5th Generation Maxima (2000-2003) Learn more about the 5th Generation Maxima, including the VQ30DE-K and VQ35DE engines.

Recharging AC qs

Old 05-16-2019, 06:56 AM
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Recharging AC qs

If im recharging the AC but not replacing any components other than the drier/accumulator, do i need to add oil? Im finding nothing but conflicting info on this. My thought is no - straight r134a without additives is what i need, since vacuum purging wont remove oil? I dont want to add more and find out its too much and murder my ac compressor in the process. Plus less oil is safer than too much. Ill be using a manifold gauge set to do this, ive done it before on one of my 4th gens but i dont remember if oil was used or not.

If anyone could fill me in that would be awesome, starting to get too warm to go without AC any longer.
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Old 05-16-2019, 05:26 PM
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So it turns out there is a significant leak on the high pressure side. There is a distinctive hissing noise at the back passenger side of the engine bay, where it appears some hard lines meet the firewall. Of course it has to be the worst cvntiest spot ever. It appears that this is the evaporator coil, which means now i have to pull the dash to get to it... Im hoping this is bad as it gets? Does anyone have experience with this? My biggest concern is that the hardlines leading to the evap coil are damaged, idk how i will possibly replace them considering i dont know where to find replacements. I imagine it must of gotten bumped during the motor swap.

In any case - can anyone fill me in on how those hardlines connect to the evap coil? Maybe i could just use some sort of sealant when i reassemble? Thoughts?

edit: another question - how do i know which style of evap coil i need?
https://www.rockauto.com/en/catalog/...ator+core,6768
rockauto has 4 listed and they come in 3 different styles, how do i figure out which is correct?

Last edited by Slamrod; 05-16-2019 at 05:46 PM.
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Old 05-16-2019, 09:47 PM
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I just finished this job. I just wrote a big response and then my tab crashed. Here is the condensed version:

Do not add oil if compressor was factory filled and working fine before service. FSM AC section about filling compressor is a good read for general knowledge.

Lines at firewall connect to a TXV, I bought this one:

Amazon Amazon

TXV connects to evap coil, I bought this one-Four Seasons 54876:

https://www.rockauto.com/?carcode=1431954&parttype=6768

You may have tweaked something during your swap. I doubt your evap coil was harmed. I replaced mine because I replace everything.

Cabin airbox is a biatch but doable if you decide to replace your coil. I would say a 5/10. Took me about four hours both ways and I only broke a small piece of plastic on the white heater side pulling the airbox out but repaired it easy with glass and epoxy. There is no information on the forum other than one member I discussed this same issue with while he was searching for info. I can't find the thread to link, so here is a quote from the only other documented member to have done this with 5th gen and is what I used to guide me:

"For anyone that still needs info on this though it's not as common as the fourth gen, I didn't get a chance to take pics but I installed my new evaporator and expansion valve. Removed the glovebox (6 screws and the light connector). Unplugged and unscrewed blower motor, unplugged blower resistor, some sort of blend door connector towards the top, removed right front lower kick panel, removed the air bag assembly (2 twelve mm. Bolts and connector). This helps with getting to the upper evap housing bolts and upper crash bar bolts. Removed a ten mm to the right of the opening that holds a black connector relay housing. Removed 2 10 mm. Bolts for a small bracket to the right that the black plastic piece. Removed the 6-8 10mm bolts that hold the evap box to the dash, removed the two a/c lines on the engine compartment side of the firewall by removing the 10mm, pull the lines out, and then there is 2 allen head bolts, I can't remember the size exactly. Wiggle and pull out the expansion valve, then go inside and last but not least I removed the 2 12mm nuts that bolt the crash bar in. The airbag removal makes getting to the top but easier and I got the the lower 12mm with a semi deep socket, swivel, and a extension. Then either have someone pry out on the bar or like the other person said jam something under the plate. I pulled the weather stripping partially out of the door jam right next to where the roll bar is under the dash, used my knee and pushed on the pry bar while driving the box out and down, (please note while removing, release the white tab on top of the housing to the left where it meets the heater box cause you may break that). It's not easy to remove, deep breaths and making sure your not cracking or breaking anything. Then once you get it out it's 7 screws I think and 3 black spring clips that holds it together, remove the evaporator and replace. I used foam wrap around the lines that go through the firewall to help kinda seal against stuff coming in. I reinstalled everything, used new o rings on everything, you can spray them down with silicone spray or soak them in oil. I left the expansion valve for last since you can install it through the firewall side and I believe it helps with clearance. Hope this helps, sorry I didn't get pics, was in a rush. Takes about 2 hours"

