How Hard to Charge car A/C Yourself?

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How hard is it to give your car a shot of R134A or whatever? How do you know how much to put in, or does it take only what it needs? Talking about those DIY cans in the auto parts store. I cannot find any visible leak, just looking for oil on the lines which would seem to be a clue since the freon has oil in it. Unless the leak is in the evap coil buried in the dash.

Not completely sure what's going on. I loaned the Forester to a friend for a few weeks on account of his car got totaled in a hit & run. AC isn't working as good as of getting the car back today. Before, the compressor would cycle on and off frequently, but now it stays engaged without disengaging and the air isn't as cold as before. Condensing coil at front of radiator is clean, not bugged up.

There is a chance it's the compressor. It made a quick momentary screech when engaging upon switching on the A/C tonight, when messing w/ it in garage. And the car is a garage queen sitting in garage through week and maybe getting out on weekend (or not), due to fact I drive an employer provided Ford Fusion to and from work and can use that car for personal errands at will, too. So I'm thinking maybe the compressor might just be going south from lots of parked time then being used steady for three weeks in really hot weather.
 
Those cans keep us in business! You don't know how much to put in. The low side gauge is a Gimmick as low side pressure has nothing to do with high side pressure. And high side is what you need if not using a scale.

My summer is spent sucking out overcharged systems after the customer goofed with it.
 
It is not hard, it also isn't hard to overcharge the system. I have seen several vehicles lately come in for a/c problems that I found had been overcharged. Since the compressor was cycling before and isn't now, I think at least part of the problem is increased ambient temps.
 
I am not %100 familiar with the AC in your Subaru but a compressor will normally cycle more often when it get low on refrigerant or not run at all. This is the opposite of what you say is happening.
It shouldn't cost much for a professional diagnosis.
If you are sure you are low on refrigerant those cans with gauges can work well for small top ups.
 
Get a hose that has a gauge
smile.gif
 
I notice with my Subaru when recirculate is on, the compressor will cycle on and off frequently, and obviously the air is colder with recirc on. I notice when recirc is off, the compressor stays engaged longer.. So I just have to check... maybe recirc was on before, and now it's off? My AC performance is terrible with recirc off, I have to keep recirc on to have vent temps below 50F. I'm not sure if anyone around you will rent out a manifold gauge set, you can check the pressures that way. I'd check the pressures with a manifold gauge set before doing anything.
 
The screech could be the clutch slipping, maybe your friend already overcharged it.
 
LoneRanger

I evacuated and recharged my system in May 2017 for the first time ever. It was easy and my AC was ice cold afterwards.

The vid in the link below should help you but do some more research. You can borrow the vacuum pump and manifold gages at AZ and other parts stores. Make sure your wear protective goggles and gloves to protect yourself from the refrigerant in case something goes wrong.
Good luck.

https://www.youtube.com/watch?v=Pdq8JAlct6s
 
It's easy to mess up, but there are stapes you can take to prevent this.

Stick a thermometer into the center AC vent and get the temperature. Then slowly, maybe half a turn of the valve, and about 10-15 seconds at a time, add the refrigerant. Each time take note of the vent temperature, compressor cycling behaviour, coldness of the return line and the pressure. I'm not sure about Subaru, but low 40s vent temp is a good target and safe target.

If you just hook up the can, fully open up the valve and expect to catch the magic full point on the gauge, you will most likely mess up.
 
Not hard. But you gotta take your time and go easy or you can overcharge. I know from experience.
 
It's not hard if you have the right tools and follow the correct procedure. I learned how to do it by going to AC forums, reading books, asking questions and watching videos.

I bought a vacuum pump, gauges, weight scale and other various AC tools and went to work on one of my 92 Cavaliers which I converted over to 134a. That was a success and since 2006 when I did my first car, I have fixed the AC in approximately 15 vehicles.

My latest repair was doing my other 92 Cavalier which I had done previously about 10 years ago. The compressor started to leak so I had to do it again. I kept this car R12 and it blows ice cold.
 
Just pay a shop to evacuate, weight the charge, and recharge with the proper weight. The shop across the street from me doesnt have a machine and uses gauges and a 30lb bottle, and every 1 out of 5 jobs he ends up screwing it up and overcharging it or having no idea how much is in there. One time he took the entire console out of a GMC Terrain to get to the controllers since it was only blowing on the passenger side, and it was because he didnt have enough in. I recovered about 3/4 of a lb and it took 2 lbs. Simple recharge, and handed it back to him for the 3 hour reassembly from not doing it correctly and chasing his tail around the car.
I also frequently see these systems overcharged from these recharge cans, same idea, no clue about the weight or pressures in the system.
 
If the A/C system is low on refrigerant, it has a leak that should be fixed.

If you are going to try yourself, you need a manifold gauge set (high and low). Only R134a. No stop leak.
 
If the A/C system is low on refrigerant, it has a leak that should be fixed.

If you are going to try yourself, you need a manifold gauge set (high and low). Only R134a. No stop leak.
 
Hey guys, thanks a lot for the help and suggestions. I think I might be able to get ahead of this problem. I went out and examined the car again this morning and virtually zero evidence of any leaks on the lines at compressor or elsewhere under hood-- all dry and clean. LED flashlight all over what i can see on the condensing coil at radiator and no evidence of any peens or dings that might have perforated it and caused leak there, but who knows because given that it was blowing ice cold before and now not as cold best theory would be rock or piece of whatever hitting condense coil enough to cause leak. But then the coil is pretty well protected up in there, lot of bumper and grille up there.

There's a magic handshake I can do that will display codes on the odometer LCD. Going to check if code P0534 is set, which is supposed to be Low Refrigerant.
 
Put about 3 or 4 cans into my Rav4 the last couple of years. I can hear the compressor getting happy as the refrigerant is added. But have a hard time getting enough refrigerant into the system to make the gauge to into the "full" area.

There are widely variable prices on the small cans of coolant. Check Walmart. Picked a couple up there for $5 each. You'll also need a guage and a tap. The tap is hard to come by and I ordered mine off Amazon. I have the HF A/C gauges but sometimes just use the cheap gauge that came with a can.

For a newer car, you might want to take it to a professional. For an old beater, I use the cans.
 
Last edited:
Originally Posted By: sxg6
I notice with my Subaru when recirculate is on, the compressor will cycle on and off frequently, and obviously the air is colder with recirc on. I notice when recirc is off, the compressor stays engaged longer.. So I just have to check... maybe recirc was on before, and now it's off? My AC performance is terrible with recirc off, I have to keep recirc on to have vent temps below 50F. I'm not sure if anyone around you will rent out a manifold gauge set, you can check the pressures that way. I'd check the pressures with a manifold gauge set before doing anything.


The older Subaru compressors cycled in normal operation once a certain temperature is reached even in a perfect and properly charged system. They used this method to prevent evap core freezing.
 
I put in a new compressor and various parts last year in my Accent. Filled it by weight. The compressor would seldom cycle. This summer hooked the gauges back up and at 90F ambient filled until the high side was around 250 lbs. It now will cycle with 38F air coming out of the vents.

Used this chart.

 
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