A question for hvac gurus

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A question for hvac gurus

Postby steve mortillaro » Fri Mar 17, 2017 8:52 am

I refuse to go another summer w/o a/c in my old Trooper 2.8 v6. About 3 or 4 years ago I removed the a/c compressor when I lived in Cape Cod and didn't really need it. I plugged the ports in the engine bay and electrical taped the crap out of them. I still have my old compressor and everything I need to put it back. I plan on replacing the drier and exp. valve, seals and having a great local shop fab some new hoses for me. I plan on going with duracool or envirosafe r-12. My question is can I use my old compressor which was working fine and do I have to pull a vacuum on the system when recharging. And any other thoughts on the subject would help. Thanks
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Re: A question for hvac gurus

Postby gwana66 » Fri Mar 17, 2017 3:09 pm

I am not a guru, but I know enough to be dangerous.

I say this without malice. If you don't know, you probably shouldn't try. There are a hundred ways this could go wrong, and only one way it will go right.

You will need to flush and remove every trace of old oil and sludge from the remaining components, including the condenser and evaporator. They have been open to air and any moisture in the system will kill it.
You will need the right amount and type of oil - mineral, PAG, etc. that is compatible with your refrigerant and compressor.
You have to get all oil out of the compressor and other components so you can put the correct amount back in. It's everywhere now.
Your orifice tube will need to be the right type for that refrigerant.
The seals in the compressor are lubricated by the oil moving through the system, so its condition now is unknown.
You will need a vacuum pump before you charge to remove all air and check for leaks.
You will need a set of gauges for whatever refrigerant you use, and know what a good high/low charge is for your refrigerant.
If you fill the system with anything but R-134a and have a problem, no shop will touch it.
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Re: A question for hvac gurus

Postby DSUZU » Sat Mar 18, 2017 4:35 pm

What did you "plug" the ports with? The oil isn't all that critical. There has been so much mixing and matching donne that who knows what is in any system. Originally, it was said that R134A wasn't compatible with R-12's lubricants. When this crap all started, our fleet worked with Ford Motor Company on A/C refrigerant compatibility. We tested with about 12 police cars (heavy, extreme use). "Conversions" ranged from suck out the 12 and put in R14A to complete component replacement and "special" compressors. No discernable differences. No failed compressors, no clogging.
Myself, on my Spacecab pickup, after running God knows how long without A/C (previous owner), I recharged the R-12 system R-134A. The only "mod" was a larger condenser from a Rodeo (thicker) because I had a donor vehicle. After running a while (months) it developed a leak at it's pressure switch (only about 25 years old). After that I recharged with Duracool. Then a hose leaked (that 25 year old thing again). Ran R-134A after that. Currently, it has another leak, and I will shortly (Florida summer coming) be checking and another R-134A refill.
When you (or whoever) evacuate the system, all moisture is removed (if vacuumed to the 30" mark). Usually, you see if it will hold vacuum for 30 minutes. Given that your system has gone this long, flushing might be a good idea. Dennis
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Re: A question for hvac gurus

Postby Mike 17264 » Sat Mar 18, 2017 11:13 pm

The most important thing is a clean dry system. I recommend disassembling the system and flushing with compressed dry nitrogen, NOT compressed air due to moisture. After that reassemble system and then install the new drier and TXV. Since the system has been open for a few years you should change the oil in the compressor, refilling it with new mineral oil. Next pressurize the system to about 120 psi with nitrogen and leak test all your connections with a soap bubble solution. At this time you can also do a standing pressure test for a few hours to ensure there are no leaks. Blow off the nitrogen and evacuate the both the hi and low sides of the system with a vacuum pump ideally to a 500 micron vacuum. Now the system can be recharged. You can use R 134a I have seen it done and it will work in an automotive application such as this. There are a few direct drop in refrigerants on the market. I have been using R 414b (Hot Shot) for 20 years and it works great. Operating pressures are very similar to R 12 and has been very reliable, however it is a blend which R 22 is part of the make up. R 22 has not been manufactured since 2015 and is getting more expensive every day along with R 414b. There is a new Hot Shot 2 (R 417c) that is the replacement for Hot Shot. It too is a direct drop in and has been working very well. If you have a commercial refrigeration service company in your area, they will have access to these refrigerants more so than a garage.
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Re: A question for hvac gurus

