Recharging AC

[greenhorn male]

My AC in the 87 Silverado doesn't blow cold. I may have it converted to the new stuff but I have a spare can of R12 left and would like to use this can first. Can some one tell me where to hook up the hose on the AC (a picture will be nice)?. What is the correct procedure in recharging with R12.

[PHOENIX]

You may want to take it into to someone to check for leaks and other possible problems. Unless you have the tool to test the system pressure and search for leaks. They have a die they inject into the system to help find leaks. The old freon is pricy and it would suck to have it leak out in a few months. For an A/C system to works its best you must have good seals all around. I know it wasnt the answer you were looking for but my father does auto a/c systems and I always here him talking about checking for leaks, checking for leaks

[1FaastC10]

you've already converted to R134a, you cannot use the R12. mixing the two are bad for your system, VERY bad.

[PHOENIX]

He said he may have it converted to the new stuff. I take it as he still has the old setup.

[1FaastC10]

my bad, i misread it. still, convert to R134a, you'll be better off in the long run.

[86 Red_Bowtie]

The only thang with converting to R-134A is that you have to make sure that you get all the R-12 oil pumped out of the system. Oh and one other thang they don't tell you when converting over is the you need to change the o-rings in the systm because R-134A will eat them up then you will have a leaky system.

[greenhorn male]

I still have the R-12 system and a spare can of R-12. Yes, I know it has a leak, otherwise it will still be cold. Freon doesn't normally go bad. I'm sorry if I wasn't too clear on my question. If someone has experience in charging one of these using small cannisters of R-12, please let me know:
1- Which fitting do I attach the hose to.
2-When do I start opening the valve to let freon out.
3-Should the engine be running, when should the engine be running, when should I shut it off.
4-How long does it take one small cannister to enter the system.

I'll attach pictures of my system. It's an 87 silverado, 305 TBI 2wd. I pointed out valve fitting locations. 3 is on the line connecting the condensor to the bottom of the evaporator. 2 is under the limit switch pictured.

[greenhorn male]

When I have it converted I'll have it done proffesionally. Thanks 86 Red, I'll make sure they know about the o-rings and old oil.
QUESTION: When you mention "oil", is this something else besides r-12 or r134a that's in the ac system.

[NeCrOmAnCeR]

Yes, all refrigerant systems have oil mixed with the refrigerant. Along with the oil in the compresor. Usually when you buy refrigerant, it is "dry" no oil which means you must add an oil charge (if the system has been evacuated). If you have not had the system apart, or do not notice any oil leaks in the system, you should be OK. The front seal on the compressor will often leak from lack of use, and is usually where the refrigerant leaks out.

The first thing you should do is check to see if the system will operate at all when you turn the A/C on. If the compressor still engages it means that the system may be low on charge, but that it has not totally ran out. When the refrigerant fully escapes the problem is that air gets into the system. Any humidity in the air also gets in and water will freeze in the orifice tube ( our trucks use an orifice tube rather than an expansion valve ) The only way to remove the water is to have the system drawn down (vacuum) to boil off any water. And you would fix any problems before doing this.

Anyways, if all you want to do is throw a can at it, you need to connect to the port you have labeled as #1. This is the low pressure port on the accumulator. Assuming the system still runs (see above)... You have not said what type of gauges/charge hose you have so I will try to explain both:

If you only have a charge hose and can-tap, turn the T-handle on the can tap fully CCW then connect the tap to the can, and then connect the charge hose to the low pressure port (#1), leave it loose on the port for now. Now turn the T-handle fully clockwise to puncture the can. Slowly turn it CCW again till you hear/see refrigerant escaping fron the loose connection then tighten the hose on the low pressure port. You did this to purge any air from the hose. Now turn the T-handle filly CCW again and allow the refrigerant to flow into the system. At this point you start the truck and turn on the A/C to allow the system to draw refrigerant into the system. A pot of hot water will help to speed up this process (put the can of refrigerant into it). When all the refrigerant has been pulled into the system, disconnect the charge hose from the low pressure port and put the dust cap back on.

