AC parts

[Twisted Steel Performance]

Well, last year I had my entire AC replaced with new parts, It never cooled like it should have, the shop only put 42oz in the system, everything I could find says 3 lb or 48oz, the new condenser had a tube installed in it, the old system had it in the dryer line..
We almost never use the truck so it sits covered in the barn... I went try the AC today and nothing, the clutch wouldn't engage.. I will be hooking the gauges to it to see if the system is empty or low later today..also I'm going to purchase a vac pump as well..

A few questions..

What color orifice tube should I get ...
Would it work better to install the tube in the dryer line and not the condenser..
If it is low or empty, do I add more oil to the system...

Now, I see there is several types of refrigerant, what are your thoughts on "Arctic Freeze" synthetic... what would the best refrigerant be to use...

 

[WarWagon]

What is this in?

Generally the AC system looses it's charge through a compressor shaft seal if it doesn't run for a long time. Like all winter. Look for oil that leaked out of the system on connections and the body of the R4 compressor if equipped. They leak at the body O rings and at the area where 4 bolts that go through the compressor. Generally no oil is added for an evac and recharge due to a slow leak.

Arctic Freeze is alright IMO was a touch colder. OEM orface tube in condenser and insulate the liquid line to the evaporator. Wrap the Accumulator in insulation of some kind. A Dryer is in the accumulator but that term is for TXV systems that have it on the outlet of the condenser or an all in one TXV unit on the evap nowadays. You can try the VOV, variable orface tube as they improve the systems a lot at idle, but, many are DOA - plugged solid and don't work. Maybe the bad batch is gone now.

I am a fan of the HC refrigerants like the Envirosafe as it gets colder than R134a because it's more efficient (The industrial they offer is too cold for our systems low pressure kick out switch and will turn the evaporator into a solid block of ice even in our dry climate). As the new R134a replacement R1234yf is also flammable... Only the high end cars are using the CO2 refrigerant to avoid the flammable stuff.

Leaking body O rings just sitting...

 

[Twisted Steel Performance]

I just checked everything, no signs of leaks, every connection clean and dry, and there is o pressure in the system...
And this is my 93 dually..
Looks like I'll be redoing all the o rings and a new tube this weekend...
Someone tell me the better can type of refrigerant to look for...

 

[Will L.]

Did you pit dye in the system? If not, I really suggest doing it this time.
Idk best refrigerant to use, kinda wondering myself.

as to vacuum pump, I bought the basic one from harbor freight and it has done great for multiple uses and years.

Charging a system by using exactly X amount by weight is a generic method really. It works good on the assembly line because they just build a couple rigs, have a regular a/c charge done by testing sub cooling and super heat method of charging. Then decide on performance vs cost of material saved and make that the standard. Then that amount is given as a spec that everyone copies. Because the refrigerant is not exactly the same as what it once was- the exact amount by weight no longer performs the same. Keep in mind the amount to charge by weight is not what makes it work the best. It is the middle of a range- not making what works best as target but between how little can we use and peak performance.

There was a super wazoo a/c guy that worked at a fleet I wrenched for. He was retired a/c engineer. He would take brand new vehicles the company bought and charge them to peak performance. He was neighbors with the company owner. So he worked about 3 days a month, every time the new cars added into the fleet. He showed me how to do it that method, a clamp on temp gauge- 2 different places, measured ambient air, take readings, do math and add until pressure hit “X”. I didn’t take notes because It seemed simple enough I figured I would never forget. Oops.

I know we have some serious a/c pro people here- maybe they can explain or do a video how to properly add refrigerant based on sub cooling and super heat. Even vacuum a system down- automotive says do it “X” long in minutes. Real a/c guys use a micron meter ... automotive is way more shoot from the hip rather than actually determining best and getting it there in a controlled manner.

 

[Twisted Steel Performance]

Well I'm tired of paying shops to do work and it costing a wad and lasting a very short time, I'm getting a good vac pump tomorrow. If I can find a dryer, tube, and a seal kit I'll attempt it myself, I think I can figure it out and follow the pressures.. I will use the cans with dye already in them..