Postby steve mortillaro » Wed Mar 22, 2017 9:12 am

DSUZU wrote:What did you "plug" the ports with? The oil isn't all that critical. There has been so much mixing and matching donne that who knows what is in any system. Originally, it was said that R134A wasn't compatible with R-12's lubricants. When this crap all started, our fleet worked with Ford Motor Company on A/C refrigerant compatibility. We tested with about 12 police cars (heavy, extreme use). "Conversions" ranged from suck out the 12 and put in R14A to complete component replacement and "special" compressors. No discernable differences. No failed compressors, no clogging.
Myself, on my Spacecab pickup, after running God knows how long without A/C (previous owner), I recharged the R-12 system R-134A. The only "mod" was a larger condenser from a Rodeo (thicker) because I had a donor vehicle. After running a while (months) it developed a leak at it's pressure switch (only about 25 years old). After that I recharged with Duracool. Then a hose leaked (that 25 year old thing again). Ran R-134A after that. Currently, it has another leak, and I will shortly (Florida summer coming) be checking and another R-134A refill.
When you (or whoever) evacuate the system, all moisture is removed (if vacuumed to the 30" mark). Usually, you see if it will hold vacuum for 30 minutes. Given that your system has gone this long, flushing might be a good idea. Dennis


I plugged the ports with lg-size rubber caps that are used mainly for blocking off ports to a carb/ throttle body. I pressure fit these in upside-down into the ports immediately after removing the lines/hoses going to the compressor and then taped them up real good to keep them there in order to keep contaminants out of the system. Basically removed the compressor with its lines and hoses attached.
The main reason for my questions is I was reading on the internet (we all know that everything on the internet is a FACT!) that one of the butane-based refrigerants (It was either duracool or envirosafe) claimed that all you had to do was fill the system to like a third of it'[s capacity and that evacuating the system was not necessary...
Oh, and the a/c has always been r-12 from day one. The p.o. of this truck (actually belonged to the old vet across the street from my parent's house who bought this trooper- a manual xs and another automatic ls, both brand new within about 2 weeks of each other in 1990 when I was still living with the folks) had the compressor changed and the system refilled with r-12 right before it came to me in 2005. I had it recharged again with r-12 in about 2009 for like $80.00!, and that only lasted one and a half summers in the hot humid gulf south. I moved to Cape cod in 2011 and didn't bother refilling it, eventually removing the compressor a couple of years later for no noticeable improvements whatsoever.

[b][/Thanks to all!b]
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Re: A question for hvac gurus

Postby Mike 17264 » Wed Mar 22, 2017 9:48 am

Air is considered non-condensable. All refrigerants no matter what type are condensable. Refrigerant has to be completely free from any non-condensables to operate properly. The basic refrigeration cycle depends on the refrigerant to condense and evaporate at design temperatures and pressures for proper heat transfer. Air in the system greatly affects efficiency and will lead to component failure. That is why a good deep evacuation (vacuum) prior to system charging is necessary. I really bothers me to see these commercials on tv showing the two guys sweating in the car so they stop at an auto parts store and grab the kit, charge it up and are happy and cool. They are skipping the evacuation process and will have problems later on. Another issue is leaks. All modern refrigerants are blends of several different types of refrigerant. If you have a leak the blends leak off at different rates, so your chemical make up will change.
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Re: A question for hvac gurus

Postby Ed Mc. » Wed Mar 22, 2017 2:54 pm

Another good reason to evacuate is that any moisture left in the sealed system will tend to form acids that will eat up the innards. Not a good thing.

