q45tech,a question for you

[qship96]

After extensive reading here and on other a/c forums.I am confused on the flushing process when replacing the compressor.You advise flushing the condensor & evap. - which I understand . the older r12 condensor was designed with large internal passages that could easily be flushed,yet I read the newer r134 condensers have tiny internal pathways that cant be flushed like the older ones and therefor flushing not advised?{what is proper for the 96q ?} Also I read not to flush expansion valve with the flush chemical when flushing evap-do you need to remove exp. valve when flushing evap? I am replacing original compressor that is still working and quiet,yet not efficient-I wonder,do I even need to be flushing in this case since old compressor hasnt grenaded and spit debris thru system?

[Q45tech]

Examine the inside of hard and flexlines for signs of black death debris.......long medical Qtips.

The flush agent we use is a HC that is a liquid at room temp but evaporate easily as it get warm forced thru via compressed air.

If you remove evaporator why not dissemble valve and clean carefully.

Getting as new performance after 7 years usually means new parts.

[Defiant]

I'd leave this part of the job to an AC shop, if not even the Infiniti dealer. Some things are just worth the money.

[maxnix]

I'd leave this part of the job to an AC shop, if not even the Infiniti dealer. Some things are just worth the money.

Absolutely I would search for the best automotive AC shop and take along a copy of hte FSM and some crib notes to check if they get the correct information form all-data or just some-data.

Bring your hardware from Joe knowing you can return what you don't open.
Modified by maxnix at 8:41 AM 4/8/2007

[DrewQ45]

I recently went through replacing compressor and converting from R12-R134. When pricing the flush, 3 different shops stated that there they do not flush the evaporator because it sits on the low pressure side of the system the flushing pressure is too high for it.

In your case, you're not switching to another type of refrigerant so you have less work. Basically your only reason for flushing at this point would be to clean out all the oil. Since you have no idea how much oil is in the system and flushing would allow you to start from scratch. Q uses 8oz which you would add to the compressor's suction side (labeled "Suc") while turning.

Be sure to change o-rings and the drier as compressor replacement opens it up to air and the dessicant becomes saturated with moisture.

[Q45tech]

Just shows you the ignorance of some shops as with the proper equipment you can set the flush pressure to anything from zero +1 psi to 200 psi.

Anyway the lowest pressure in the system is 28 psi which is 10 times the amount necessary to slowly flush the system.

You flush each component individually with it's nominal pressure as appropriate.

The reason you flush is to remove the black death [bits of compressor seals - orings and the inside of flex hoses and particles from dryer that start migrating around from day one in a system].

If you find black death you must REPLACE any flex hoses and compressor.

[DrewQ45]

Just shows you the ignorance of some shops as with the proper equipment you can set the flush pressure to anything from zero +1 psi to 200 psi.

Anyway the lowest pressure in the system is 28 psi which is 10 times the amount necessary to slowly flush the system.

You flush each component individually with it's nominal pressure as appropriate.

The reason you flush is to remove the black death [bits of compressor seals - orings and the inside of flex hoses and particles from dryer that start migrating around from day one in a system].

If you find black death you must REPLACE any flex hoses and compressor.

Yeah, I think what they were really saying is that it's too much work. They didn't want to remove the expansion valve etc. I don't think he has to worry about black death since the compressor is still okay. Flushing also allows you to start from scratch with respect to the all important oil amount plus brings some peace of mind. If not flushing the evap, keep in mind that around 20% of oil resides in it. Most shops will tell you that as long as you get 80% of the oil out, you're okay. (with respect to mixing imcompatible oils)

http://www.aircondition.com/te...h-FAQ

"Question: Should the evaporator be flushed?" "Answer: Most would say yes, but some would argue that it's not worth the extra effort for two reasons. Flush solvents can be very difficult to remove from some evaporators. Sometimes the risk of not being able to remove the solvent outweighs the benefit of flushing that component. Secondly, some would point out that evaporators stay fairly clean because any dirt floating around the system is captured first by the receiver drier, then by the inlet screen of the expansion valve. In the case of an orifice tube system, most debris would be caught by the orifice tube screens before it could reach the evaporator. While this is mostly true, systems that use the block style expansion valves have no inlet screen, and dirt from a ruptured receiver drier could find its way into the evaporator. Also, oil likes to accumulate in low-lying areas of the evaporator. If your goal of flushing is to remove dirty oil, you'll have plenty of it in your evaporator."

