Anybody recharged their AC Options

[patred]

I see those DIY AC recharge cans at PepAdvancedZone all the time and wonder if anybody has used them. The AC in my '01 Camaro blows cooler-than-the-engine-bay air. Hope it's not something stupid like the compressor and just a recharge does the trick. I took the AC out of my SE-R so it would be nice to have something with working AC! (IMG:http://www.frrax.com/rrforum/style_emoticons/default/smile.gif)

Pat

[trackbird]

I just charged a friends 2000 Z28 a few days ago. We used a gauge and hose assembly, a can of oil and refrigerant and some refrigerant in a 1 lb can. The system calls for 4 ounces of PAG oil, if the AC still works, it probably has some in it, but I'd use at least 2 ounces (it's a 4 ounce can, 2 of oil, two of R134 and some have some o-ring conditioner in them). His compressor wouldn't even come on and read 0 pressure. We checked the electrical bits and found them working, so I added the can of oil mix, it made some pressure so the pressure switch let the system cycle. We charged it using a gauge and all seems well.

He originally bought those little cans of "ready to use" R134, but I've not seen oil in that arrangement, so I'd buy the charging hose kit (I don't think it's that much) and the standard cans. That way you have a gauge, if you overcharge it, it will go over pressure and vent the system or a large portion of it and you get to try again.

[pknowles]

Yes. It's really easy, just don't over charge the system or it won't blow cold anymore. I bought the hose with gauge that screws onto replaceable R134a containers at advanced autoparts ~$15-$20. Run the car with the AC on for a few minutes to get a good reading for the pressure.

[Cal]

Yeah I've done a number of vehicles. I'm not an expert, but a guy I used to work with was and he gave me a lot of tips.

You don't need to add oil if the system has never been opened up and drained. I think it's hard to get too much freon in if you are using the correct procedure; usually the problem is not being able to get enough in. Just follow the instructions that come with the manifold kit. Hold the can inverted and as high as possible, and swirl the fluid to help it absorb heat. you can even blow on the can with a hair dryer to help get as much as possible out of the can. Get all you can in with the system off, then add some more with the motor runing and the A/C on.

[Todd]

a little bit of advice on using the upside down can method...depending on where the low side port is, be careful not to let liquid refrigerant get to the compressor. On a 3rd gen, you can dump it all in since the low side port is on the receiver/dryer. (not sure where it is on the 4th gen) If the low side port is on the line at the back of the compressor, be VERY careful. liquid refrigerant will hydro lock the compressor...and then its done for. On a fill like that, make sure that after you put the refrigerant in, wait for it to expand (ie temp on lines comes back to ambient from frosty)

[trackbird]

On the 4th gen, the fill port is on the accumulator. I filled the 2000 with the can upside down. And, since it was almost completely empty, we "assumed" the oil leaked out with the freon. So, I added 2 ounces. Your results may vary.

[Cal]

Yeah I was going to say something about that high side/low side caution but I couldn't remember, and my expert is out for the count with a medical condition. True story about hydrolocking the compressor. Seems like there is also a risk of bursting the can if you feed the high side with the compressor running.

Also important is there are two kinds of freon and two kinds of oil, none of which can be mixed. 3rd gens use Freon 12, 4th gens R134A. You can switch a freon 12 system over to 134A if you get every last drop of the old oil out and repace with the PAG stuff.

A manifold set with high side and low side gauges and valves is a good investment and will alow you to do a better job. Seems like the low side should be around 30 psi and the high side 240 psi? Again, CRS so verify this first.

In the case of a system that is empty, especially if a coupling has been taken off so outside air can get in, you need to pull a vacuum on the system first or it will never cool worth sh*t even completely recharged with freon. You can get a cheap venturi vacuum pump from Harbor Freight or make a real dandy one from an old fridge compressor that will pull a couple more inches of vacuum. Suck it down for 20 mins or so, then let the freon in. This way the system has mostly freon and no air. By the same token, if the tubes are going to be off for a while, plug the open ends to keep humidity out.

If all else fails, pull the whole system off making the car 60 lbs lighter!

Oh yeah, and if you ever need to bleed the system, let the freon out real slow, that way the oil won't be sucked out with it. Then you can refill it without adding oil. It is also bad to have too much oil in there, so don't add much unless you are pretty sure it is low.

This post has been edited by Cal: May 21 2007, 08:37 PM

[pkincy]

I have done it on several motor rebuilds with no ill effects as mentioned in this thread.

Be advised that a mechanic will pull a vacuum on the system to purge water vapor. So by doing it this way we stand a chance of having water vapor in the system.

Perry

[CMC#5]

I've seen vacuum pumps at places like harbor freight for next to nothing. Is that all that's needed to completely empty the system and ensure no water is in it?

[35th_Anniversary...]

I tried one of those R134a cans, held it upright, possibly overfilled it, reads ~25 psig now, before it was 0. Still no cool air, but i have no idea what i am doing if I don't have a wrench in my hand, this HVAC crap is new to me.

[rpoz-29]

I've been told it takes less 134 to charge a system than R-12. Maybe you need to bleed a little off through the schrader valve? I've converted 3 vehicles to 134, and discovered I had overfilled the first. I bled a little off, and it worked fine. Are you converting, or re-charging?

[patred]

Well it looks like I have a leak somewhere. I tried recharching last weekend, gauge read about 25 psi as I was filling then went down to zero. Disconnected then re-connected and the same thing. The needle was down to zero the whole time as the silver thing that you fill up was cold with condensation on the outside, but then it went back to "room temperature." I thought maybe the gauge was bad but it read OK on Karen's green Camaro.

Pat

[CamaroFS34]

I thought maybe the gauge was bad but it read OK on Karen's green Camaro.

Which, by the way, blows cold. Even after all this time. (IMG:http://www.frrax.com/rrforum/style_emoticons/default/laugh.gif) (IMG:http://www.frrax.com/rrforum/style_emoticons/default/wink.gif)