dwynne

I agree! If this was a chilled air system, then this might help - but this is "freon". As soon as it hits the compressor it is going to be red hot again.

Tigster said:

and this just not correct. The cold pipe is the suction pipe that is LEAVING the cabin of the car - the gold color pipe below this one (that will be VERY hot) is the compressed "freon" going INTO the cabin of the car.

http://www.energyquest.ca.gov/how_it...nditioner.html

http://www.edmunds.com/ownership/tec...9/article.html

are just a couple of the many places that explain how the A/C works - but it does not push cold air into the car at all.

Someone would need to do a proper before and after test to see if there were SOME benefit to this at all. I suppose a cooler temp imput to the compressor might make it work a little better but it is not going to be any sort of "dramatic" cool down of a car that was not cooling correctly to start with. You CAN effect a cooler system by spraying the condenser in the front of the car with cold water. This provides a better heat exchange with the hot outside air and will then remove more heat from the "freon".

Dennis

Nubo

Despite my skepticism there were enough testimonials to make me try it. For what it's worth I used a roll of "Frost King" hot/cold pipe wrap that I picked up at home depot

http://plumbing.gillroys.com/Plumbin...e-s420280.html

Due to the adhesive, a spiral wrap of the pipe is impractical; I just ran a couple of overlapping lengthwise strips and the obligatory zip ties...

More importantly, there may be some new info about programming the amplifier

https://www.rx8club.com/series-i-trouble-shooting-95/new-ac-fix-dealers-66922/

I did the wrap last night and will do the reprogram before I leave work. So if it's magically better I'll have no idea how much improvement to attribute to either action. Oh well... I wouldn't want to break the spell

pcimino

I took temperature readings on my vent, with all settings the same, over three days before doing the pipe wrap, and then after. Short answer is there was no difference. Most of the readings I took on the way to work, pre-sunrise, so no radiant heating, just ambient temperature to deal with.

The interesting thing, is that regardless of the morning readings at 77 degrees or the afternoon readings in full sun at 90 degrees, the vent always cooled to a range of 54 to 56 degrees F. This suggests an artificial limit in the system.

As an engineer, I'm pretty sure the pipe wrap is not a placebo. But I did not encounter conditions where the AC only cooled to 65. I probably needed a 110 100% humid day to test with.

I know one time I took my wife for a ride and the AC started blowing warm air and she thought that was ridiculous. It could have been cycling off to make sure the exchanger didn't freeze up or something. But that was an unusual occurrence, rather than normal behavior.

TeamRX8

iTrader: (25)

as an engineer then you should go do some basic research on refrigeration which will confirm your reading results. Kind of funny that you tquestion the conclusion of the actual results

I've only ever seen an issue when the car is not moving fast i.e. not getting good airflow into the condensor, IMO the condensor may not be sufficiently sized to handle low air flow conditions. If this is the case the freon gas will not condense into liquid form, which would result in the system blowing warm if there is gas rather than liquid at the expansion valve. It wouldn't matter if the compressor was running all the time or if the frosty pipe was insulated or not if that's the case.

there's a reason the "frosty pipe" between the evaporator and the compressor does not need to be insulated, just as there is a reason that the compressor cycles on and off, it's all related to the basic fundamental design of how a gas/liquid refrigeration system operates. I am engineer too, having been involved with industrial refrigeration systems. The only time we ever insulate the frosty return pipe is when we don't want condensate forming and dripping down off of it onto whatever is below it. If the whole basis for this kooky thread were true for a small automotive AC system can you imagine the energy savings a large industrial plant would gain by insulating the frosty return pipe?

The truth is in your results.

this entire thread is one of the greatest exercises in ignorance that I've ever seen

pcimino

I agree, the proof is in the results. Which is why I ran the test, because I was tired of everyone writing conjecture.

The reason I was surprised is that most AC systems I'm familiar with don't reside next to a hot engine block. My "theory" was the close proximity to the engine meant the system could be soaking up unnecessary heat. Even the return pipe should be at a much lower temperature than the block.