[qship96]

car is going to a shop that I need to research and interview{and possibly watch} the process to be sure it is done the way I want it to be.The dealer is out,since I didnt purchase parts from them{they wanted 950 for the compressor part-they tack on 20% to retail prices of parts}. I will not be removing the evaporator,and will only get the evap flushed if it can be done while in place{ not sure about this as I hear evap valve cant be flushed with solvent? } I will flush condenser if I can determine the 94-96q condenser is the same as the older 90-93 condenser that can be effectivly flushed{according to the a/c forums,the newer r134 condensers are different from older condensers{r12} and have different construction with tiny passages that cant be effectivly flushed like the old ones and flush is not recommended} Otherwise the plan is to evac.remove and drain old comp.fill new comp. with same amount of new oil that i removed from old comp. +the amount of old oil recovered from evacuation + 0.2 oz. for the new drier,install new comp. and drier,then vacuum 30 minutes and recharge 1.76 lb of new r134.As you can see I still have some research to do in order to determine if/what to flush.

[maxnix]

The early R12 condensers and evaporators are different from the later R134a ones. Check the part numbers, including the compressor.

I don't understand the concern of solvents not being fully removed after a flush unless they are the wrong solvents initially.

[DrewQ45]

Add a bit more than you drain out since draining doesn't remove all the oil.

Not sure about not being able to flush your condenser, but if you do, that changes the oil amount...so does changing the dryer...they both contain oil. You'd want to add like 6oz at that point, the rest being left in the evap. Nissan would have used PAG or POE oil during production. Get some that has UV dye for leak detection. I used ester since it's compatible with any gas and I wasn't sure if I was going to stick with R134 or revert. Better not to mix oils if you can help it.

IMHO, you really don't need to flush at all... just add oil, drier and vacuum down. You'll be fine... I analyzed the whole process in depth because I was converting.

http://www.wikihow.com/Fix-Cars-Air-Conditioning

[Q45tech]

The fine print in the Calsonic compressor warranty says it's void if the system is not flushed and clean as brand new.

Always up to owner what risk they wish to take.

[qship96]

nowhere in the FSM,which is pretty detailed do they mention or suggest flushing evap/cond. during compressor or any other parts replacment.the main question I have asked has yet to be answered,which is-is the 94-96 condenser of a different internal construction than the 90-93,and is it one of the types that the experts on the a/c forums feel cannot be effectivly flushed due to the tiny internal passages as compared to the older r12 compressors which had a large fin/tube design? the compressor{brand new fron joe} includes a 7 oz supply of the correct oil which is drained and replaced with the exact same amount recovered from old comp. + .02 for new drier + amount recovered fron evac.

[qship96]

The early R12 condensers and evaporators are different from the later R134a ones. Check the part numbers, including the compressor.

I don't understand the concern of solvents not being fully removed after a flush unless they are the wrong solvents initially.

Brian,spend some time on the a/c forums,very knowledgable moderators who seem to feel the problem with trying to flush the newer design r134 condensers is that the entire internal core makeup is way different from older r12 condensers and that these passageways are so fine that trying to flush debris through them is ineffective and can create more problems than the potential ones you might be trying to avoid- no one here seems to be addressing this difference in the condenser designs and differences for the newer condensers.The newer condensers are no longer a tube/fin design,more like tiny internal honeycomb-look at the ac forums and help!

[DrewQ45]

the main question I have asked has yet to be answered,which is-is the 94-96 condenser of a different internal construction than the 90-93,and is it one of the types that the experts on the a/c forums feel cannot be effectivly flushed due to the tiny internal passages as compared to the older r12 compressors which had a large fin/tube design?

Since it's R134 you can be pretty sure the design is different. Which design was incorporated on 94-96? I could not tell you since I have neither the car nor the fsm for that year. You need to take it to an AC shop so they can eyeball the condenser if you can't tell by looking at it. Use the info below as a guide on what/not to flush....

How many different condensers are there, and which can be flushed?

R134a condensers have more fins/inch than R12 condensers and their fin diameters are smaller.( 6mm)

TUBE and FIN - Oldest industry standard, 3/8-inch diameter round tube condenser. Ok, for R12 but not recommended for R134a. This type of condenser is flushable.

6 mm PICCOLO multi-flow: smaller, lightweight and more efficient than 3/8-inch tube and fin and serpentine. Used in many domestic OE applications. This type of condenser is flushable.