Even a single-stage vacuum pump is better than nothing and there are plenty of 'em on ebay and Amazon for reasonable prices. If there are any automotive swap meets in the area, likely there's a decent vacuum pump and set of used refrigeration gauges for cheap.
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Re: A question for hvac gurus

Postby steve mortillaro » Wed Mar 22, 2017 4:51 pm

Thanks all! If I do this, I will evacuate and flush the system first, otherwise I will just pony up the dough and have a shop do it.
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Re: A question for hvac gurus

Postby Ed Mc. » Wed Mar 22, 2017 5:50 pm

steve mortillaro wrote:Thanks all! If I do this, I will evacuate and flush the system first, otherwise I will just pony up the dough and have a shop do it.


Amazon sells a flush kit for only $26.99 shipped:

https://www.amazon.com/dp/B06X9QSHM9?psc=1

$12.71 for a quart of the flushing solvent:

https://www.amazon.com/Johnsens-6545-6- ... op?ie=UTF8

I read a comment in the flushing solvent reviews that your local Autozone might have one of the flushing kits available as a rental, so you'd basically get it for free after returning it.

They also commented that the solvent was about twice as much in the store, as what it is on Amazon.
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Re: A question for hvac gurus

Postby steve mortillaro » Wed Mar 22, 2017 7:01 pm

Thanks Ed! So if I were to use this kit, would You reccomend that I vacuum pump the system after?
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Re: A question for hvac gurus

Postby Ed Mc. » Wed Mar 22, 2017 7:29 pm

steve mortillaro wrote:Thanks Ed! So if I were to use this kit, would You reccomend that I vacuum pump the system after?


Yeah, you have to; after the system is flushed clean, it still is open to the atmosphere and any air (and the moisture it may hold) must be evacuated. The other issue is that any moisture left in the system will freeze and there goes your A/C!

Check out my comment in this thread, there are links there for other A/C system service tools including a decently-priced vacuum pump:

viewtopic.php?f=15&t=102865&p=5249105&hilit=vacuum+pump#p5249105
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Re: A question for hvac gurus

Postby Mike 17264 » Wed Mar 22, 2017 7:49 pm

Harbor Freight has an ok selection of hvac tools that would be suitable for light duty use. They used to sell an air powered vacuum pump that was basically just a venturi. They are cheap but I would avoid this because they do not pull a deep enough vacuum. A single stage electric pump will work just fine for you. In fact on a small system like this, pulling a slower, longer evacuation is better for boiling out any moisture that may be in the system. Since your system has been out of service for a few years, I would let the pump run for a few hours to ensure it is clean and dry, especially if you opt to use a flushing agent.
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Re: A question for hvac gurus

Postby Ed Mc. » Wed Mar 22, 2017 8:05 pm

Roger that, it's what I did on the '98 Tracker a couple of years ago. My old refrigeration compressor doesn't pull down fast but if left on as you suggested, it does a serviceable job. I was reading the comments on the air-powered pump and yeah it sounds too marginal for HVAC use. The Tracker still has ice-cold A/C so I was really happy about that!
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Re: A question for hvac gurus

Postby EricJette » Wed Mar 22, 2017 9:57 pm

Duracool is compatable with your system. I'm running it in my 86 trooper and getting 38-40 F at the vent. Duracool sells a kit w/ adaptor, I suggest you also get a can of duraseal.
If you go to the main website and use the contact # , these folks are all about customer service It must be a Canadian thing. You'll probably be given a US distributor contact # near you and tell he guy what's up with your system and it's capacity. I'm sure they have what you'll need as far as oil and instal advice.

I had a shop replace o rings and do the evac & charge, they were really impressed how good it works in an old R-12 system. Fortunately I got 2 cans of duracool and one can of duraseal as it had blown out an o-ring at first try, but I had enough left for about a 3/4 charge so I'm getting really cold temps without even a full charge in the system.

