume that the oil level would be similar when the system is not charged. I feel more confortable measuring the oil level with the system uncharged.

 

[Carolina_Mountain_Mustangs]

Ok maybe I am crazy. The refrigerant is only on the head side of the compressor. The crankcase where the oil is would be just like your air compressor with no gas there. There is actually a vent on the crankcase about 3/4" dia. and maybe 1 1/2" long.

You should be able to take the plug out of the top and put wire in to check the oil level.

You also ask if the vacuum pulled the oil out and the answer is no. If it did then you have bad rings on the pistons and would not hold a vacuum due to the vent.

When I did mine I pulled a vacuum and turned it off and went and ate lunch came back and it did not drop so should have been a good sealed system.

I still have not got mine back in to check it and fix vacuum lines.

I intend to drive it to Charlotte to the MOM at the end of the month and AC would be great with it getting into the 90's here.

I cannot believe how much difference the Lucas gas treatment makes in the operating temp of the engine.

I am still thinking I will be a separate transmission cooler on to get that heat out of the radiator. Especially when running the AC.

 

[tony-muscle]

Ok maybe I am crazy. The refrigerant is only on the head side of the compressor. The crankcase where the oil is would be just like your air compressor with no gas there. There is actually a vent on the crankcase about 3/4" dia. and maybe 1 1/2" long.

You should be able to take the plug out of the top and put wire in to check the oil level.

You also ask if the vacuum pulled the oil out and the answer is no. If it did then you have bad rings on the pistons and would not hold a vacuum due to the vent.

When I did mine I pulled a vacuum and turned it off and went and ate lunch came back and it did not drop so should have been a good sealed system.

I still have not got mine back in to check it and fix vacuum lines.

I intend to drive it to Charlotte to the MOM at the end of the month and AC would be great with it getting into the 90's here.

I cannot believe how much difference the Lucas gas treatment makes in the operating temp of the engine.

I am still thinking I will be a separate transmission cooler on to get that heat out of the radiator. Especially when running the AC.

Maybe I am the one confused because I have not dealt with A/C before. The reason I say that is because the manual states that you should "isolate" the compressor before removing the oil plug. Also, is this oil level we are talking on the compressor the same oil that is added with the refrigerant?

 

[Carolina_Mountain_Mustangs]

I am going to have to go read the Ford manual again, lol.

When I did mine I poured the container of oil into the compressor housing where the crankshaft is. I did not put any oil in with the gauges.

Now I do have old cans of R-12 that I sell and also a few cans of what they call "Air Conditioner Oil Charge & Conditioner". It says is has 2 ounces of 525 ViS high grade compressor refrigerant oil in automotive AC systems without dischargine entire system.

I do not see how much oil could be on the head side of the compressor. Oil would be tough to compress not like the gas.

I will read for sure going to rain today been dry. Going to get 6-7 inches they say so no outside work.

 

[jowens1126]

typically, all of the oil is initially put into the compressor on a system that has been flushed free of all previous oil or all components are new. That is where it is needed anyway. So once its charged and running, the oil will end up where ever it wants to be. The only time you should put oil into a specific component is when you have a fully charged system and are changing out a component like a condenser or a dryer. Then you put the appropriate amount of oil into that component and re-install it, pull vacuum and charge.

I would suggest that you should flush the system if it has been sitting for years unused or has been open to the atmosphere or you are converting to 134a or another refrigerant. Appropriate flushing solvent and solvent flushing guns are available at any parts store.

 

[Carolina_Mountain_Mustangs]

I did go back and read the manual for I think the 6th. time. No memory cells left in there. Yes the gas is in the crankcase of the compressor. So you would need to bleed off any pressure before opening the plug and then vacuum it before charging.

I got my car in the garage just before the rain started. The charge I put in two years ago is gone and I could not get my black lite to work to see if I could see stains from the leak. I am not sure if sniffer I have will find the Duracool since it is totally different.

I will get black light working tomorrow. I about bet it is the seal behind the magnetic pulley.

No need to recharge until I find the leak.

So no shows this weekend we are due to get several inches of rain.

Hope all our members in the flooded areas are safe.

 

[tony-muscle]

It was an adventure taking care of charging the A/C today. Last night I filled the compressor with oil per the instructions to about 1". Then I thought I had evacuated and vacuum tested the system and then proceeded to charge it today. However, when I open the valve to allow refrigerant into the system I noticed something was not right. The LP gauge was at 90 and the HP gauge was below zero. Eventually I figured out that something was wrong with the port valves. NO ONE HAS MENTIONED IT, but my LP port has a service valve that has to be turned to the middle for any type of service. It took a lot of head scratching until I found this article: https://www.classicautoair.com/turn-of-the-screw-adjusting-tecumseh-or-york-compressor-service-valves-on-your-cars-ac/

Apparently, this service valves in the ports existed in the older compressors, but not in the new ones so when you research A/C system charging instruction they never tell you about them. That said, the evacuation and vacuum I did the night before were useless because they were pretty much of the gauge hoses. After I figured out the service valve I evacuated the system again with the vacuum pump for 30 minutes. Then tested for 15 minutes and it held vacuum at 28. I proceeded to fill up. I filled up with about 1 1/2 cans and I reached about 210 psi in HP and 20 psi in the LP. I am a little confused on how much pressure to fill up the system with. The table that I saw for R-134 indicates about 210 psi at 80F, which was the temperature this afternoon. However, I seems that 1 1/2 can would be too little. Thoughts? Do I need to continue filling it up.

 

[kcmash]

You need to see what the LP side is to answer that.  If the HP is at the recommended pressure and you are blowing 40 degree air at the dash you are good.

If you overcharge the system you will not get sufficient pressure drop through the orifice and you will not chill well.  You could lock the system up too.

If you do not have enough in there you will get cycling of the cooling as the compressor gets starved by the lack of freon on the low side and cannot keep pressure on the high side.  So you would see a fluctuation in the HP reading and probably not cool very well.

What size cans did you use?  Does classic auto air have a chart showing how many ounces to put in?  If you were using the big 24 ounce cans, remember 1.5 cans will be 36 ounces, the same as 3 small cans.

kcmash

 

[tony-muscle]

You need to see what the LP side is to answer that.  If the HP is at the recommended pressure and you are blowing 40 degree air at the dash you are good.

If you overcharge the system you will not get sufficient pressure drop through the orifice and you will not chill well.  You could lock the system up too.

If you do not have enough in there you will get cycling of the cooling as the compressor gets starved by the lack of freon on the low side and cannot keep pressure on the high side.  So you would see a fluctuation in the HP reading and probably not cool very well.

What size cans did you use?  Does classic auto air have a chart showing how many ounces to put in?  If you were using the big 24 ounce cans, remember 1.5 cans will be 36 ounces, the same as 3 small cans.

kcmash

The LP was about 20 psi and the cans were 12 oz each.

Edit PS: the air was coming out cold. I will probably know tomorrow if it is really cold since it will be hot out.