When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
On FB marketplace people sell the 12 oz cans for about $20. A can of r134 costs close to that. People sell used 30 lb bottles between $20-$300. Right now there’s a 30 lb of r12 in San Diego for $250 advertised as 100% full.
I think you might be a bit confused on your claims. I cross the border into North Dakota on a regular basis and can buy R134A from Walmart for 9.98 any day of the week. Last fall I hit a sale at Tractor Supply and it was 6.98 for a 12 oz. can. (substantially lower than your "about" 20.) It would be helpful for you to post a link to some of the "Marketplace hot deals of the week" - especially the 30 lb cylinder for 250. If it is indeed true, the seller is an idiot or it's stolen. A quick Google search on different forums tells me 12 oz. cans of R12 are commanding $55 and up - if you can find one.
*NEVER MIND THE LINK - It came to me that this was another case of someone not understanding refrigerants. I found it on San Diego Marketplace and that IS NOT R12!!! It is Freeze 12 which is a blend of R134A and R142B. It has absolutely zero R12 in it. It says right on the tank "No CFC's" which is the designation of R12. This happens quite often in the automotive stores as different variants of this are sold with catchy names that resemble "R12" (or R134A) but if you take a look at the microscopic print at the bottom, they all say "R12 replacement"
On FB marketplace people sell the 12 oz cans for about $20. A can of r134 costs close to that. People sell used 30 lb bottles between $20-$300. Right now there’s a 30 lb of r12 in San Diego for $250 advertised as 100% full.
The problem is I live in the middle of know where Texas. I can’t get stuff that easily just because FB marketplace and Craigslist are none existent or you gotta drive 4+ hours.
OP, your best bet will probably be to convert to R134. I've been able to find real R12 on FB Marketplace in my area, but at the end of the day R134 is much cheaper and readily available at any auto parts store. Even Walmart like mentioned above.
Ok, so I got the gauges in the mail. I was not able to thread on to what I assume to be the high side. It was the smaller line on the bottom. It might need some sort of adapter I do not have for those threads.
However I was able to thread on to the Filter Drier Accumulator. It had 130 PSI with the car running and off.
The compressor never seems to turn no matter what I try. I have tried unplugging it and replugging it in while the car is running. When I unplug it the car changes idle little bit. And when I plug it in it changes a little bit also. But the compressor never turns. I can turn it with my hand while the car is off and I do hear it moving stuff around when I do that.
Update, I checked power to the compressor. It was getting power. I then Bypassed whis switch (I don't know what switch this is) and the compressor turned! I also got cold air inside.
SO if this is the problem do I just need to replace the switch? Or does it mean something else. Also No I didnt let it run for more than a minute with me bypassing the switch.
Update, I checked power to the compressor. It was getting power. I then Bypassed whis switch (I don't know what switch this is) and the compressor turned! I also got cold air inside.
SO if this is the problem do I just need to replace the switch? Or does it mean something else. Also No I didnt let it run for more than a minute with me bypassing the switch.
You can test the switch by using a volt meter and putting it across the points on the switch in the continuity mode see if it's open (odds are it is, either low pressure or failure) Start the car and do your jump again on plug side to recreate the compressor to run, and see what the switch does. Also see what the pressures are in that brief run to confirm whether gas is below operation.
I believe that is the low pressure switch so I think they go open on low and and are closed under proper pressure
Last edited by s carter; Mar 14, 2025 at 08:14 PM.
Update, I checked power to the compressor. It was getting power. I then Bypassed whis switch (I don't know what switch this is) and the compressor turned! I also got cold air inside.
SO if this is the problem do I just need to replace the switch? Or does it mean something else. Also No I didnt let it run for more than a minute with me bypassing the switch.
Hi have attached pics of my shop manual, if you have the electronic a/c as in the image a fault will cause the green indicator to flash. You will need to reset the fault like low freon, to enable the air-conditioning to operate. The images should help you, that low pressure switch is used to cycle the compressor and act as a safety to prevent damage in case of low freon. Am pretty sure there is a Schrader valve in the fitting its screwed onto, so it can be replaced easily without loosing freon. Just turn it half a turn to one turn anticlockwise and you will hear a short hiss then stop. Then you can remove and replace if its faulty. Should open below 22psi and close again when pressure back over 40 psi, so is used as a combination clutch control and low refrigerant safety. The electronics will determine failure by flashing the climate control green led indicator if it detects a fault. Refer to images how to check codes and reset 🙂👍
Update, I checked power to the compressor. It was getting power. I then Bypassed whis switch (I don't know what switch this is) and the compressor turned! I also got cold air inside.