 

[Twisted Steel Performance]

Maybe @THEFERMANATOR can advise me as to some of the tricks to look for, I'm going to remove the tube from the condenser and put it in the line at the dryer where it started off being, I don't mind a little hissing sounds if it works better, and I got a self adjustable tube as well as dryer and seal kit, but I don't know if it has the correct thickness seals for the compressor ....

 

[Twisted Steel Performance]

Also, I'm having trouble finding a condenser for R134, and I think the dual air burbs used a condenser that was thicker, but I can't locate anything in a part number, my other stuff is coming from napa and if I can find a part number I'd see if I can get a good condenser as well...

 

[MrMarty51]

A friend that lives over in Elko Nevada is just getting into the vehicular AC business.
He bought the 134 recycler and right away had a job. Pulled vacuum on a Dodge diesel, seemed okay, charged it up. Next day went out and nothing. So then he was trying to find the leak.
He called and we talked after he got that fixed and before charging it back up.
I told Him, no matter the cost, always give them things some dye upon the initial charge.
He said He would definitely be doing that from now on.

 

[THEFERMANATOR]

Unfortunately GM discontinued the r134 conversion condenser for 91-93's and they've all gone to a 1 size fits all condenser(the thicker suburban unit). The factory charge is 2.25lbs of r134, the 3lbs was for r12. Unfortunately r12 used sae threads and r134 used metric threads, so you can't just swap in the 94+ larger r134 condenser. The oricice tube typically goes in the condenser, but you can also install it into the evap entrance, but you have to use one meant for evap install as the condenser install type is different(the nubs that the orifice tool remover latch onto are on the outlet side on a condenser install, but on the inlet side on an evap installed type. If you replaced the entire system you could go with r134 parts, but I don't know if the larger r134 evap would fit into an r12 evap box. The biggest problem facing most of these trucks is they're 20+ years old and the evaps are plugged full of crap rendering the AC to poor performance regardless of what you do. Both of mine have newer evaps and will blow icicles.

 

[WarWagon]

Idk best refrigerant to use, kinda wondering myself.

Charging a system by using exactly X amount by weight is a generic method really.

There was a super wazoo a/c guy that worked at a fleet I wrenched for. He was retired a/c engineer. He would take brand new vehicles the company bought and charge them to peak performance.

The best refrigerant would be getting some R12. Otherwise HC refrigerants. I walk back my Arctic Freeze synthetic comment as it appears to all have the recycle machine killing leak sealer in it now(!) Avoid it! (It was sold without the leak sealer crap before. And R134a is natural? No it's all synthetic. ) Open your AC system for repair and just simply replace everything as the leak sealer cures and clogs things up when air hits it...

By the service manual one charges the system by weight, period. GM, Dodge, Ford anything orface tube is exclusively by weight. For backyard mechanics the only way to charge the system is by weight. The other method all but requires a wind tunnel and being an AC engineer. EASY BUTTON: get the proper tools to do the job: buy/rent a scale that can weigh the refrigerant. At the end of the day the only thing most asking want is for the damn thing to blow cold air until cooler weather and they can forget it.

Tools for AC work:
1) Rent a shop to recover the refrigerant unless the system is empty. R134a is expensive and we are environmentally friendly here.
2) Vacuum pump.
3) Scale to weigh that last bit from a 12oz (short of a 16oz LB) can to get the exact oz the system requires.
4) Gauge set.
5) Leak detector.
6) A baggie of schrader valves you change every time you touch the service ports.

I have 1-4 as an all in one. I also have most of them separate as well. I have $2000 into it used including repairs like new filters, hoses, oil dump solenoid, and a new compressor as it "quit" when the compressor flooded with recovered oil that wasn't dumping. #5 can be dye, but, GOOD LUCK on shaft seal leaks with dye. (I have made it's money back on friends AC repairs let alone my own junk.)




The OEM engineers fill the evaporator up with liquid refrigerant and add 1/4 to 1/2 LB extra as a leakage reserve and for system load changes. (Likely less today with the EPA wanting less R134a per car. My 2018 pickup is just over 1 LB aka 1/3 of the 1993 systems. The old above unit isn't accurate enough for the smaller systems.) The lengths people go through to try and not evac and weigh the refrigerant they are adding to the system to get poor results is unreal. The same place one rents a vacuum pump from will also rent you a scale. And by $then$ one payment per year to the AC shop, renting their experience and tools, and you are on your way with cold air isn't a bad plan. Neither is dropping $5000 or more on the proper tools to do AC work.

