u/bimmeister_flex

Some parts of north america are in a heatwave now, and I hope everyone's staying cool and hydrated when possible... seen some of these attic psych readings...

Was on a hot rooftop an hour ago but it's nowhere that hot where I am, so I can't imagine! Anyway, as a break from the usual programming (mods remove if not appropriate), I came across this little history of refrigeration technology from the ASME! There are some interesting old patent drawings!

https://www.asme.org/getmedia/cb9bea09-6d23-425e-bfe5-5f6d786919fb/274-perkins-vapor-compression-cycle-for-refrigeration.pdf

Cool (haha) to think that the first vapor-compression refrigeration machine was built all the way back in 1834, and the technology had been more or less invented several decades before! Have a great day and weekend!

Before I get all the haterade, I'm a new apprentice. Had a call last week on a 10 ton system (weathermaker) recently where it apparently had a stuck TXV a few years back, and had A/C Renew put into it (previous tech left a note on the unit), and we confirmed this with the building owner. I haven't had to fix any major leaks yet, but my journeyman today was having a hell of a time trying to figure out if there was a leak in the system (pressure was low), even with his DR58. We don't have an ultrasonic tool, so nitrogen pressure leak testing is out of the question. He wants to jump straight to UV dye, but... won't that mess with our equipment? Asked another guy at work and he said that some leak sealers don't have dye in them, and that it's something we can try, but that was overridden, because apparently leak sealer can mess with a/c renew that's in the system? The system also has a reversing valve, and in my book/classroom studies I recall that they can sometimes bypass and make it seem like there's a leak in the coils when there isn't? I told him that we should manually switch modes (the heating seems to work) and verify the valve works anyway, it's a loud place (small industrial area) and we couldn't hear a whooshing noise but I figure there has to be some way of testing the valve. It does blow heat fine, which is why I think it's something with the valve or some restriction, rather than a big leak or something.

idk. The thing is, my journeyman knows his stuff and has been really helpful to me but I think we're going about this the wrong way. It's a 10 ton unit, I just don't understand why we shouldn't do a nitrogen pressure test and vacuum decay test and buy or borrow an ultrasonic from the supply house. What would you guys do? If the answer is well leak sealer can cause problems... well, if the UV finds a leak, then the system already is infected with UV dye and we have to yank out all the coils anyway. Also, I think the customer will be livid if we add UV, replace the coils, and then the issue ends up being a fucking valve. And as title of my post, can leak sealer interact negatively with a/c renew? I know some leak sealers have UV dye in them, but some don't, and I am wondering why we don't just use one that doesn't. Just don't know if it would gunk up with the renew that's in the system.

sorry if this isn't an appropriate question here. The one time I asked a question on the HVAC sub I got banned lol hence my flair. need to show your certs to post there and yea I'm not posting my certs online. And yes I'm dumb and new to the trade. Thanks! Also I really don't think I'm going to last long in this field haha. Need the money for now but it's ending up being really difficult especially with some of these commercial systems.

I'm newly certified, and keep experiencing and learning a lot of things and am bugging my partner wayyyy too much already, so I have another question for here. Someone in our fleet uses core depressors especially when working on commercial systems that might be overcharged. Seems smart, less of a way to freeze your fingers if a low loss fitting jiggles loose or you fumble attaching it to the high pressure side. I'm going to buy some myself. Are these popular where you work?

Also, I've been thinking more about the reasoning behind things, rather than the procedures I've memorized, and am wondering why the center/charging hose doesn't use one-way check valves. We'd never want gas to enter the charging cylinder, right? So why aren't there two one-way valves on this hose, rather than bi-directional Schrader valves?

Few "boom" type events in the past, but the compressor seems to be running fine. Run cap is fine (one year old, and tested capacitance with a DMM), subcooling and superheat are right on target (subcooling is 12 F, I forget what the superheat was but it also checked out), coils are freshly cleaned, drain line clean, blower clean and running smooth, vents vacuumed and clean, duct work externally looks fine upon cursory inspection (no collapsed vents or leaking sounds I could hear (didn't use one of those hearing devices though), air flow inside is fine with hand and anemometer), new air filter installed. Only thing that stands out is that TXV is sometimes wet, sometimes dry, some strange intermittent behavior. Sensible split is crap, about 12-14 F, with no improvement over time. Not much change in RH/latent, either. Similar system is around 20-25 F and pulls down temps and RH very rapidly. Busted one won't pull down sensible temp at all (bit of wet bulb though, measured with a fieldpiece), even after 2 hours. Suction line is warm (around 68 F with a thermocouple), but the liquid line is fine at 100 F on a hot day. I'm confused as to how the suction line can be warm like that but the bulb is wet sometimes.

