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meatpimp
May 15, 2004

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Hi thread. It's been over 2 years since I checked the air on the Escalade with the dual system. The air is working fine, but I think it's time to check the pressures. From what was said in the previous thread last time I brought it up, the lines going all the way to the back allow for some leakage over time?

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meatpimp
May 15, 2004

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Thelonious posted:

I'd call it good if everything seems to be working fine. Throwing gauges on without good reason is a good way to waste a small bit of refrigerant or introduce contaminants needlessly.

But I'm just a dumb residential HVAC monkey who can get a pretty accurate idea of system performance just by checking some assorted temperature readings. Probably not as simple on a vehicle.

Is it something you can talk me through on my home system? It's an almost 20 year old Trane A/C unit that I'm hoping to get one more year out of. I last had it checked about 4 years ago. I just cross my fingers every time it runs.

meatpimp
May 15, 2004

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Reposting this from the chat thread because it applies here, but I'll probably make Motronic roll his eyes due to my improper chemical handling.

quote:

Trip report: Chemical burns, but ice cold air conditioning.

2000 Toyota Avalon -- I've had it a couple years, 166k miles and smoked in like it was making brisket. I got rid of all the odors with and ozone generator right after I got it, but the AC was always tepid. Gauges said the charge was fine, I just dealt with it.

But this year, it started cooling better, and I noticed drainage from the condensate drain for the first time. I started to think that there may be some poo poo on the evaporator, so I squirted some coil cleaner up the drain and let it sit for a few minutes. Then I drove it and had the compressor run for about 45 minutes to get as much of the coil cleaner off as possible.

The result? 49* air out of the center vents with recirculating off and 38* air out of the center vents with recirculating on... and an 86* ambient temperature.

The only bad part was that I missed a dollop of coil cleaner on my forearm when I washed my hands, and when I looked down an hour later, the hair was gone and the skin was red where it was. Washed it off and dumped some baking soda on it. Good enough for triage.

The wounds healed fine and the car was ice cold today at 91* ambient.

meatpimp
May 15, 2004

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Motronic posted:

Yeah, sorry should have specified that. This is "the inside of the shop is 90" kind of conditions, and absolutely let the cabin get down to temp first. You're just trying to see how it's working when it's at "normal" operating conditions, not how well it struggles itself down from bring rocket hot.

If it's over 90 you probably need to throw a big shop fan in front of the condenser.

In my poking around, automotive AC doesn't really seem to have the same concept of delta T as fixed systems (very roughly - 20 degree differential between intake and output at normalish room temperatures), so I'm actually having trouble finding a chart. This is probably why I've always known it as "be somewhere like 38-48 if the outside temps aren't extreme" as the rule of thumb. Was going to try to get that more specific for the thread, but I'm coming up short at the moment.

I've never seen numbers like that, and I've always assumed it was because there were too many variables -- outside temp, outside humidity, air latency across the coils dependent on fan speed, cfm of the system, etc...

meatpimp
May 15, 2004

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Motronic posted:

There are absolutely numbers for fixed systems,

I know, I've been watching my delta T go down to about 13* at home with a 20 year old unit.

Yes, I'm HVAC shopping.

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meatpimp
May 15, 2004

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everdave posted:

I hate to say this, I have this thread, I have the gauges...and I am just scared to crack open this Celsior (basically LS400) and have a go at it...this fear that I am going to screw it up or ruin the compressor or whatever...


IOwnCalculus posted:

I would imagine that the compressor is the same as US-market LS400s and is probably common as hell.

At any rate you'd have to try pretty hard to shove enough liquid in there to actually hurt the compressor.

Yup. Hook up the gauges and see what they say. Then refer to Motronic's OP, because it's got all the info you need to do it correctly.

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