My system unlike yours had always been intact and had been working a couple years before, thus the evac of old r-12 remnants prior to charge.

Anyway, that's my 2 cents worth. Good luck with your A/C . Oh, I think the price of the 2 can kit plus a can of duraseal + shipping came to $85 or so. Which is about the price of one can of R-12a last time I got any.
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Re: A question for hvac gurus

Postby steve mortillaro » Thu Mar 23, 2017 9:44 am

Thanks to all- so helpful!
I will attempt when I get the chance. I think I'll also get a seal kit when I get a drier and expansion valve. Speaking of expansion valve, anybody know it's precise location? I assume that it's up under the dash/ glove box area coming out of the evaporator... also since the compressor has been removed and uncorked (it wasn't frozen up when I removed it) should I flush this too, or will that mess it up?
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Re: A question for hvac gurus

Postby steve mortillaro » Wed Apr 19, 2017 9:04 am

Bumping bumpity bump
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Re: A question for hvac gurus

Postby Ed Mc. » Wed Apr 19, 2017 2:23 pm

Attached is a diagram of the evaporator core, showing various components including the expansion valve.

I found some info at this site saying the compressor should not be flushed:

http://www.autoacsystems.com/_faqs/3tiplist.html

Here's a good video about draining and adding oil to your A/C compressor:

http://www.discountacparts.com/videos/a ... or-oil.asp

According to the video, the amount of oil should be stamped on the compressor. Or you should be able to find that value in a manual or by plugging the model # of the compressor into a search engine.

Edit: Here ya go! http://www.techchoiceparts.com/refriger ... ties/isuzu

HTH...............ed
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Re: A question for hvac gurus

Postby FE125 » Wed Apr 19, 2017 11:58 pm

I finally got serious about fixing my AC after years of pumping 2 or 3 cans of R-134 in every season and getting very little cooling for my effort. I got an ebay vac pump, some cheap gauges and a $19 sniffer on Amazon. All of these tools work very well to my surprise. My AC has been running on R-152 ( canned air duster) for two years now and it is colder than when new. As far as finding the leaks, invest in the sniffer. The dye/UV light and soap bubbles didn't help me. The vac pump will tell you you have a leak but won't help you find it. You need to pressurize the system to find leaks so whichever refrigerant you plan to use, buy extra. If the condenser is original, don't be surprised if it leaks, mine did. Also had a hole in the connector pipe that goes from the TXV out through the firewall. Couldn't get that part so I repaired it with Alumiweld. If you can get an evaporator at a good price, I would replace it. You won't believe how much dirt and debris you will find in there when you open up the evap box. It's a wonder any air could get through mine at all. My truck doesn't have a cabin air filter so the evap core becomes the filter. I was shocked at how much more air my blower pushed with a clean system. I sealed up all open holes around the cowl and glued bug screen to the bottom of the cowl vent grills to keep leaves from getting sucked in.
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Re: A question for hvac gurus

Postby steve mortillaro » Thu Apr 20, 2017 6:43 am

You guys are the bomb! Big Thanks! :bom:
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Re: A question for hvac gurus