If you have a gauge set, turn both handwheels closed all the way (clockwise) and connect the low pressure hose to the low pressure port (#1) and the high pressure hose to the high pressure port (#3). Connect the can tap to the middle hose (don't puncture the can yet) Losten the middle hose at the gauge and puncture the can by screwing the t-handle clockwise, then slowly turn CCw till you hear/see refrigerant escaping a the gauges, then quickly tighten the middle hose, then turn the t-handle fully CCW. Start the truck and turn on the A/C. Now open the low pressure valve to allow refrigerant to flow into the low pressure side. NEVER OPEN THE HIGH SIDE VALVE WITH A CAN ATTACHED, IT WILL EXPLODE!!! again, hot water helps to speed the process up. When the can is empty, close the low side valve and disconnect the gauges.

Not knowing how much refrigerant is in your system, 1 can may not be enuf. so this may be in vain. Remenber that to knowingly charge a leaking R12 system is illegal, and that you could get into trouble..

Good luck!!!

[1FaastC10]

Originally Posted by NeCrOmAnCeR

Remenber that to knowingly charge a leaking R12 system is illegal, and that you could get into trouble..

actually, i went through a beginning AC course earlier in the week. that was one of the questions on the test. charging a known leaking system is perfectly legal. sounds back asswards i know. we questioned the instructor, and were told that the EPA allows people to charge known leaking systems, but yet you still cannot release R12 into the atmosphere.

[NeCrOmAnCeR]

Ahh, the fine letter of the law.

Guess he will get fined for purging the hose!

[1FaastC10]

what they dont know, wont hurt them.

[1972C10]

I evac small amounts of r-12 all the time Most of the time when i do conversions i just pull a vaccum on them and charge them up with R-134A knock on wood no problems yet

The next one i am going to do has had the lines open for awhile so it will get a new dryer and a flush b-12 and shop air seems to work well.

The 134a conversions arent hard Ive done a few and they leaked down recharged with some o ring conditioner and as far as i know they There still holding.

[greenhorn male]

Thanks, NeCrOmAnCeR! This is exactly the information I needed.
When I bought the truck, the former owner claimed the AC mechanic told her it would be very expensive to recharge the system with R12 and he recommended that she have it converted instead. She didn't do anything at all. When I got the truck I noticed that the comperessor wasn't turning. When I adjusted the switch (#2 in picture) the compressor started turning but a little noisy and no cold air. When I unscrewed the switch at #2 even before the compressor turned, I noticed it was still pressurized by the hissing sound before I completely removed the switch.
Since I still have a can of R12. I thought I'd try emptying it in the system and hope for a miracle. I didn't notice any oil leaking but I'll look closer. I was going to tighten any loose fittings and check for leaks the old fashion way. I check for and fix methane (natural gas) leaks everyday at work from 1-1/2" pipe down to 1/8" aluminum tubing and different size gas valves. I know it is different with AC as I noticed the tubings on my other PU have o-rings and not just flared or ferreled fittings. But, I thought it is worth the try before I have a Pro convert it to R134a.

QUESTION: Are these my only options? I heard there is a new refrigerant compatible with R12 systems that is inexpensive? What is the average cost to convert my system to R134a when done by a shop? Thanks again!

[1972C10]

If anyone says get freeze 12 that stuff is crap and you have to have a lic to buy it at least in texas you do.

134a is what they are prolly talkin about you can get a little kit at wal mart for like 17 bucks comes with two or three cans of freon a charge hose the adaptor fittings and a can of oil
heck they have big cans that are two cans of freon and oil in one can now ive never used them

Me myself when i convert one I dont put all them fittings on i dont care for them had one leak once and i have seen one get snapped off from hanging out so far.

o what i do is charge with my robinair manifold gauges there for r22 r12 type apps but they work great i have a 134 a can tap charge hose that i cut the quick couple off of and put an old r 12 22 type screw female end on and i can monitor both sides and dont have to buy those fittings for every car .