SO if this is the problem do I just need to replace the switch? Or does it mean something else. Also No I didnt let it run for more than a minute with me bypassing the switch.
Sorry, again, but you have no clue what you are doing. You bought a set of gauges but you have "no codes" so you have no indication of low Freon in the system. If you indeed have low Freon and no codes, then you have a more major problem. Are you sure you know how to read codes? And if the Freon level is low there would be a green blinking light on as soon as you turn the system on, and then an 09 code when you interrogate it. You measure a highside pressure with the engine running and the engine off but the compressor will not turn on? That is totally meaningless. And FYI, if there was a code 09 indicating low Freon, the compressor will NOT run without bypassing it until the code is cleared and that is done by disconnecting the battery for 30 sec. or more and then turning it on to try again. You also cannot refill the system or add Freon unless the compressor is running, and that may mean bypassing the low pressure switch to engage the compressor and then once it's filled enough, removing the bypass and reconnecting the switch and filling it up all the way.
Before wasting more time and money, take it to an AC repair shop and have them look at it as it seems this is out of your expertise and you are getting a lot of useless advice.
Sorry, again, but you have no clue what you are doing. You bought a set of gauges but you have "no codes" so you have no indication of low Freon in the system. If you indeed have low Freon and no codes, then you have a more major problem. Are you sure you know how to read codes? And if the Freon level is low there would be a green blinking light on as soon as you turn the system on, and then an 09 code when you interrogate it. You measure a highside pressure with the engine running and the engine off but the compressor will not turn on? That is totally meaningless. And FYI, if there was a code 09 indicating low Freon, the compressor will NOT run without bypassing it until the code is cleared and that is done by disconnecting the battery for 30 sec. or more and then turning it on to try again. You also cannot refill the system or add Freon unless the compressor is running, and that may mean bypassing the low pressure switch to engage the compressor and then once it's filled enough, removing the bypass and reconnecting the switch and filling it up all the way.
Before wasting more time and money, take it to an AC repair shop and have them look at it as it seems this is out of your expertise and you are getting a lot of useless advice.
why do you keep saying I have no clue what I am doing?
I bought the gauges high side pressure was 130psi.
I got the compressor to run by bypassing the low Freon sensor.
yes if you read the above comment . He sent me pictures of how to check the AC for codes. I did check it by holding the up and down fan speed buttons. It says -00 then I hit auto and it still says 00.
So all I was commenting was no there is no 09 code or trouble codes on the AC.
I also found where it is leaking today. So I will repair it.
not sure why so much negativity in this thread about ACs. Just trying to learn more about them. But chanting TAKE IT TO THE SHOP every other comment is not helping.
why do you keep saying I have no clue what I am doing?
I bought the gauges high side pressure was 130psi.
I got the compressor to run by bypassing the low Freon sensor.
yes if you read the above comment . He sent me pictures of how to check the AC for codes. I did check it by holding the up and down fan speed buttons. It says -00 then I hit auto and it still says 00.
So all I was commenting was no there is no 09 code or trouble codes on the AC.
I also found where it is leaking today. So I will repair it.
not sure why so much negativity in this thread about ACs. Just trying to learn more about them. But chanting TAKE IT TO THE SHOP every other comment is not helping.
OK, let's take this one step at a time. First of all, no offense intended, but you DON'T know what you are doing. I will try to help you but AC work is not something you learn over a chat forum. The first thing I would suggest is go on Youtube and learn about the refrigeration cycle. Then you will understand how things operate. I will point out that some of the things you say is what makes people here question you. A few posts back, you said you couldn't hook up to the high side. You said you needed a fitting. Your last post said you hooked up to the HIGH SIDE and it was 130. Which way is it? Previously, you said the compressor wasn't turning but the pressure was 130. IMPOSSIBLE unless the ambient temperature where you are is over 100° F. I don't know about blinking lights and codes here but I DO know AC. Been doing it for over 30 years. Many things to learn before you dive in with both feet to unfamiliar territory. Do some reading and research first. You have to know where to hook up, how to add refrigerant safely and not introduce non-condensables and do all this without injuring yourself. Are you wearing gloves and goggles? Remove one wrong component and get a shot of liquid freon in your eyes and it's game over for that eye. Everyone here will help you along but you got to learn the basics first.