Anyway, before replacing the TXV or compressor, any thoughts on zerol ice/ac renew? I'm only recently licensed, my journeyman wants me to figure this out, but I'm already stumped. Customer is fine with a more temporary fix as they don't expect many more years out of the system. As I said before, refrigerant levels are fine (because subcooling and superheat are fine), so they don't need any more of that. It's R-410A by the way, not R-22. I'd think maybe the refrigerant got fouled/contaminated during one of those audible events in the past (maybe liquid slugging the compressor?), but the subcooling and superheat temps are fine so that's all that matters I think.

Sorry if this question isn't appropriate for here. tbh this stuff is just really confusing, it's my first week on the job and I'm already floundering.

tl;dr customer is looking for something quicker and less expensive than replacing a TXV and/or compressor. Is A/C renew (zerol ice) legit for a short term (months to a year) fix?

Hello everyone! Rather new to detailing.

When I open the door on my car, there is a 1-1.5in semi-hard plastic strip that goes around the entire door on the car side, and then there's a 0.5in soft squeezable weather stripping after that, which mates with a similar type of weather stripping on the door itself.

I've neglected any sort of detailing or work on this aspect of my car. Been many years, and what were once black/dark grey are now light grey/whitish looking.

I picked up Sil-Glyde (which is like a thick, slippery silicone gel), and Meguiars Mirror Glaze Vinyl & Rubber Cleaner (which is a spray with a few different chemicals listed on it), and microfibre cloth applicators.

Both of these products say they refresh rubber and are safe on rubber, and are slippery (this is good, I like the "wet black/shine" look).

Is one better than the other? On a test section, what I did was first use Sil-Glyde, and then after that sprayed the Meguiars onto a different part of the applicator pad and then rub that on top of the sil-glyded surface. This returned the part of the hard thicker part to black/dark grey. I'm not sure what to do about the weather stripping ,should I use this same method?

Also, I can't find out whether or not these products are supposed to be used together, i.e. are they miscible or not or will they combine to form some gloup/bad compound. Should I just use one or the other, instead of using both?

I also have a sunroof that doenst open without going ka-CHUNK over and over again because it's also dried out like this or something, so I was going to use water to rinse out any gunk, followed by silicone spray, followed by sil-glyde, but NOT using the mcguiars vinyl and rubber. figure that the silglyde I want it to be as slippery as possible up there for smooth operation, and you never see the inside tracks anyway. Maybe I should use white lithium grease here? I'm afraid that will attract too much dust/pollen, though.

Thoughts? Thanks so much in advance, it's my first time posting here and I'm also really dumb at this stuff and also have a tendency to overthink things. I just don't want to ruin my car's rubbers, even though my car is a piece of crap but I love her lol, I just didnt know how to take care of these things properly when I first purchased her (I was young and dumb(er)).

Planning on going to R1 with some friends, have not been to this type of arcade in a long time. We want to level up cars in some racing games like initial D and wangan MT. I'm used to arcades where it's ~0.50$ a play, and it seems like this is going to be a lot higher than what I'm used to if I just play for single credits.

but there is some membership card, and an app, and timed play for racing games? someone on here posted a bit about sitting at two machines loading credits? Is there some guide on this? I'm also not really into apps (old and slow phone), do I need the app or can I just get these physical membership cards? it seems like I need to buy 2 black membership cards for myself and then simultaneously keep loading them every 90 seconds on two machines to stack credits within one hour?

Thanks... I just don't want to be paying over 1.00$ per play, we'll never be able to level up our cars without paying a small fortune at that rate. can we share these cards or do each of us need to buy 2 black membership cards? not trying to abuse the system but racing games are kind of designed for the asian market expecting players to be there for hours at a time not spending that much money per race/single play. of course if there are other people waiting and put their coin/cards up, we will get up and let them play. we're planning on going during off-hours, so there should be no one there really anyway.