If I were you, I would replace the TXV and associated O-rings, repair/reconnect the lines and pull a vacuum. It only makes sense that you hit the lines while lifting engines out/in. Probably just need to straighten them out and reconnect.






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Old 05-16-2019, 10:13 PM
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Originally Posted by User1 View Post
I just finished this job. I just wrote a big response and then my tab crashed. Here is the condensed version:

Do not add oil if compressor was factory filled and working fine before service. FSM AC section about filling compressor is a good read for general knowledge.

Lines at firewall connect to a TXV, I bought this one:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

TXV connects to evap coil, I bought this one-Four Seasons 54876:

https://www.rockauto.com/?carcode=1431954&parttype=6768

You may have tweaked something during your swap. I doubt your evap coil was harmed. I replaced mine because I replace everything.

Cabin airbox is a biatch but doable if you decide to replace your coil. I would say a 5/10. Took me about four hours both ways and I only broke a small piece of plastic on the white heater side pulling the airbox out but repaired it easy with glass and epoxy. There is no information on the forum other than one member I discussed this same issue with while he was searching for info. I can't find the thread to link, so here is a quote from the only other documented member to have done this with 5th gen and is what I used to guide me:

"For anyone that still needs info on this though it's not as common as the fourth gen, I didn't get a chance to take pics but I installed my new evaporator and expansion valve. Removed the glovebox (6 screws and the light connector). Unplugged and unscrewed blower motor, unplugged blower resistor, some sort of blend door connector towards the top, removed right front lower kick panel, removed the air bag assembly (2 twelve mm. Bolts and connector). This helps with getting to the upper evap housing bolts and upper crash bar bolts. Removed a ten mm to the right of the opening that holds a black connector relay housing. Removed 2 10 mm. Bolts for a small bracket to the right that the black plastic piece. Removed the 6-8 10mm bolts that hold the evap box to the dash, removed the two a/c lines on the engine compartment side of the firewall by removing the 10mm, pull the lines out, and then there is 2 allen head bolts, I can't remember the size exactly. Wiggle and pull out the expansion valve, then go inside and last but not least I removed the 2 12mm nuts that bolt the crash bar in. The airbag removal makes getting to the top but easier and I got the the lower 12mm with a semi deep socket, swivel, and a extension. Then either have someone pry out on the bar or like the other person said jam something under the plate. I pulled the weather stripping partially out of the door jam right next to where the roll bar is under the dash, used my knee and pushed on the pry bar while driving the box out and down, (please note while removing, release the white tab on top of the housing to the left where it meets the heater box cause you may break that). It's not easy to remove, deep breaths and making sure your not cracking or breaking anything. Then once you get it out it's 7 screws I think and 3 black spring clips that holds it together, remove the evaporator and replace. I used foam wrap around the lines that go through the firewall to help kinda seal against stuff coming in. I reinstalled everything, used new o rings on everything, you can spray them down with silicone spray or soak them in oil. I left the expansion valve for last since you can install it through the firewall side and I believe it helps with clearance. Hope this helps, sorry I didn't get pics, was in a rush. Takes about 2 hours"

If I were you, I would replace the TXV and associated O-rings, repair/reconnect the lines and pull a vacuum. It only makes sense that you hit the lines while lifting engines out/in. Probably just need to straighten them out and reconnect.