OK, let's take this one step at a time. First of all, no offense intended, but you DON'T know what you are doing. I will try to help you but AC work is not something you learn over a chat forum. The first thing I would suggest is go on Youtube and learn about the refrigeration cycle. Then you will understand how things operate. I will point out that some of the things you say is what makes people here question you. A few posts back, you said you couldn't hook up to the high side. You said you needed a fitting. Your last post said you hooked up to the HIGH SIDE and it was 130. Which way is it? Previously, you said the compressor wasn't turning but the pressure was 130. IMPOSSIBLE unless the ambient temperature where you are is over 100° F. I don't know about blinking lights and codes here but I DO know AC. Been doing it for over 30 years. Many things to learn before you dive in with both feet to unfamiliar territory. Do some reading and research first. You have to know where to hook up, how to add refrigerant safely and not introduce non-condensables and do all this without injuring yourself. Are you wearing gloves and goggles? Remove one wrong component and get a shot of liquid freon in your eyes and it's game over for that eye. Everyone here will help you along but you got to learn the basics first.
got it thanks. When I checked, it was 101 degrees outside. I live in Texas super hot.
I hooked up one gauge to the dryer, is that not the high side? There’s only two fittings I can hook up to one on the dryer and one on a skinnier line. The skinnier line on the bottom is the one I could not hook up to because I need a fitting.
the leak I found was when I by passed the sensor. There is a bigger line that threads on to another line by the firewall. I heard hissing when the compressor was running from where it threads on.
I have been watching YouTube videos and reading. But the C4 system seems a little bit different than newer systems.
got it thanks. When I checked, it was 101 degrees outside. I live in Texas super hot.
I hooked up one gage to the dryer accumulator is that not the high side? There’s only two fittings I can hook up to one on the dryer and one on a skinnier line. The skinnier line on the bottom is the one I could not hook up to because I need a fitting. I have been watching YouTube videos and reading. But the C4 system seems a little bit different than newer systems.
No, the accumulator is the low side. The small line is the high liquid line. R12 at 100° F should be about 117 or so. If you had just driven it, the ambient under the hood was probably higher meaning your 130 is within reason. The only major thing between a C4 and newer vehicles is that the C4 uses an orifice tube to lower the pressure and most new vehicles use an "H" block TXV. However, the cycle is the same for both - evaporate, compress, condense, lower the pressure. Orifice tubes use an accumulator and TXV's use a receiver. They both generally have desiccant to remove moisture.
If you have no blinking green light and no codes (00) then you have no low Freon pressure. Or, your computer system/sensor is FUBAR, and, like I said, you have a bigger problem. You are checking for leaks when your car says you don't have one. Noise or hissing may not indicate a leak by itself. Do you feel or see a rush of gas? If you really want to test for or find a leak you use a sniffer or a fluorescent dye. And how are you going to repair your leak?
By the way, have you checked your fuses?
Have a good day, I hope you solve your problem. I'm done here.
Update, I checked power to the compressor. It was getting power. I then Bypassed whis switch (I don't know what switch this is) and the compressor turned! I also got cold air inside.
SO if this is the problem do I just need to replace the switch? Or does it mean something else. Also No I didnt let it run for more than a minute with me bypassing the switch.
You bypassed the Low Pressure Switch. If you bypassed the switch, and you’re getting cold air, then the switch is bad. Very easy to replace, there is a Shrader valve underneath the low pressure switch, so when you “unscrew” the old switch no refrigerant will excape. Just screw the new switch in, very easy. You might get a very small noise of pressure when you remove/replace it, but if you do it fast enough it won’t be a problem. (I’ve been ASE certified and have been working on automotive AC for over 30 years)
If you get cold air inside the car, then the system is working, you can leave the switch bypassed until you get a new one as long as you have cold air. The chances of you getting a leak between now and when you get a new switch is pretty rare.
You bypassed the Low Pressure Switch. If you bypassed the switch, and you’re getting cold air, then the switch is bad. Very easy to replace, there is a Shrader valve underneath the low pressure switch, so when you “unscrew” the old switch no refrigerant will excape. Just screw the new switch in, very easy. You might get a very small noise of pressure when you remove/replace it, but if you do it fast enough it won’t be a problem. (I’ve been ASE certified and have been working on automotive AC for over 30 years)
If you get cold air inside the car, then the system is working, you can leave the switch bypassed until you get a new one as long as you have cold air. The chances of you getting a leak between now and when you get a new switch is pretty rare.
^^^^ Wrong. If you take the cycling switch out of the equation for any length of time, you will freeze the evaporator. Why is it there if it is ok to bypass it???
