A/C Recharge
#1
#6
Oh wow thats not very far at all from my parents house.
Dude you can get recharge kits for under 20 bucks. But if you needed a fresh charge you would have to make sure the kit had the proper oil for your compressor.
Dude you can get recharge kits for under 20 bucks. But if you needed a fresh charge you would have to make sure the kit had the proper oil for your compressor.
#7
#11
You need the gauge to get the correct charge, automotive A/C doesn't use receivers anymore, they use a critical charge. Too little or too much freon and it looses performance. Yes, more is not automatically better because too much freon raises the pressure on the low side, resulting in a higher air temp on the downstream side of the evaporator than if it had the correct charge.
On Edit:
Five mistakes in that video:
a) He should have purged the air out of the line between the R-134 bottle and the system. Air does not condense, refrigerant does.
b) Engine speed should have been maintained around 1200 - 1500 rpm while charging, thus evaluating system pressures to the normal working level.
c) Fan speed should have been on high with windows open.
d) No gauges were used to determine how much refrigerant was needed. Fail. He may need more, he may have overcharged it. No gauges = hope for the better or maybe get lucky. The system holds something like 2 1/2 or 3 pounds and the can in his hand holds 14oz. He put in a lot, blindly.
e) When the can is dispensing refrigerant, it's dispensing liquid with the valve pointed down and gas with the valve pointed up. He's feeding refrigerant into the low side which is low pressure gas (which is the correct side), but administering liquid (as he did) on a cool day, and/or at a rapid rate comes with the risk of the liquid entering the compressor (slugging) and, well, the liquid won't compress. Nearly always the liquid will boil before hitting the compressor but you have to watch it and be aware. Good service procedure would dictate being in a position to very quickly disable the compressor if you started slugging it with liquid.
f) Best time to charge a system is when the outside temp is at least 70*, and actually 80*+ is better. Makes it easier to get the charge, based on pressure, correct.
*It's smart to wear goggles when charging a system; get a stream of liquid refrigerant in your eye and you can freeze your eyeball and lose an eye. They don't grow back. Just a few observations from the vid that readers here will hopefully find useful.
On Edit:
Five mistakes in that video:
a) He should have purged the air out of the line between the R-134 bottle and the system. Air does not condense, refrigerant does.
b) Engine speed should have been maintained around 1200 - 1500 rpm while charging, thus evaluating system pressures to the normal working level.
c) Fan speed should have been on high with windows open.
d) No gauges were used to determine how much refrigerant was needed. Fail. He may need more, he may have overcharged it. No gauges = hope for the better or maybe get lucky. The system holds something like 2 1/2 or 3 pounds and the can in his hand holds 14oz. He put in a lot, blindly.
e) When the can is dispensing refrigerant, it's dispensing liquid with the valve pointed down and gas with the valve pointed up. He's feeding refrigerant into the low side which is low pressure gas (which is the correct side), but administering liquid (as he did) on a cool day, and/or at a rapid rate comes with the risk of the liquid entering the compressor (slugging) and, well, the liquid won't compress. Nearly always the liquid will boil before hitting the compressor but you have to watch it and be aware. Good service procedure would dictate being in a position to very quickly disable the compressor if you started slugging it with liquid.
f) Best time to charge a system is when the outside temp is at least 70*, and actually 80*+ is better. Makes it easier to get the charge, based on pressure, correct.
*It's smart to wear goggles when charging a system; get a stream of liquid refrigerant in your eye and you can freeze your eyeball and lose an eye. They don't grow back. Just a few observations from the vid that readers here will hopefully find useful.
Last edited by CowboyBilly9Mile; 10-22-2011 at 04:38 PM.
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Mrchuck2004 (05-14-2024)
#13
x2 and those cans dont have the ability to pull a vac./evac the old 134...which needs to be done for a proper recharge
#14
To do a complete evacuation is never required unless the system has been opened for other repairs, had air introduced to it due to a poor prior evacuation or sloppy charging (careless, didn't purge hoses), and surely not evacuated to remove *old* r-134, because it never wears out. Pressure and temp are directly related, as such it's very simple to use a gauge on the suction side to accomplish the correct charge. The suction side, with the engine reved a bit, should be around 32 or so*; this just so happens to be about the temp at that pressures and just above freezing. You don't want the evap to get below freezing and stay there, because it will ice over and stop airflow, and if that happens the pressure will continue to drop until the system is shut off or the probably defective/improperly calibrated low pressure cutout finally kicks in. Undercharging will result in cycling due to the low pressure cutoff switch tripping, overcharging past the correct charge will result in the suction pressure increasing. The way you charge is to slowly introduce freon to the point that cycling stops, watch the gauge, add a bit more, repeat until adding a little bit more (like, 2 oz) causes the gauge pressure to rise. Now vent off a little until the pressure drops to the lowest pressure previously noted. And with this, you're done, service time should be 10 - 20 minutes.