 

[MrMarty51]

I know enough about AC shstems to get into trouble, aaand, spend a lot of money.
I have found it is cheaper and easier to take the truck to the shop and rent that guys knowledge and experience, for less than $100.00 about every four years.

 

[Twisted Steel Performance]

Well the only thing that I haven't replaced is the evap core, I ordered one so this time I'm doing a complete replacement, now I will need to figure out how involved the evap core is to replace, doesn't sound like much fun...
Thanks for the info everyone...

 

[Will L.]

Maybe go to a local parts store if they have the 12 and 134 evap in stock to see if it looks like you can fit it.
If you are replacing it anyways and can’t get the 12, get the one they designed for 134

I will confirm what WW is saying about the leak sealant garbage- never add that junk to any system. If you already have, you HAVE TO have the system vacuumed down into recovery because if your (ehem,,) mechanic accidentally- removes a line somewhere and it bleeds to atmosphere- it will try to seal and inside the evap, condenser, valve, compressor- just everywhere that turns into a nightmare. Even when you get a leak- normally that happens at the compressor, or orings. IT DOES NOT FIX THOSE LEAKS!!! It will slow them but they will still leak by. So it is worthless anyways. Then there is this tidbit. The oil in your system is A necessary evil, only the refrigerant make sure system works good. Everything in there other than the refrigerant slightly lowers the performance. Yes this does include the dye- but so little dye is needed and helps so greatly in finding leaks that it is well worth it in any system that runs 1lbs or more imo.

I must say, driving the ‘08 3500hd at work- gm got the ac working good finally. Not amazing, but good.

@WarWagon No, much to my surprise, it isn’t a huge involvement having a commercial a/c guy do it by pressures rather than weight. Mind you I am talking top dog craftsman worker here, not every dude that went through a 4 month school. Their training, knowledge, and equipment is superior most of the time. Because they learn the systems and science behind each one, and learn one design can be amazingly different than the next, most will never touch automotive. The idea of random variable speed compressor not being commanded to alter compressor by refrigerant demand- freaks them out when they learn of it. Guys at work (regular home size ac to huge systems and laboratory equipment is their norm) and I got into a conversation about automotive a couple years back and it took them about 3 minutes to decide automotive engineers are dumb and should just make electricity and run a proper vfd controlled compressor instead. Haha. Anyways they know the slightest difference can make a system great or junk- so they don’t want to touch it. But the few guys I met that understand auto and commercial systems well- those guys will get a snow flurry from a yugo.
Think a out how we diagnose a system- all pressures and temperatures throughout the system. Thats how they have to do it on huge systems and not like they can recover and recharge 25 ton systems each time.

Also Didn’t realize that was your machine btw. Thats the one that ruined me. It worked so well, that what we went to and we jumped to recover, add dye and since that one measures the amount of recovered oil separate, add that in and charge it up. Then with the charge right and see most leaks easy, we diagnose from there. Fleet mechanics got me the easy button- but lazy diagnostics made me loose my skill. Cannot remember even half what I learned because 90% of the time leaks was the issue so I never got deep into diagnostics again.

 

[WarWagon]

@Will L. they have electric compressors on cars now, finally.

Although it's possible to charge by temperatures there is one quirk of the orface tube system that temps will not show you: how much liquid refrigerant is in the accumulator. I doubt the bigger systems use an accumulator in the way the automotive systems do...

In the bad ole days before AC and rear bumpers were standard aka options... The first AC system I worked on was a 1987 S-15 with aftermarket AC 2.5L 4 banger with 4 on the floor. It had a sight glass on the dryer coming off the condenser. (TXV) 4 blade direct drive engine fan, ugh. Not the cheap orface tube accumulator Detroit was in love with because: cheap. Larger compressor that looked like a Sanden. Didn't work worth a damn. Lots of bubbles in the sight glass. So a buddy's dad, who did commercial AC, hooked me up. 30 LB R12 jug. It was a long time before all the bubbles mostly went away.