Postby steve mortillaro » Sat May 06, 2017 8:28 am

Last night, cold air returned to the vents of my Trooper for the first time in 10 years!
Couple of ?s, though:
I flushed the system real good, added all new seals, installed a new drier and expansion valve. I also installed a new compressor, drained as much of the PAG out of it as I could (2 out of 3 oz) and there was some debris in there- tiny, black and not much. I put in 4 oz of Ester oil and drained it again, then added 4 oz of Ester for a total of 5 oz. oil. I pulled a vacuum for like 2 hours and the system held at about -29 in/hg for about an hour. I charged the system w/ r12a, using just under 12 oz. (which, according to Red Tek is the proper amount). I purged the charge hose then allowed the refrigerant to equalize the vacuum to both high and low sides. Then I only added at the low side with the system on. The compressor kicked on and drew the remnants of the first can and was not noisy at all. I closed everything off and repeated the process for the second can, but the compressor would not kick on. I went to the evaporator temp switch and as I was just touching the connection, the compressor kicked on again. I had to hold the connectors in a certain position and then the compressor would compress, but it was noisy. I finished adding the refrigerant. Shut everything down properly and removed my gauges. Took her for a test spin for about 5 miles at 60 mph and it blew really cold, except I kept hearing that themo switch at the evaporator clicking. When I got back home I popped the hood and now the compressor was no longer noisy when it would engage. Is it normal for a new compressor to be noisy when it would engage, then quiet down after everything gets circulated real good? (maybe its the old idler pulley bearings- I spun them by hand and they were fine but that's not much of a load) The other question is I don't recall hearing the thermo switch in the evap clicking last time the a/c worked (10 years ago)- is that normal or could it be the switch is on its way out?

Thanks again all, to thos who have helped!
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Re: A question for hvac gurus

Postby steve mortillaro » Wed May 10, 2017 12:14 pm

After a few days, the compressor has really quieted down and it seems like less of a load when it is engaged. It still cycles every 10-15 seconds when I am cruising along, and I can hear the thermometer switch in the evaporator clicking. Seems too often. However, the air is ICY cold (haven't put a thermometer in the vent yet) but it's about as cold ac I've ever experienced. According to my discount manifold gauges, at idle the low side reads just under 40 psi and the high side about 145 psi. 145 seems low, but it is my understanding that HC refrigerants operate at lower pressure on the high side. My concern is that the thermo switch is gonna wear out, the compressor may suffer, or that the evap is getting too cold. Any thoughts about this would be appreciated.
Thanks!
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Re: A question for hvac gurus

Postby EricJette » Wed May 10, 2017 12:23 pm

Do you have it set on "normal" or "max"? This will make a difference in how often the compressor cycles.
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Re: A question for hvac gurus

Postby Mike 17264 » Wed May 10, 2017 12:39 pm

Your pressures are right on the money. When it gets warmer outside you will notice that your compressor will cycle off less often due to the increased load on the system. The switch will eventually wear out due to it's life cycle however that may hundreds of thousands of cycles. It is doing what it is designed to do so I really wouldn't worry about it until it fails if ever.
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Re: A question for hvac gurus

Postby steve mortillaro » Wed May 10, 2017 2:21 pm

Eric- yes this is on MAX rather than NORM. I never set the a/c on NORM, but now I will to see if it cycles less and maybe keep it there if it does the job. Thanks!

Mike- thanks for the reassurance on the pressures and a little better understanding of why it wants to cycle
Like it does.
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Re: A question for hvac gurus

Postby EricJette » Wed May 10, 2017 4:30 pm

Yeah, i think you will notice the compressor does not work as hard. Though it is still cold at the vents. I'm running duracool , a environmentally safe R12-a oil compatible substitute - Blows 38F at the vent on "normal" in my 86.
95% mech. restored 2dr. /2 seat / '86 Trooper w/ A/C , New 1mil over-bored 2.3L (2305cc)/ All OEM Johnny5ive-built custom "5zd1", w/ 2.6 valves &"Jerry cam" in the 2.3L head/ custom built 3-core radiator/ Exedy clutch & rebuilt msg-5 tranny/ 30/9.5/15's on snowflakes/superwinch manual hubs/fully rebuilt front end - KYB shocks w/ steering dampener & Calmini torsion bars/ 89RS leaf springs w/90mm shackles/custom wood interior paneling & bedlined flooring w /Calmini tri-Y header w/high-flow cat and muffler on 2.25" stainless pipe.

Desert Trooper;
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Shaolin school of Isuzu graduation day; "And now little trooper, when you can grab this socket wrench from my hand, it will be time to start your engine."
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EricJette
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