The brute force method, which is a waste of time and money unless there is a valid reason, would be to evacuate using a vacuum pump, followed by using a scale (nope, it's not the bathroom scale either) to measure the change in weight of the jug (typically a 30# cylinder of R-134). I only do this for people that come to me and want to pay more. In 33 years of servicing auto, residential and light commercial A/C systems, only one guy insisted. Ok, I gotta make him happy, and I didn't mind the money, even though I felt a little bit bad about watching him throw it away (and my way). :D
*BTW, air in a system is detectible by looking at the gauge on the high side. Wandering pressure is a good tipoff that there's air in there.
The brute force method, which is a waste of time and money unless there is a valid reason, would be to evacuate using a vacuum pump, followed by using a scale (nope, it's not the bathroom scale either) to measure the change in weight of the jug (typically a 30# cylinder of R-134). I only do this for people that come to me and want to pay more. In 33 years of servicing auto, residential and light commercial A/C systems, only one guy insisted. Ok, I gotta make him happy, and I didn't mind the money, even though I felt a little bit bad about watching him throw it away (and my way). :D
*BTW, air in a system is detectible by looking at the gauge on the high side. Wandering pressure is a good tipoff that there's air in there.
Last edited by CowboyBilly9Mile; 10-22-2011 at 05:03 PM.
#15
In normal day to day A/C use, If your trucks air is no longer cold. your probably a can low (i think they're like 6oz can) Rangers hold 1 pound 6 oz of R-134a in them. you can see this by the sticker on your header panel. It'll be a weight in lbs, oz and a metric (kg) weight.
For the record, I put 1lb, 10 oz in my truck when i redid the whole A/C system. they say your supposed to add 2oz for the hoses.
For the record, I put 1lb, 10 oz in my truck when i redid the whole A/C system. they say your supposed to add 2oz for the hoses.
#18
#20
Bringing an old thread back to life, but I have an 03 4.0L with no cold air anymore. I bought one of the r134 recharge tanks with a gauge. The video posted in this thread no longer shows up (at least for me). I have never done this before but the guy at Autozone said I simply connect the hose with the truck running and let it fill up? Is there a walk through somewhere to reference? What should the gauge read and how much should I let in the system?
Thanks for the help Guys!
Thanks for the help Guys!
#21
Which one did you buy? The gauge usually has a green looking area that the needle will fall into when its charged.
But the guy was right, the end of the hose will only fit in one spot.
Start the truck and turn on the A/C, connect the hose and pull the trigger/turn the valve and fill until gauge reads full, or the air blows cold
But the guy was right, the end of the hose will only fit in one spot.
Start the truck and turn on the A/C, connect the hose and pull the trigger/turn the valve and fill until gauge reads full, or the air blows cold
#22
I think it's called subzero. It's the silver can. I connected it and had no movement on the gauge. It stayed at zero. I could tell there's pressure in the system because when I connect and disconnect the hose, the needle jumps and I hear air coming out. But still the gauge reads zero once connected. I tried it on my brothers jeep to see if it was the in line gauge itself, and it worked on his vehicle. What do you think the problem could be?
#24
Well I went and bought a new can today, the black AC Pro can, turned the ac on max and connected the hose. The gauge shot up to 100, in the red zone. I did not squeeze the trigger since it was in red. I took off the hose and the meter needle is still stuck in the red part. I'm also not sure if the compressor clutch is engaging or not, I do not know where it is or what it looks like. Now I'm not sure what to do next...
#25
Well I went and bought a new can today, the black AC Pro can, turned the ac on max and connected the hose. The gauge shot up to 100, in the red zone. I did not squeeze the trigger since it was in red. I took off the hose and the meter needle is still stuck in the red part. I'm also not sure if the compressor clutch is engaging or not, I do not know where it is or what it looks like. Now I'm not sure what to do next...
On a 1973 Ranger it came with R12, not 134. The change-over started in 1994. You should NEVER add 134 to a 12 system without completely purging and flushing the system and putting in the proper PAG oil. NEVER mix refrigerants (like adding "universal" refrigerant). To use 134 you also need to convert the valves (service fittings). and the 134 capacity is WAY less than the 12 capacity for the same system. Also, generally speaking, R12 systems only have a low pressure cut-off switch while R134 systems also have a high pressure switch to protect the compressor. By LAW the only correct way to fill a system is to draw it down, capturing the refrigerant in the system and re-fill by weight. With 134 filling by pressure is NOT advised and it is very hard to be accurate. A lot of new systems do not even have a clutch, and do not cycle - they have what basically amounts to a variable displacement pump - with a PWM controlled valve in the compressor to control the output pressures.
You really should NOT be screwing with AC if you don't know what you are doing.