Recharging my A/C - questions

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Greetings,

I have a 2003 Lexus GS430. Now that Spring is here, I notice my A/C does not cool well at all. My air conditioning system has never been worked on at all for the entire history of the vehicle (I am the original owner, with about 107,000 miles). I suspect I am low on refrigerant.

I know that loss of refrigerant generally means a leak somewhere. But I'd like to try to re-charge it first - if that improves cooling but gets worse again in a short time, I will know I have a leak - at that point, I'll probably have a professional look at it.

Meanwhile, I'd at least like to recharge it myself. Questions:

1) Should I invest in a good manifold gauge set? How much does a good set cost, and where can I buy one? Is there a good brand someone can point me to?

2) I notice the auto parts stores have large cans of 134a refrigerant with gauges attached to them. Is this good enough for a do-it-yourselfer? Or should I go only with a decent manifold gauge set (Hence my question above)

3) If I purchase a manifold gauge set, will any "brand" of R134a refrigerant be OK? In other words, is one brand "better" than the other?

I have a factory shop manual for my vehicle, and it shows several examples of diagnosing problems depending on what a manifold gauge set shows. I am assuming a decent manifold gauge set costs at least $200 - hence if the all-in-one cans of Freon with attached gauge will suffice, I'd rather avoid purchasing the manifold set.

Comments? Advice?
 
Originally Posted By: Eddie
A can of refrigerant with a gauge worked well for me.
Those do work, but having a manifold gauge set is the proper way to do it. Seeing both high and low side pressures is best.
 
Yes it's possible to get it close with low side only gauge but some vehicles are more sensitive to others to an over fill. The manifold gauge will help you make sure your high side pressure is right.

On some vehicles an over fill will keep the compressor from turning on then you have to have the shop evacuate it or purge illegally... Not fun.

As far as the refrigerant, buy any brand r134a it's all the same. Buy the cheapest you can find, make sure it's only refrigerant, avoid anything with stop leak or additional additives which are not necessary and can clog a machine at the ac shop if they don't have the proper filter.
 
Before you spend $$$ on a nice gauge set, check to be sure you have both high & low ports. The sled only has low. Frustrating, but there it is.

All brands are the same. Just be sure you get 100% refrigerant with NO sealers, leak stop, etc.

I wouldn't and don't trust those cheap gauge-on-a-can types. I periodically top mine off by watching for the beginning of sweat on the suction line. When I see that, I close the valve.
 
The HF gauge set is fine. No need to spend more than $50. Also get a temp probe you can stick in a few inches into the AC vent. Knowing the temp of the air in the vent is necessary.

And remember after connecting things up but before puncturing the can, unscrew the can slightly and let a tiny bit of R134a escape. That will purge the line of the manifold gauge set of air.

Keeping the can of R134a in warm water (while its going into the system) helps to boil off the R134a inside the can quicker.
 
I use this interdynamics chrger mentioned here: http://idqusa.com/product/acp-100_acproprofessionalformular-134arefrigerantautoacrecharge

That is because I have used ones with plastic hoses, and ended up melting the hose.

It worked perfectly in mom's 2005 Jeep Grand Cherokee and 2011 Mitsubishi. I may have used it in dad's 2007 Pontiac G6, but I don't remember.

Read carefully the contents of refrigerant cars. Having UV dye is fine, but beware of ones that contain methanol or leak stopper.
 
for your 2003 if there's no signs of ac oil leakage anywhere,
get a can of r134a only with whatever mechanism they have to dispense it into the low service port. don't get anything with oil or other additives. get a $10 digital temperature gauge from the kitchen section at walmart that you can stick in the vent to measure air temperature.
have someone sit inside car keeping rpm's around 1000-1400 monitoring vent temp. dispense r134a into system slowly until vent temp get's 55° or colder, but be careful not to try to keep dispensing hoping vent temps keep getting colder below 55°. that's how you overfill it without using a gauge set to measure high side pressure.
the small cans you can buy i wanna say are 12oz, those you typically need a gauge set and can tap to use. the cans you buy that come with the dispenser and low side gauge are 16 ounce or more, they are bigger. for your car if you were to use the small 12 ounce can you would only want to use 1/2 of it which is 6 ounces, i say that because you seemed to indicate your ac sort of works just doesn't get cold like it should. that's means you are slightly undercharged, most systems have a capacity around 1.5 lbs which is 24 ounces. so if you got the big can with dispenser you "should" only need to add a little and the vent temp should immediately get colder as you do. if not you have another problem, and you would need a gauge set to observe both high side and low side pressure to know.
 
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