Still sucked. We were all scratching our heads.

So taking a close look at the system there was an "in" and an "out" stamped on the dryer. Someone had installed it ass backwards!

There was frost on the condenser as the shop recovered the system for me. No charge as they "made money" from the insane amount of R12 that was in the system. Turned the dryer around vacuumed the system and charged it with cans till the bubbles in the sight glass went away. I don't recall if it had a system charge sticker on it and I went by can oz as well.

The second system I did was a buddy's 1969 Buick. No, never thanked for fixing his AC rather complained about it as the word "Economy" on the HVAC control became real clear to him. The AC made that car drink gasoline even faster, if one thought that was even possible to do with MPG that low to start with.

Been looking for a way to avoid the scale, and evac step, on an orface accumulator system ever since that TXV system. Because I haven't always had the proper tools around.

 

[MrMarty51]

I loved the sight glass system. I was almost a AC pro with that system.

 

[Twisted Steel Performance]

OK, parts will be here tomorrow, it may take me a weekend or two to get the evaporator replaced.

Last question.... replacing the evaporator and dryer, how much oil do I add to the system changing those 2 items, and do I add it in a line or in each item, and I think pag150 is what was used during install 2 yrs ago and 8oz was put in then when everything but the evap was changed...

 

[Husker6.5]

I remember that good old sight glass system. My '72 402 BBC Monte Carlo had a factory A/C system with one of those.

Now my '72 Dodge Adventure Sport D100 p/u had that monster Chrysler V-2 A/C compressor on it that made a kick-ass air compressor when hooked up to an electric motor and tank! I wish I had kept that compressor when I sold the 360 motor out of that truck when I parted it out.

 

[EWC]

I'd put 1 oz in each part .

 

[Jaryd]

If you want to buy a good vacuum pump that isn’t crazy high $ I would go to a HVAC parts house and get a Robinair vacuum pump. For a little over 100$ (Last I bought some) you can get a micron gauge there to.

I’m not a vehicle A/C pro by no means but this is what I have always done.

Anytime I had the system open I would change out the dryer. I had a cheap set of hose adapters to hook my gauges up to vehicles but quickly found out I needed to spend the money on a good set of adapters. Using nitrogen I would pump the system up to 500 lbs and let it sit for about an hour. It is easy to find a leak after about 400 lbs. Nitrogen is cheap at a parts house. You don’t want to use air because of the moisture. If you pump it up and have a leak but can’t find it on the vehicle start spraying the fittings on the hoses because the o-rings in the hoses will leak sometimes to. If it passed the pressure test I would pull a vacuum down to 500 microns and let it sit for about 30 minutes. If you can pull a system down that low then you know there is no moisture in the lines. Going down into the vacuum scale on the gauges without a micron gauge you can’t really tell how much vacuum you actually have. You just now that’s it’s in a vacuum state.

I always use hoses with ball valves at the fittings so that when I was done with my vacuum I could shut the ball valves off and not loose the vacuum in the hose while hooking up to the Freon jug. I have always used Yellow Jacket gauges and hoses. Most people don’t know it but the red, blue, and yellow hoses ain’t meant to be used to pull vacuums. But they will work for a while using them for vacuums. Vacuum hoses are actually black and are made specifically for that.

I used a scale to measure how much Freon was going in but I always used a pressure chart I found off the internet to get it right because I never knew how much to put in based off of weight. A bathroom scale don’t work for this because it needs to measure ounces. You could get the scale from the HVAC parts house to.

I never really liked using the little cans with the single hose and gauge because it introduces moisture in the system every time you hook it up since you can’t really bleed the hose before putting it on the vehicle.





@Twisted Steel Performance there is a Johnstone Supply and United Refrigeration close to each other in Spartenburg. My first stop would be Johnstone. They are both close to Hearons Circle off of 85 Business. If you decide to go get something at one of those parts houses let me know and I’ll give you the info to get our company discount.

 

[MrMarty51]

Thats a lotta infurmashun to wrappa head around.