Do It Yourself 134a Recharge Kits

[serious II]

As part of an irrational hope that the GREAT ORANGE BALL IN THE SKY will return some day to New England (with any luck, "Summer" may start sometime in August up here) my thoughts are turning to topping-off my AC refrigerant. I have seen some fairly reasonably priced kits at AA (Advanced Auto, not Alcoholics Anonymous) which also have a gauge to let you know when the 134a has reached "critical mass". Have any of you guys used these kits? Are they worth it, or should I just suck it up and have my local GM dealer top off the AC ? The kits have the oil premixed with 134a, so that shouldn't be an issue.


PS. I have been running my AC for 10 minutes every month because I had read that this helps keep the system lubricated and the seals from drying out and leaking. Is this an old wives tale ? Seems logical to me.

 

[goodoleboy]

I have used those before on a truck that was depleted of freon, it worked but it soon destryed the compressor becuase i did not evacuate the system.

 

[serious II]

Did you use 134a to recharge a Freon based AC system? I thought this was a big no-no comparable to "crossing the streams" in "Ghostbusters". Are you sure that your AC didn't die from "134a poisoning"?

 

[jthorner]

quote:

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I have been running my AC for 10 minutes every month because I had read that this helps keep the system lubricated and the seals from drying out and leaking. Is this an old wives tale ?

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I know that in the 70s and 80s some vehicle owner's manuals recommended exactly that, so it isn't an old wives tale.

Most modern A/C systems run the compressor anytime you select defrost and then run the chilled air over the heater core before hitting the windshield. The A/C takes much of the moisture content out of the air which makes for must faster clearing of foggy windows. Thus you may be running the compressor in the winter even if you don't realize it. I do not know which makes and/or models do this and which do not.

I have used the 134a top up kits twice on my '96 Volvo with good results. You do want one with a gauge so you can verify the correct pressure.

John

 

[JHZR2]

we run out ACs year round, and have cars over 10 years old that have bnever had the ac system opened and which work great.

My brother and GF bought used cars, which the AC system didnt worl/work well. My brother's has a leak. I used a gauged recharge system and it worked well to get the right amount in there. Cooled well until it leaked out.

My GF's car didnt cool well, I used a gauge kit, refilled it and it has been super cool ever since. Going on a year now...

JMH

 

[mechtech]

If your A.C. system is a little low, the aftermarket kits are great.
If you are totally out of sauce, you have a leak to fix, and then you will need to evacuate the system. Water will not enter a pressurised system - even if it is lower than what is called for.
BTW, there is aftermarket R134 that is more efficient, and would be a wise choice [better cooling and less HP loss].

 

[Bret Chase]

quote:

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Originally posted by serious II:
Did you use 134a to recharge a Freon based AC system? I thought this was a big no-no comparable to "crossing the streams" in "Ghostbusters". Are you sure that your AC didn't die from "134a poisoning"?

---

I did it to my '88 K2500 last summer... I had 45F outlet temps

all summer. system was completely out of freon due to a leaking shraeder valve. I added a thermodynamics retrofit kit w/ pulling a vacuum or anything.

It should cool much better this summer with the new blower motor I installed... the old one only blew medium when it was on high and made a **** of alot of noise. the new one blows like a hurricane.

the compressor has run with the defroster all winter ( or aleast when it's over about 15F). I'll have to wait until the temp at least gets to the upper 60's to check it out for this year. I might even get the system pulled down and refilled.

-Bret

 

[Oil stain]

I repair a/c systems on the side. If your system just needs to be topped off than the little cans will be fine. You really need manifold gauges to do the job right.

Ok, here's how to do it, (I'll get fan mail over this, I'm sure).

When your ready, start the engine, put a/c on max and fan on high. Put a thermometer in the center vent. Borrow your wife's/girlfreinds meat thermometer. The digital view kind.

Let the a/c run and let the engine rev to 1200-1500 rpms. Let the a/c cool and read the thermometer. Read the coldest temp. As the compressor cycles the temp should go higer and lower.

Once you have the coldest temp, start filling the system with juice while engine is running at 1200-1500 rpms.

Make sure the can is upright, nozzle up. Start filling.

Now the whole can will not totally empty, because it gets very cold and looses pressure.

At this point read the thermometer, if the temp reads lower to your liking, that's it, your done.

If not, then you need to add more juice. By now you have 3/4 of can of juice.

(Here's where the fan mail comes in).

Use a blow tourch to heat the bottom of the can, this will warm and create more pressure in the can. This should just about empty the can.

Am I'm crazy using a blow tourch, no.

Any shop that works on a/c will have a can or bottle warmer to give them the same effect as the can/bottle gets emptyed.

Remember, to much juice will make the a/c blow warmer air.

Hope that helps.

 

[kenw]

a bit simpler means to heat the can is to just warm it in your hands, or placing it on the exhaust manifold works well at the end.

btw, the danger of pointing the top of the can down is that introducing liquid refrigerant can "slug" the compressor. Slugging can damage or destroy a compressor in seconds. just don't do it.

In my experience, hi fan speed and recirculate can get outlet temps (center dash is best) in the range of 35-40F. Since just reading the outlet temp is somewhat misleading, you can't bet too much with this rule of thumb. Outside temp, engine rpm and other conditions affect the efficiency and actual outlet temp. It's better to understand what is "normal" for your car and watch for changes from there.

I usually target about 35F for my cars here in Houston, but often get readings even lower.

Once it gets above 40F, it is a signal that work is due. and if the temp changes a lot (and quickly) with a change in engine RPM, that's also a sign of low freon. Temp output should be fairly consistent across a wide range of engine RPM in a properly charged system, altho slightly colder outlet temps at highway speeds vs idle are normal.

 

[rcy]

Just make sure the can of R134 contains only that. Don't get one that has sealer in it, or even oil unless you're sure you've lost oil. Too much oil will give you warmer temps, and the sealer....well do a Google on 'black death' or go to www.aircondition.com and do the same. You have to read the cans carefully, as some don't exactly advertise the fact that there is sealer - like it might say A/C tune up kit or something. You want pure 100% R134.

 

[mechtech]

I use a judicious application of a propane torch, too, on the single cans. You'd be there all day unless you heat them up, and can't usually make them reach to something hot enough in the engine compartment.

 

[gus_dog]

Instead of using a blowtorch to heat the cans

, I've always used a pitcher of scalding hot water. I just hold the base of the can down in the water until I've gotten all I can out of it. May not get every little bit, but sure is a lot safer than a blowtorch!

 

[serious II]

Thanks for the tips(s). Is there any optimum time of the year to do a top-off? Should I wait until Summer or can I do it within the next few weeks (ie. does the ambient air tempature make any difference?)

 

[Schmoe]

45F is about right, if your doing the temperature control method as described above. You absolutely can't mix R-12 and R134a. The oils will react with one another and you will kill your compressor.

 

[Kestas]

It's probably easier to charge refrigerant in cold weather. The head pressures are lower.

On the other hand, it's hard to gauge a/c effectiveness in cold weather. Vent temperatures are best measured in hot weather. Vent temperatures are one of the important things to look for while recharging. During charging, it's good to spray water on the condenser to keep head pressures down.