Any A/C Guys here?

[Greg L.]

I was wondering if there are any A/C techs here that could clear up some questions for me.

The A/C in the 94 my wife and I bought doesn't work.I hooked my gauges up and there was no pressure so either someone had the system open or there is a leak. I connected my vacuum pump and got it down to about 25" and stopped. I was suspecting a leak but with the manifold valves closed for the past 72 hours and still holding at 25" I've ruled out an obvious leak and now assume that it has just leaked out over the past 26 years or someone had the system open. Regardless, it's not leaking now.

Now it's been quite some time since I did any real A/C servicing. In fact it was back in the R12 days when things were for the most part unregulated and back then I would just connect the R12 tank and recharge the system. My problem today is that due to regulations(yes I'm in Canada) I can't buy a tank of R134a. I can still however buy cans of refrigerant that is supposed to be R12/R134a compatible. My questions is, are any of these "top-up" refrigerants okay to use for a full recharge? Are some better than others? Can they really be mixed with R134a?

My concern is that I don't want to damage the A/C system with some low grade refrigerant. My concern comes from a top-up kit that I used on a 91 VW about 10 years ago. It worked well but then the compressor seized about two months later. A friend from work also tried the same kit on his 95 Chev 1500 and two months later his compressor also seized. The product we used was Dura Cool and we didn't use a manifold gauge set, just the low px gauge that was supplied with the kit. I don't see it around anymore but I'm still a bit apprehensive to use something other than pure R134a.

What do you guys think? Will these top up kits work for a full recharge or should I be concerned about using them?

[Peter H.]

Re: Any A/C Guys here?

Greg ...Fellow Canadian Here . I Would Go To Your Local GM Dealer Or A Cooling System Specialist and Have Them Evacuate And Recharge Your System . They Can Add A Dye And Use A Black Light To See If You Have A Leak And Where . Good Investment To Let The Professional Have A Look At It . Peter H. # 3522

[Tom E.]

[Harry S.]

Re: Any A/C Guys here?

This is what I use on my C2 with R12. It worked for me.

https://www.elitechustore.com/products/elitech-wjl-6000-corona-refrigerant-halogen-leak-detector-hvac-r134a-r410a-r123-r22-air-check-freon-sniffer?_pos=5&_sid=d4ce62517&_ss=r

[Edward J.]

Re: Any A/C Guys here?

Greg, sometimes when you can draw a vacuum and no leak just replace the scharadder valves they can leak. I would just do it for safety purposes. Also when the a/c system looses its refrigerant it will leave A very slight amout of oil that collects dust around those fittings. If you do see this then just replace those rings in the system.after they age they tend to get hard and flatten out and can have small leaks,

[Dennis C.]

Re: Any A/C Guys here?

If your gauge is accurate and you can only pull 25" of vacuum, that is a sign of a leak, preventing you from pulling a deep vacuum.

Getting certified to work on automotive AC system is a relatively easy thing to do online. You read a short manual, pay a small fee, and take the exam.

[Tom L.]

Re: Any A/C Guys here?

What the other Tom said X 2.

Occasionally you may have a leak that doesn't show up in a vacuum, only under pressure. If you have dry nitrogen available put it under 10-15 lbs of pressure and see if it holds. Also, pull a vacuum on your gauge set and make sure the gauge is accurate. If the gauge isn't spot on you might not have a problem. If you don't have a leak detector try soap and loo for bubbles. Messy but works well. Finding leaks is a skill, one that requires patience, persistence and some tools.

[Joe L.]

Re: Any A/C Guys here?

Greg ...Fellow Canadian Here . I Would Go To Your Local GM Dealer Or A Cooling System Specialist and Have Them Evacuate And Recharge Your System . They Can Add A Dye And Use A Black Light To See If You Have A Leak And Where . Good Investment To Let The Professional Have A Look At It . Peter H. # 3522

Peter and Greg------


I agree. I think going to a GM dealer or auto A/C specialist is definitely the way to go. I would definitely not use any refrigerant in the system other than R-134a.

[Greg L.]

Re: Any A/C Guys here?

Thanks guys, that all good advice.

So I've decided to go with pure R143a and I've ordered some of the Dupont R134a cans from Amazon. Not sure why these cans are safe but a 30 lb tank isn't up here but at I'll take what I can get. I also think I'll call around and see what the dealer and local corvette place will charge for a refill. If the price is okay I may just do that and keep my cans for down the road when R134a is banned like R12.

Now if I do end up doing the recharge myself I was going to replace the schrader valves anyways and I guess replacing the o-rings would be a good idea too. I can only assume my gauge set is accurate without sending them out for calibration. I suppose I could tee in my old R12 set and see if they both show the same vacuum. I know 30" is the number to shoot for but I was told that at 3,500 feet I wouldn't get 30". Not sure if that is lies or bs but that what I was told. What does make me think that the system is tight is that it maintained this 25" vaccum for about 5 days now and didn't drop at all. Also no signs of any oil weeping from connections to indicate a leak either but pressure is another thing, we'll see.

I guess for me it's the principle and challenge. I used to do AC systems when I worked in the garage in the late eighties/early nineties. For the most part it was like any other job that came in, pretty straight forward especially with a scenario like I have. It's been a while and I'm obviously not as current as I once was but with the proper prep it shouldn't be an issue if I do end up going that route.