Bruh you are the man. Appreciate the help big time. Silly question but is the TVX accessable from the firewall/engine bay side? Or do you need to come in from the inside of the car? Write up makes it look like i could potentially avoid any of the behind-the-dash fckery, but i cant picture how the TVX could be removed from the evap coil through the firewall. Then again i didnt really get a good look because i didnt know what i was even looking for yet lol. If i gotta go through the dash i might as well just buy the evap coil and replace it while im in there so i never have to worry about it ever again, its only $40ish.

i think my first shot is going to be the ghetto route - disconnect the hard line and reconnect it with a tiny dab of rtv or something on the threads. Maybe ill get lucky and get away with it, function over form.
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Old 05-16-2019, 10:22 PM
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The TXV is easily accessible (and only, unless you remove the airbox under the dash) from engine bay side. Two screws fasten it to the evap coil. Only one bolt to remove the line set from the TXV. Like i said above in the "if I were you" line. That's all I would do because I think that's all you need to do

RTV on what threads? The suction line connection up top mid-way between the heads? That joint is O-ring sealed. No RTV needed.
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Old 05-16-2019, 10:30 PM
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Do you guys have the AC service machine? because when it's totally empty you need to vacuum the air out.
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Old 05-16-2019, 10:34 PM
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Originally Posted by krismax View Post
Do you guys have the AC service machine? because when it's totally empty you need to vacuum the air out.
Not necessary. He has gauges. All you need is a vacuum pump and gauges. But that's part of the charging procedure which he said he's already done before. This is a leak thread. Also, Slamrod, you're already completely dry, just pump up the system and pressure check it. Soap and water might save you a bunch of work.
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Old 05-17-2019, 07:27 AM
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Ahhh ok, now its making sense. I really didnt understand how it all connected together but the way you describe it mades it sound simple. Its a bit of a tight spot and it was getting dark so i couldnt really make out what was going on back there but now i think i got it. Im going to go ahead and order the TVX and oring set and see if that solves the problem, the AC worked before the swap so the evap coil should be just fine. Ill try disconnecting and reconnecting first though just to see if i can get lucky lol.

As for the system itself im using manifold gauges to hook up and monitor pressures. Also you can rent a vacuum pump from autozone for free, its a $160 deposit but the thing works, ive used it in the past as well.
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Old 05-17-2019, 07:16 PM
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Here is what you'll be dealing with. The only part inside the car being the coil.




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Old 05-21-2019, 04:53 PM
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So i replaced the TXV and appropiate orings. Leak is gone. However, im still having issues. Once the system is cleared, i go to fill the low pressure side with refrigerant. The high side goes up to around 60psi and the low side goes up to around 50ish psi if i let it, i tried going to 30psi and nothing happened so i went higher. Compressor does not engage at all. Does this mean my compressor is toast? Im not understanding what i am doing wrong, shouldnt the compressor kick on and pressurize the high side? Car is running and climate control turned low as it goes. It seems the low and high side are more or less equalizing with the remaining pressure of the freon can and nothing happens after that. Can feels like its still half full.

What am i missing here?
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Old 05-21-2019, 05:14 PM
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Get a temperature pressure chart for 134a. Im on mobile right now. Give me a few to get in front of a computer. You're not even close to the pressures you need to be at.
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Old 05-21-2019, 06:33 PM
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Originally Posted by User1 View Post
Get a temperature pressure chart for 134a. Im on mobile right now. Give me a few to get in front of a computer. You're not even close to the pressures you need to be at.
I feel like its a compressor issue. Normally, you fill into the low pressure port, and as you bring that side up to proper pressure, the compressor will kick on and push it to the high pressure side, effectively sucking the freon out of the can until its empty in the process. This is how it worked for me last time. Now, i go to fill the low pressure side, and the compressor never activates. This leaves me in the situation described above where the low and high side have 50-60 psi and are basically equalized with the can.