SERPENTINE: All aluminum, more efficient than tube and fin, used on smaller imports where space is limited. This type of condenser is not easily flushed, replacement is recommended.

PARALLEL FLOW: all aluminum, this efficient design breaks up flow into tiny streams that give up heat more rapidly. This type of condenser is not flushable, replacement only!

PARALLEL FLOW with SUB Condenser. Oval tube multi-flow and sub-condenser stacked up. Refrigerant flows hrough the multi-flow into the drier (called a modulator) then continues as a liquid into the sub-condenser. This type of condenser is not flushable, replacement only!

http://www.aircoparts.com/1faq.htm

[qship96]

Drew,thanks for the post-it is one of the many I have read on the subject of condenser flushing,and the reason for my concerns .the fsm makes no mention of the type of condenser in the q,however there is NO talk of flushing either the evap or condenser mentioned in fsm when describing compressor replacement or any other service on the a/c system-makes me wonder if flushing is not the correct way to go.looking at the condenser gives no clue to its internal construction type as far as i can tell.It seems my quest for this information will help other board members when their time comes,as most seem as uninformed regarding this issue as I. Considering I what I spent for a brand new oem compressor,I want to be sure the process is effective and safe to maximize my investment.

[DrewQ45]

Drew,thanks for the post-it is one of the many I have read on the subject of condenser flushing,and the reason for my concerns .the fsm makes no mention of the type of condenser in the q,however there is NO talk of flushing either the evap or condenser mentioned in fsm when describing compressor replacement or any other service on the a/c system-makes me wonder if flushing is not the correct way to go.looking at the condenser gives no clue to its internal construction type as far as i can tell.It seems my quest for this information will help other board members when their time comes,as most seem as uninformed regarding this issue as I. Considering I what I spent for a brand new oem compressor,I want to be sure the process is effective and safe to maximize my investment.

There is no talk of flushing because the dealer probably expects you to simply replace components. You can gue$$ why.

I'm wondering why you are so determined to flush and what made you think your old compressor was no longer efficient even though it was still quiet. As you know, there are many reasons why it might not have been cooling right. Did you take any steps to determine that? Vacuuming, fresh charge of freon etc? I'm sure you must have before outlaying a wad but I must ask.

Do like Tech said and check for debris. Have the system evacuated and disconnect the lines to the compressor. Stick a long Q-tip or something white down into the tube and see if it comes back with black debris. You can also check the lines going into the drier etc. I say if all is well... just skip the flush.

[qship96]

Drew,yes the system has been evac/vac/recharged it was only down 4-5 oz since the initial fill in japan! the service still didnt drop the vent temps to where they should be,so a new compressor & dryer will be installed as they both have almost 189,000 miles on them.I have visually inspected condenser for clogged/bent fins,cleaned the leaves out between rad and condenser,and replaced fan clutch last year-condenser electric fan operates as it should,all diagnostics of electronic control per fsm check out ok.evap looked clean externally last year when I replaced blower motowhich leads me to believe the compressor is just no longer pumping as efficiently as new due to age-the only other part that could be contributing to this is a malfunctioning expansion valve which will be replaced if new compressor/dryer dont solve the problem.As far as flushing,I probobly will not flush since no-one seems to know about the 94-96 condenser build design and the fact that I do not want to tear into dash to remove evap to flush it{exp. valve cannot be flushed with solvent and must be removed before flushing evap} you are probobly correct in that the system most likely doesnt need flushing since the current compressor is being replaced BEFORE it gets noisy or seizes spewing its guts through the condenser

[maxnix]

I would suspect a clogged expansion valve, which a new compressor will not affect.

[qship96]

Brian,why would you expect that considering it still cools,just not as cold as it could be? I would expect the expansion valve to be the last to clog as any debris travels from compressor to condenser before ever getting to expansion valve.My understanding is that if exp. valve clogs,it stops ref. flow and you get no cooling as freon never makes it through the evaporator
Modified by qship96 at 4:56 PM 4/10/2007

[maxnix]

The smallest stuff will make it through the condensor, but not the expansion vavle.

In any case, I would look at it first and not assume it is clear of debris and deposits.

[qship96]

can you get to it without disassembling the dash?

[maxnix]

Maybe if you pulled the engine and cut through the firewall.

Check with an automotive AC professional specialist (does nothing else0 and see what he recommends.