[86 Red_Bowtie]

The statement that one can may not be enough is true. The fact that it is illegal for one to put freon into a system that is leaking is something that the EPA suppports. A Freon cop will NOT show up at your door, if he does then we are really in a police state in this country. Kinda scarey, the fact that we can't use R-12 freely, but in Mexico they can dump it into the atmosphere without any penalty (cheaply) However, common sense tells you that it will not get better by putting freonn into a system that is already low on freon. It will leak out TOO. Another place where there can be leaks on the older trucks is the hose fittings, where the hoses are crimped onto the hard aluminum fittings. After awhile they will get loose and seep. There is a possibility that you could even grab the hose rubber and turn it on the ends.

[383drvr]

Heres what I've done on my vehicles. I have been running my truck like this for 2.5 years now, still blows ice from the vents. (others are as well after 1 year).

1: Forget the R12 system. Sell the can on eBay or something and pay for the 134A retrofit.

2: Go to WAL-MART, and buy a "134A System retrofit kit". Comes in a box with charging hose, instructions, new connectors, and freon/oil for the entire system. $29.00

3: Go home and completely empty the system, (hold open the valve).

Follow the manual and perform the retrofit. If you can't get the compressor to kick in by following what the manual says, then remove the black sensor assembly (marked #2 in your first picture), and bridge the electrical connections with a paper clip. This will turn the compressor on, allowing you to transfer the freon. Dont leave the paper clip on for more than two cans. Replace it after the second and continue through the third can.

Good Luck

[greenhorn male]

Wow! I didn't expect to get this much response. This is great! Thanks for all the help.

[piecesparts]

Imagine one guy tells you to not put R-12 into a leaking system, because it is illegal, then another guy tells you to just dump the freon to the atmosphere. Ironic isn't it????

[82 Silverado 4X]

In April I bought one of the new pistol grip R-134 injectors at an Advance Auto. It has the pressure gage hooked right into the head. It's much easier to use than the old hose type and so far I've done 8 top offs/recharges with it. Just screw the can on the bottom, hook the coupling to the fitting and squeeze the trigger. When you release the trigger the gage shows how much is in the system. Once full, just unhook the coupling and set it on the shelf in the garage. I've stored opened cans of R-134 for over two weeks while they were hooked to it and lost none of the R-134.

I do have my card to buy R-12 but at the cost of it today I wouldn't waste my money. I converted (just replaced the condensor and put on a new drier) my 82 over to R-134 2 years ago. It only cost me $5.00 this year to top it off.

[383drvr]

I wouldnt recommend releasing a full system into the atmosphere, but he has already noted that it doesnt blow cold. This would mean that theres little to no freon left ( a couple ounces if that). I figure it wouldn't be the end of the world to just empty his system and forego the hassles of evac. But by all means, if I was facing a full system, I'd have it evacuated. But also think of if one just recharged a leaky system with the R12, there'd be 13 ounces leaked into the atmosphere by the end of the season.

[greenhorn male]

If the leak was at a high point (distance from ground) in the system what happens to the oil? I am assuming it is liquid. Does it settle at a low spot. How does one drain the oil. If there is no pressure in the system?

[383drvr]

You have to flush the oil to get it out. I never had done this, and its working for me... You will be fine as long as there is just no freon in the system. However, if you dont replace the accumulator at the same time of the flush with a new dry one, you'll be doing this flush for nothing, as you cant flush the accumulator, and its saturated with alot of oil. I will be doing this full retrofit on my burb.
With that said, for when you do a flush, Pep Boys and Napa carry a big can of flush with a hose. You have to open the system (remove the accumulator/drier) and remove the line from the compressor, hook the flush hose up to the evaporator line and flush it, and then do the same for the compressor line and any others. Dont flush the compressor. Then hook up a new accumulator and replace the compressor lines to do it right. The last step in a good retrofit is to pull a vacuum in the sealed system to draw out any moisture, and then you can finally fill it with R-134. Others may fill in if I left anything out, which I'm sure I have...