edit: i tried jumping the compressor as a last resort. Clutch engages but it has no effect on the pressure readings, which to me further suggest my compressor died somehow. I didnt really fool around with this a lot though, because i didnt want to create any new problems.
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Old 05-21-2019, 07:12 PM
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Check the under hood label. I think it reads 16 ounces or so IIRC. I didn't have time to check mine before I left. How are you measuring refrigerant? If you're using the 12oz cans, go ahead and dump one in with the car off. Start car, run AC full blast everything. Add second can 4oz (check total system volume) DO NOT slam liquid refrigerant into a running compressor! Charge with gas only, meaning do not invert the can. You are looking for a Delta T of around 45 degrees discharge air at 90F, more is better but again, too low and your coil will freeze. Not a common issue anyway as you'll hit your charge weight before that happens. Lot's of variables at play though. Lots of temp & pressure charts on google images. You want to check your discharge air temp with the windows down and the system on fresh air, not recirc, so we know exactly what's going on.

Also, good job on your leak fix! How did you test? Did you pull the system down for a while? You need to pull vacuum from both sides because you don't know if the TXV was open or closed. I don't know how it comes anyway. Whatever, pull vacuum from high and low service ports and leave for an hour or so. Maybe you did this. At any rate, if compressor was working fine before, no reason it shouldn't be fine now unless something happened during the swap. Let us know. Good thread as everyone is gearing up for summer and the Maxima AC is a pretty easy system to service.
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Old 05-21-2019, 09:16 PM
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Originally Posted by User1 View Post
Check the under hood label. I think it reads 16 ounces or so IIRC. I didn't have time to check mine before I left. How are you measuring refrigerant? If you're using the 12oz cans, go ahead and dump one in with the car off. Start car, run AC full blast everything. Add second can 4oz (check total system volume) DO NOT slam liquid refrigerant into a running compressor! Charge with gas only, meaning do not invert the can. You are looking for a Delta T of around 45 degrees discharge air at 90F, more is better but again, too low and your coil will freeze. Not a common issue anyway as you'll hit your charge weight before that happens. Lot's of variables at play though. Lots of temp & pressure charts on google images. You want to check your discharge air temp with the windows down and the system on fresh air, not recirc, so we know exactly what's going on.

Also, good job on your leak fix! How did you test? Did you pull the system down for a while? You need to pull vacuum from both sides because you don't know if the TXV was open or closed. I don't know how it comes anyway. Whatever, pull vacuum from high and low service ports and leave for an hour or so. Maybe you did this. At any rate, if compressor was working fine before, no reason it shouldn't be fine now unless something happened during the swap. Let us know. Good thread as everyone is gearing up for summer and the Maxima AC is a pretty easy system to service.
The problem is i cant even get one can into the system, even when the system is at negative pressure. It feels like half the can goes in and then thats it. Because the compressor is not activating, the pressure simply balances out between my AC system and the freon can and stays that way. Normally as you add freon, the compressor kicks on, packs it to the high side, and makes room for more freon on the low side. This is not happening, even when I jump the compressor, nothing is getting compressed. Wouldnt this suggest the compressor is toast if it wont compress anything, even when I force it to run? Idk why it wont work now when it did before the swap, but clearly that is the case now lol. Really at a loss on how to proceed. Is there something i am missing here? Im ready to say screw it and buy another compressor but I would be pretty ticked off if I did all that only for the problem to still exist.
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Old 05-21-2019, 09:29 PM
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If your pressures remain unaffected after manually engaging the compressor, then yeah, it is no longer a compressor lol.
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Old 05-21-2019, 11:16 PM
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Yeah, thats what i figured, i guess i just wanted to hear someone else spell it out for me just in case there was something else that i was missing and could account for the circumstances. Well that sucks. Considering the age of the car i guess i cant be that mad about it, but even so, im curious what killed it to begin with. It is worth mentioning that the AC i had before the swap was kinda sucky, like on a hot day it just barely made the car bearable to sit in. My 4th gens on the pther hand got ice cold, and that was with a black car and black interior soaking up heat as compared to my currently tan interior. For those of you with working AC, is it actually good? Was my AC on its way out all along, or does the 5.5gen AC just kinda suck in general?