[elwesso]

The evaporator isnt that hard to remove...!!! Maybe a 4-5 hour job tops... I took an evap out of a Q and it wasnt bad. Once you vacuum the system and then remove the couplings on the outside (on the firewall, theyre tough to get to but not torqued real hard), you take the entire black box out (the case that holds the evap).... It screws to the other pieces (the blower box and the box that then goes to the heater core) and then you pull the evap and its case out as one piece, and then seperate the case to get the evaporator out once its out of the vehicle...

The HVAC systme is very modular in that you can take a piece out without undoing everything. I would probably try and redo the foam seal/gaskets while in there, I know mine are wasted.

http://www.nicoclub.com/articles.php?id=196145

Its not hard at all.

Thanks for this thread. I am planning on taking all of my AC components out this spring and cleaning everything very nicely... I may not flush my condensor now due to this thread... Im not sure though, id think running SOMETHING through it would be better than nothing, because once you open the system the oil absorbs moisture, so thatd be the main reason id wanna get all that old oil out... I think my compressor works fine, however its like its working too good, the evaporator still ices over after about 15-20 mins of highway driving.... So hopefully that will fix it, and if it doesnt at least the system will be fresh for a new compressor.

My plan is to clean the expansion valve and evaporator, all flex lines, and reoil the compressor... Was planning on the condensor but im not sure now...

I do have a question. I have a seemingly good evaporator from my old Q, the AC worked so I assume its good.. When i took it out, I cleaned itout real good with a standard parts cleaner, and its been sitting in my attic ever since. Would I be better of cleaning the one thats in the car, or installing the cleaned one?

[DrewQ45]

\Im not sure though, id think running SOMETHING through it would be better than nothing, because once you open the system the oil absorbs moisture, so thatd be the main reason id wanna get all that old oil out...

I do have a question. I have a seemingly good evaporator from my old Q, the AC worked so I assume its good.. When i took it out, I cleaned itout real good with a standard parts cleaner, and its been sitting in my attic ever since. Would I be better of cleaning the one thats in the car, or installing the cleaned one?

Your system is probably icing over due to low freon. Try charging it with a can first.

AC system stays pretty clean unless the compressor grenaded. If you still want to clean the evap....

First get a vacuum.... $9 at harborfreight...

http://www.harborfreight.com/c...92475

Since you have an evap sitting and waiting... do all the work of getting to to the evap short of pulling the lines and prior to evacuating the system. One you're ready to pull the lines on the evap, evacuate the system, pull the lines then quickly connect the lines to your other evap. Immediately vacuum the system. Done in this manner, the oil won't have time to absorb moisture and neither will the receiver-dryer.

....Drew...

[elwesso]

Your system is probably icing over due to low freon. Try charging it with a can first.

AC system stays pretty clean unless the compressor grenaded. If you still want to clean the evap....

Fraid not, had it recharged last year, and it was not low when I had it vacuumed and recharged.... Same symptoms. Whatever it is its not due to low charge.

[qship96]

well,since no one here had a definitive answer on the later g50 condenser construction{tube & fin,parallel,dual parallel,surpentine,etc} I will stick with my original plan- new compressor and drier install-if that doesnt freeze my nuts off,I will then consider expansion valve and condenser replacement! Wes dont you have a old condenser laying around you can cut in half to check construction?

[DrewQ45]

You need to take it to an AC shop so they can eyeball the condenser if you can't tell by looking at it.

[qship96]

the work will de done at a shop,I just like to fully understand the procedure to ensure it is done the way it should be-

[Q45tech]

http://www.vertrelsolvents.com....htmlhttp://www.vertrelsolvents.com....htmlhttp://www.epa.gov/ozone/title....html

Unlike our trained gerbels for engine cleaning we are having trouble with fireants accepting the training protocols............nano-robots with be the answer.

Dealers want nothing to do with flushing and have only acepted transmission flushing because it was offered by independents.

I remember when an ex T3 employee brought the first BG Machine for a Infiniti dealer [he became service manager for a new ATL dealer launch] it caused waves and ripples from Atlanta to Japan..........engineers came fom Japan to inspect this device...........I was there trying to example the cost and PR benefits.

[qship96]

I think I have ruled out a bad expansion valve,as with todays moderate temps I was able to monitor evap get down to 43 degrees,then slightly warmup,showing it definitly opens{cools} and closes{ to not allow evap to drop below 42 so it does not freezeup} hopefully,this leaves the compressor/dryer as the culprits-they will arrive monday.