Automotive Air Conditioning Information Forum

I've got an 02 Xterra that I purchased in 2018 with the 3.3L supercharged v6. The back story; the aircon was inoperative when I bought it but it was winter here so it didn't bother me, and the truck had sat for 5 years prior. Come spring time I changed out the high side hose, as there was oil on it and it was obviously leaking at the crimp. Vacuumed it down, no apparent leaks, charged it up with the proper weight of r134a. A/C worked pretty well for a few months, but it was never super crazy hot at the time. Then the condenser failed, it looked physically damaged from a rock or something hitting it. Replaced that, and the drier again, vacuumed down and no leaks. Filled again with r134a as well as 2.5oz of oil as per the Nissan service manual. I did use the small cans but did bleed the air out of the hose after swapping each out. I used (2) 12oz cans as Nissan states 21.16oz - 24.69oz is correct charge level. Since some of it stays in the hoses I'm sure that put me in the middle of the range.

So the issue is the cooling at idle is beyond abysmal. Spraying water on the condenser made no change in the gauge readings. I was getting around 60psi on the low side and hardly over 150psi on the high, with a vent temp of ~60F . Outside temp was 85-90F with about 60% humidity. The spec from the service manual states 186 - 228psi on the high and 24 - 31psi on the low side at 1500rpm. It does reach this if you hold the motor at 1800rpm or so and it does get cold, down to almost 50F, the clutch fan is operating correctly. I want to condemn the compressor as it is 22 years old and is probably tired. I did this work in 2021 and I just got back into looking at it now that life has settled down. The good news is the system appears to still be full at least.

Funny enough my neighbour has the exact same vehicle, and let me test on his with my gauges. He gets 45F air at idle while mine is over 60F. And the readings look more inline with what you'd expect.

I noticed that sometimes, I'll hear a buzzing/humming sound under the dashboard, and there is next to no cooling, but of course could never replicate it with my gauges hooked up, until today. When it happened the low side stayed around 50psi while the high side skyrocketed to over 350psi. So now I am not sure what to think. Probably more than one issue. I never used any sealers or crap like that. Just pure r134a. When I talked to the previous owner, they never touched it, so they claim.

Parts for this truck are pretty cheap, thought about just replacing everything, but would love to figure out what the actual issue is.

Thanks in advance for any advice, I'm still pretty new to working on AC but do have a mechanic lined up to recover the existing r134a if I need to take it apart.

23 oz per All Data.

I can't tell if it was pumped down correctly or not in your post; it may be my comprehension of the thread. 50/350 means the compressor is working. My thoughts or areas I would address not knowing. Too much oil was added, it was overcharged, and there was poor removal of the heat load. I'd start confirming each in the shop and move forward once eliminated.

Tim wrote: ↑Fri Jun 21, 2024 7:24 pm 23 oz per All Data.

I can't tell if it was pumped down correctly or not in your post; it may be my comprehension of the thread. 50/350 means the compressor is working. My thoughts or areas I would address not knowing. Too much oil was added, it was overcharged, and there was poor removal of the heat load. I'd start confirming each in the shop and move forward once eliminated.

Thank you for the exact amount. Not sure why Nissan gives a range like that. I pulled a vaccum on it a few years ago now, I let it run for around 1 hour but I can't remember how many microns. I will try the water on the condenser test again this weekend and report back. If that does nothing I will get my mechanic to evacuate it and will do this all over again.

If it was too much oil, would it be easiest to just flush it all out and start with a new full oil charge?

Not tons different from Xterra, I have 1998 Frontier with 278K on factory compressor and 2004 Frontier with 118K that compressor seized and I replaced compressor, condenser, drier and backflushed high pressure line to fix. And their AC works very well, in Arizona.

I think I'd let that mechanic take a look at it.

I will ask him to check it out before doing anything else. I just find it odd that it would sometimes show normal pressures, then out of nowhere go way high on the high side, and then if you turn it off for a bit, it'll work normally again.