So back to repairs - a new compressor is obvious. What about the evap coil? Brief bit of reading that i did says you should always replace the evap coil with the compressor in case of metal shards getting into it and clogging it up. I didnt see any such evidence of any material (other than neon green freon ofc) when i did the TXV. Opinions on leaving the evap coil alone? The stuff i read was just general, broad advice and not particular to maximas, so idk if it even applies. Wondering if anyone who has replaced their compressor and not the evap coil and had no issues, or did end up having issues.

I gotta say, sometimes i feel like some sort of Sisyphus, pushing a boulder up a hill only for it to roll back down over and over and over. Damn cars are like a never ending project lol.
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Old 05-21-2019, 11:29 PM
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Condenser is recommended to replace when a compressor craps out as it's next in line in the direction of flow. Evap coil is fine as compressor frag won't make it through the condenser coil, liquid line, then evap coil. It's too far. The green substance you are seeing is UV dye. As cheap as they are new, and as easy as they are to replace, I wouldn't even bother with diagnostics if I was remotely inclined to believe the compressor failed. Pull radiator, replace condenser, replace compressor, reinstall radiator, done.

For the sake of humor, I'm not sure what would be failing. A stuck reed would send high side way high, you're not even getting a pressure increase. Clutch may be engaging, but the compressor shaft may have failed. Why it engages manually and not with controls, not sure. I'd have to look at it. Try throwing a new pressure switch in. Or test yours. It lives on the driver side of the condenser. I replaced mine when I replaced everything. I still haven't used my system yet. I ruined the hose I had fabricated and have to go back to the hose guy this week, hopefully tomorrow. Getting too damn hot in Tampa already.
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Old Yesterday, 12:08 AM
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Yeah, im gonna wait til tomorrow to order new parts. Gonna mess around a little more just for curiousity sake, cant hurt since the thing is already toast. Im curious about that switch also, ill see what role that has to play in this saga.
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Old Yesterday, 12:12 AM
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Yep usually a switch for each side. Not sure where the low side switch is for this car, never looked. If you're bypassing all that though and pressures don't change then bad compressor obviously.
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Old Yesterday, 04:39 AM
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great thread !
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Old Yesterday, 06:00 PM
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Originally Posted by Prophecy99 View Post
great thread !
Yeah for me its not LOL. Just pulled the trigger on a new compressor, condensor, high/low hoses, and drier. Couple of hundred in the hole but it beats paying a shop 1200 to diagnose and fix it for me. AC should be like a damn refrigerator after this.

Ive been wanting to repaint the grill black but taking the whole bumper off just for that seems dumb lol. Now i finally have a good reason i guess.

edit: does anyone know if the OEM condensor is tube + fin, or parallel flow?
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Old Yesterday, 07:47 PM
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Why bother disassembling the front end? Pull the radiator. Accumulator/drier was a component of the condenser for mine, not a separate part -note: I opted for aftermarket on my evap and condenser coils, not even sure if what came with my car was oem so no idea about a separate drier, they usually come together-. Right to left parallel flow, no serpentine tubes.
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Old Today, 07:53 AM
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Originally Posted by User1 View Post
Why bother disassembling the front end? Pull the radiator. Accumulator/drier was a component of the condenser for mine, not a separate part -note: I opted for aftermarket on my evap and condenser coils, not even sure if what came with my car was oem so no idea about a separate drier, they usually come together-. Right to left parallel flow, no serpentine tubes.
I want to paint my grill black. Removing the grill requires pulling the whole front end off for some dumb reason. I figure doing that would also make getting at the condensor easier so i might as well do both of those jobs at the same time since im going to have to do it eventually.
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