Attempting an A/C fix...little help please!

[Jay Willie]

Well, My '03 3.5 has been without A/C for a couple of seasons and, armed with what little I could find on the internet (and pouring over other threads in this forum; thanks to all the great posts!), I'm in the process of attempting to flush the system, replace the expansion valve, etc.

Only is any one aware of how to get to the evaporator where the expansion valve resides? Pics? Exploded diagram? Steps?

I've completed several diagnostic steps to determine that perhaps the filter at the expansion valve is restricted (don't know yet with what) and/or the valve is stuck closed. Ie; compressor turns freely (is not stuck or siezed), compound (low) side is balanced with high side while in static condition. With compressor engaged (engine running) and A/C full on (auto system set at 60, fan to hi) the low side goes into vacuum (about 12inHg) and high side sits around 57psi at 70degrees ambient.

I've got the dash tore down past the instrument panel on the driver side, a/c heater controls and vents removed, glove box out, and looking at a loose air bag. (Don't even want to think about attempting removal of this particular item...oh, and battery is disconnected and electrical system was discharged by leaving the headlight switch in the 'On' position.)

I'm thinking the unit looks like it might slide to the right and out the passenger side (behind and out the bottom of where the glove box used to be) once everything is unattached (a/c & heater hoses, wiring, etc.) and I've separated the heating and a/c units but I'm still scratching my head on this one.

Anyone ever tackled this before? Appreciate any and all advise of experienced veterans and pros.

Oh, and taking it to a qualified mechanic would presume a qualified mechanic (other than the owner...ehmm) occupys air space some'eres close to where I live. Haven't found one yet...(other than, well, like I said so I ain't sayin' much...)

Thanks again for giving this one a look see.

[RicerX]

Welcome to NICO! Sorry we didn't get to your thread sooner.

This being a very technical question (we get very many generalized modifications questions for Altimas but nothing like this), I'm going to zip over to some of the other forums where a few Nissan techs hang out and get them to look at this for you. Unfortunately, I'm not too experienced in the realm of Air-Conditioning systems!

Hang tight! Thanks for dropping by!

[Jay Willie]

Much thanks Xenon SE-R! I appreciate the attention. Feel free to also move this where ever, just be sure and let me know

Quick update:

Me being the self-made man that I am, I tore into this thing anyway...OMFGoodness! Contrary to popular belief, you don't have to remove the dash, instrument cluster, air bag, vents, etc., etc., etc. I now have experience with these particular items however, this doesn't necessarily preclude the idea I know what I'm doing.

I have completely removed all A/C components for a thorough flush and inspection with the exception of the compressor and the low and high pressure lines that are attached to the compressor. Upon general inspection I have been unable to determine what may have caused the vacuum reading on the compound (low) side of the system. I will replace the expansion valve anyway as most of the information I've come across suggests this may be my culprit, along with deteriorating hose particulate clogging other areas of the system.

There is a larger tube (approximately 1.625 x 9.1875 read in inches) secured to the left (driver) side of the condensor with two smaller tubes leading from the left condensor manifold to the bottom of this tube. In the tubing port closest to the condensor manifold there appears to be a cylindrical screen filter (.375 x 2.375) with a cotton filter media of sorts in the end .675 of the tube (farthest away from the port end.) Around the outer area of the screen filter there appear to be pieces of rubber in varying sizes, not very large and more slivery than chuncky (pieces of hose as per my research? Me thinks so.) The total accumulation of this debris is not adequate to completely close off the ability of R134A to pass through the screen; I would say an apporximate restriction of perhaps 15-20%?

I applied light (20-30lbs) air pressure to the evaporator, condonsor, and all hoses (with the exception of the hoses attached to the compressor. I'm a little uncertain about trying to push anything through the compressor; don't want to damage same) with no apparent expulsion of debris, etc. There appears to be unrestricted air movement overall but, since I'm unsure of the routing of refrigerant through the fins in either the condensor or the evaporator, I am not too certain that any portion of the condensor or the evaporator may possibly have some amount of blockage.

I have purchased a flush agent (Dura II A/C Flush Solvent) for cleaning out the system. I am also thinking with the particular type of debris visibly present in what I'll call the system filter, it also appears as if I'll need to replace a hose(s) but I'm thinking one or the other (high or low) isn't available to the GP?

Anyway, what a deal! I'll continue on and keep this thread current. Thanks again Xenon SE-R and all others scoping out my situation. Hope to draw some good attention.

Have a Good 'un!

For the professional technicians: am I doing OK so far?

[QR25DE]

Sounds like you are on the right track, but here's the question, when you ripped all this apart did any refrigerant leak? Was there any in the system? It may be going into the system but leaking somewhere. When you fill it do you fill it with the A/C on and running or off?

I'm sure you have covered this but just being sure.. lol

[Jay Willie]

Hey no problem with the questions, QR25DE. I know I've given just a little bit more information than usual , so I took this from my first post:

"I've completed several diagnostic steps to determine that perhaps the filter at the expansion valve is restricted (don't know yet with what) and/or the valve is stuck closed. Ie; compressor turns freely (is not stuck or siezed), compound (low) side is balanced with high side while in static condition. With compressor engaged (engine running) and A/C full on (auto system set at 60, fan to hi) the low side goes into vacuum (about 12inHg) and high side sits around 57psi at 70degrees ambient."

(In the above quote, I mentioned a 'filter' in the general vicinity of the expansion valve, not so. This filter appears to be in the dryer?, a tube located on the left side of the condensor. I talk about this more in my second post.)

So I'm thinking that you should be able to see I hadn't added any freon to the system since it appeared to be adequately charged. I do understand, however, that when freon is added, the A/C must be in operation (engine running, temp set to 60 degress for auto cool systems, fan to 'Hi') while adding a charge to the compound (low) side. I also know ambient air temprature is just one factor in determining a full charge in the system. This is all quite the freakin' science experiment, love it.... I did thoroughly inspect the system before scavaging the R134A and there were no apparent indicators of escaping freon.

I failed to mention this car just turned a hundred thousand miles and has operated flawlessly since new. (Still runs like a s/a ape and I haven't been more satisfied with any other second car. Love the styling, handling, performance, creature comforts, etc. Window operation seems a little less than the 'cool, calm, and collected' I would associate with the rest of the styling.) From what I've read elsewhere, this is right about the time the high pressure hose begins an internal 'sloughing' thus releasing what seem to be small flecks of material into the system.

More than happy to help with any other queries.

You all have a Good 'un!