I also have a 2000 Frontier and it has never been touched, it'll freeze you out within minutes of turning it on. I did notice the Frontier has a condenser mounted fan whilst the Xterra does not. Neither does my Neighbours Xterra. Looks like they took them out for the 2002+ model years. I did replace the fan clutch on the xterra, it definitely moves tons of air... According to this post they were removed, what the heck. https://www.clubxterra.org/posts/495551/

If memory serves, your 2002 Xterra has a rotary-vane compressor installed as original equipment. Many of those compressors were trouble-prone from the beginning. Suggest replacing the 22-year-old OE unit with a piston compressor, which I believe a few manufacturers have been producing as drop-in replacements. Tim at ACKits.com, this Forum's sponsor, might be able to help you with that.

To maintain the compressor's warranty, you might have to replace the condenser (again), along with flushing the remaining components. Best practices state that the R/D is also replaced each time a system is opened.

JohnHere wrote: ↑Sat Jun 22, 2024 1:30 pm If memory serves, your 2002 Xterra has a rotary-vane compressor installed as original equipment. Many of those compressors were trouble-prone from the beginning. Suggest replacing the 22-year-old OE unit with a piston compressor, which I believe a few manufacturers have been producing as drop-in replacements. Tim at ACKits.com, this Forum's sponsor, might be able to help you with that.

To maintain the compressor's warranty, you might have to replace the condenser (again), along with flushing the remaining components. Best practices state that the R/D is also replaced each time a system is opened.

Had to add it. My website is so jacked up these days. Even the non-piston has no applications set to the item. Something happened, and too much to catch with thousands of parts.

Clink Link for 14-4008P

celeron wrote: ↑Sat Jun 22, 2024 7:27 am I also have a 2000 Frontier and it has never been touched, it'll freeze you out within minutes of turning it on. I did notice the Frontier has a condenser mounted fan whilst the Xterra does not.

My 1998 and 2004 4-cylinder Frontiers have engine-driven fan clutch and fan only, no special condenser fan.

Update: I fixed some of the compressor links for this on our parts site.

Cusser wrote: ↑Sun Jun 23, 2024 7:45 am

celeron wrote: ↑Sat Jun 22, 2024 7:27 am I also have a 2000 Frontier and it has never been touched, it'll freeze you out within minutes of turning it on. I did notice the Frontier has a condenser mounted fan whilst the Xterra does not.

My 1998 and 2004 4-cylinder Frontiers have engine-driven fan clutch and fan only, no special condenser fan.

Ahh, mine is a V6, my wife drives it mostly, so if the AC had an issue I'd hear about it.

Tim wrote: ↑Sun Jun 23, 2024 8:34 am Update: I fixed some of the compressor links for this on our parts site.

Thanks, do you offer shipping to Canada? Always a massive cost getting parts here. NAPA wants almost 900 for a new compressor when I called them. Insane. If not I can ship to a place in NY that we cross border shoppers use.

JohnHere wrote: ↑Sat Jun 22, 2024 1:30 pm If memory serves, your 2002 Xterra has a rotary-vane compressor installed as original equipment. Many of those compressors were trouble-prone from the beginning. Suggest replacing the 22-year-old OE unit with a piston compressor, which I believe a few manufacturers have been producing as drop-in replacements. Tim at ACKits.com, this Forum's sponsor, might be able to help you with that.

To maintain the compressor's warranty, you might have to replace the condenser (again), along with flushing the remaining components. Best practices state that the R/D is also replaced each time a system is opened.

I read that on another forum I'm on as well where someone was replacing their compressor, a card came in the box stating this. They are cheap enough (as is the condenser and r/d) that it wouldn't bother me too much.

Ended up taking it over yesterday afternoon and we recovered the r134a, got 18oz out of it so it was actually a bit low. Recharged with 23oz after pulling a vacuum for 45 minutes, and let it run for a while. My fan clutch is not engaging soon enough after the ac is turned on, so it that explains my crazy high side readings. Held it at 1500rpm and let it run for 15 minutes. It began to cycle and the pressures were like this: https://i.imgur.com/vIaRBPm.jpeg The temp outside was around 22C and around 70% humidity. I measured the vent temp at 36F (sorry for mixing F and C, I'm in Canada but the vent thermometer only read in F). Seems to cool and dehumidify well but will need a warm day to test it. I still have my doubts about how it will handle in traffic on a 40C humid day. If it's still bad I think I will do what JohnHere suggests and replace the compressor with the updated version that is a piston style.