My experiment disproved my theory. Which just goes to show a little science could have stopped this whole thread in its tracks a LONG time ago.
:D

Chrisbert

Home AC is a considerably different beast. The refrigerant in the system is designed to stay colder longer because the compressor is often 100-200' of pipe away from the coils. The refrigerant in car systems is, thanks to our government protecting us from ourselves, quite crappy.

Most home systems I've seen wrap only the supply line. The return line is usually secured to the outside of the wrapped supply line.

If your system is in the attic, they will wrap the condensate line to keep it from dripping due to the cold water inside condensing on the outside from the attic heat.

dwynne

I agree, but logic has no place when it makes them feel better

You should also go read the "Reprogramming the AC" thread - where you hold down some buttons and lose control over your AC. It will now automatically go to recirculate any time it is hot out and you have the control on full cool and in dash vent mode. No duh, on a 100 degree day that would be better than trying to recool the 100 degree air outside the car. But once it is explained that you can do this yourself using the fresh/recirculate button folks are STILL doing the "program" and declaring how much cooler they feel

Dennis

pcimino

How about we sell a placebo button on EBay? A bright blue button labelled "Sooper Cold" and instruct them to glue it onto the recirc button. Could probably get $5 each.

vrpirata

I haven't try this yet, but at first I though it was just a placebo.

But actually, by wrapping the line that goes from the Evaporator to the Compressor, the compressor will convert the gas to a slighly-colder-than-before liquid, adding efficiency to the system I guess. Then the Condenser would be able to do a more effective job of bringing the hot liquid to ambient tempeture.

The air comming out of the A/C system should be tempeture regulated; actually there is a "Evaporator tempeture sensor" inside the A/C unit. So I don't think the A/C is going to be any colder with this modification. However, I think wrapping that pipe would increase A/C efficiency, and therefore, reaching the desire tempeture faster, with less work to do and less load to the engine.

A good reference about refrigiration:
http://home.howstuffworks.com/refrigerator4.htm

dwynne

Given the length of the exposed pipe and the velocity of the "Freon" travelling through it, I would have a hard time thinking it will pick up much, if any heat from the engine.

Dennis

Nubo

Are you saying that it's not possible that some RX-8 compressors aren't cycing off prematurely? Ive sat and felt the output as the compressor cycles on and off. The temperature of the output air cycled markedly along with it. I understand the concern over the evaporator coils icing but during this test the temperature of the output air gave no indication of icing being imminent -- it wasn't that cold. Isn't it possible that system can be too conservative with the compressor duty cycle?

Chrisbert

Not sure, but I think that the refrigerant that leaves the compressor will be hotter than that returning, even before the wrap. Compressing the gas heats it up tremendously. The expansion of that same gas causes it be cold.

Nubo

I'll take the heat for insulating my frosty pipe because I have a general understanding of the principles and agree the potential for meaningful amounts of heat entering there is tiny.

But, I HAVE gotten a distinct and unmistakeable improvement after having done the reprogram procedure (well, yeah at the same time as the FP insulation job). Yes, I understand how/why recirculate benefits. I used it all the time BEFORE the reprogram. This procedure did something else that resulted in improved cooling. No, I don't have thermometer readings but when you go from a car that always reminds you that the AC is barely there, to one in which you're perfectly cool, subjective evidence is enough imo. Yesterday it was 95F and full sun on the way home and it was perfectly cool in the cabin with fan set to 3. And it didn't take long to get there. This was never even close to being the case before. Prior to the reprogram that ride would have been spent with fan roaring away on 4, with recirculate and would just have begun being tolerable right about when I was pulling into my driveway. Well, maybe I was hip-mo-tized by the flashing defrost light but hey, I'll take it.

Since the unit is "programmable" and we do not have definitive specs, isn't it possible that a reprogram could be making changes or clearing a condition other than what is described in the brief procedure?

I think it's significant that there is a widespread dissatisfaction with the AC in this car -- among people who are not naive and have driven enough vehicles to have a basis for comparison. And, not all vehicles seem to be affected. To me this rules out any fundamental design flaw in terms of specs. That is, condenser is adequate, compressor is adequate, etc. The answer lies in finding what is different between vehicles. Given the complexity of the control systems in the car I think it is logical that the control logic could be the issue.

salituro64

And that reprogramming would be....

Blue87Sport

The reprogramming is described here:
https://www.rx8club.com/showpost.php...54&postcount=8

There may be multiple ways/levels of reprogramming. It sounds like its still under investigation...

salituro64

Thanks

bxb40

From my experience, the air coming out the vent is not significantly colder (maybe is the same? no need to measure). But the last two days humidity was 100% and so was the temp in NJ (105F). Temp inside car was OK, I was comfortable after the car was in the sun the whole day (open parking at work). Before the updated AMP and pipe insulation, anything topping 95F would not be cooling down enough for me to feel comfortable (going once at the shore was a sweaty yucky experience). So all this theory is great, but I only care of how the car feels, not why and what changes by which law of physics... By intuition, a system that has as only purpose removal of heat cannot benefit from extra heat input. Heat removed from the air forced inside the car = heat exchanged with the outside air by the AC radiator in front. If that pipe picks up heat from the engine bay, the radiator has to work harder. This is a law of physics too; energy conservation. So, maybe it does not pick too much heat - but what if it does? Can we check? No. And that pipe will burn your hand after driving the car - at least in my case since due to the MS strut bar, the engine cover is gone (maybe that one made a difference? no idea).
Geesh... for few bucks, is worth trying, as all agree that while it might not help, it definately does not hurt anything.
Don't we have real issues to solve on this car? Insulating or not 3 ft of pipe should be at the bottom of the pile with problems...
I only post so people do not get scared reading all the contrary theories and not even try to do it. Laws of physics or not.... just try, one never know (wasn't the Earth flat at some point? how come is round now? theory changes all the time - results don't).

Tigster

I never thought the thread I started would get this long with alot of lengthy explinations of why it won't work. I can say I have has this done for almost 8 months and I notice a difference. Call it a placebo effect if you must, but if you dont agree save your $5 worth of supplies and go to McDonalds.

wedge357

I just thought about it, but my 05 shinka does not automatically revert to recirc mode when I turn the fan to full blast. So I decided to experiment to see if the programming works for 05 cars, and it did! Now I don't have to remember to make sure its on recirc when I need cool air ASAP, it does it for me automatically. Good thread...

salituro64

Is this programming feature a factor of the flash or the electronics of the AC unit? Meaning if the electronic feature was not in the car for earlier models, it won't work.

Nubo

My understanding is it requires the new version of the AC amplifier, so your vehicle either has to fall outside of the VIN range for the TSB, or you need to get the improved amplifier under the TSB. For a list of TSBs, go here

http://www.finishlineperformance.com...ins_index.html

RetroRotor79

I also noticed a significant improvement in the A/C after I reprogrammed it to recirculate automatically when set on maximum. I've tried manually selecting recirculate before and didn't perceive it to work as well as it does now. Either way, it works well enough now to be acceptable.

derwankel

I agree retro ... there is a significant improvement (no placebo) in the temp of the air exiting the vents with this configuration. It has been in the mid to upper 90s here in Atlanta with plenty of humidity and there is no doubt my A/C (10/03 build) is much improved since I went through this procedure.

Not only is it acceptable, it's comfortable.

salituro64

[QUOTE=Nubo]My understanding is it requires the new version of the AC amplifier, so your vehicle either has to fall outside of the VIN range for the TSB, or you need to get the improved amplifier under the TSB. For a list of TSBs, go here

TSB was acknowldged by the dealer two weeks ago and the new AC amplifer was ordered. Thanks for the clarification.

beachdog

When an evaporator ices, the output air temp rises because the air cannot flow through. The ice blocks the airways. Icing is usually caused by refrigerant leaks, not excessive compressor run times (actually they can be connected in an automatic climate control but not in a manual like the 8.)