A/C Recharge Issues

[joeyofblades]

Hi all, new here. I joined to ask about recharging the air conditioning.

I watched tutorials on YouTube and bought the standard recharge kit. This is the second gauge/fill tool I've tried and gotten the same result. I hear the compressor on, the gauge reads near the bottom of the "green" area, I pull the trigger to fill the system, and the pressure comes back lower than it was before I tried to fill it. Then the compressor seems to shut off as if it's hitting the "overpressurized" failsafe that shuts it off. So, what, is the gauge wrong? My A/C blows cold but I wanted to top the system off and see if it could get colder.

Video: https://www.youtube.com/watch?v=FvCzAXRXgnc

 

[LeftieBiker]

Hoo, boy...

 

[joeyofblades]

Hoo, boy...

I don't understand your comment, am I missing something obvious?

 

[LeftieBiker]

Sorry - I was expecting other responses. I know that the SV and SL use an electric A/C unit, and that those use a different lubricating oil in the refrigerant. Using regular refrigerant will ruin the compressor in those. What I don't know with 100% certainty is whether or not the S uses the same unit. Sadly, I think that it does. Before you panic, though, let's wait for other responses from those who know more about it. Which model Leaf have you got?

 

[goldbrick]

Personally, I'd take it to a decent shop, have them remove everything in there and fill it correctly. I do 99% of my own car maintenance on multiple vehicles but I always use a pro for AC. They are licensed for a reason and I think those cans available at the auto parts stores should be outlawed. /rant off

 

[GerryAZ]

It is not likely that your system was low on refrigerant, but you may have escaped damage if the charging can was R-134A, did not have oil in it, and you did not keep trying to inject refrigerant for more than a few seconds. Since the compressor is hermetically sealed, variable speed, and operates at 360 to 400 volts DC, special lubricating oil must be used. Also, the control system manages compressor speed and system pressures so it is not obvious whether it is properly filled by just looking at low side pressure. I suggest you take the car to a shop that knows how to work on the LEAF's complex HVAC system to have it checked and corrections made, if necessary. A LEAF-certified Nissan dealer is probably your best option. You need to tell the technician what you did and why you thought you needed to add refrigerant. Also, take the fill kit with you to show the technician what you put into the system.

 

[goldbrick]

^What he said :mrgreen:

 

[joeyofblades]

It is not likely that your system was low on refrigerant, but you may have escaped damage if the charging can was R-134A, did not have oil in it, and you did not keep trying to inject refrigerant for more than a few seconds. Since the compressor is hermetically sealed, variable speed, and operates at 360 to 400 volts DC, special lubricating oil must be used. Also, the control system manages compressor speed and system pressures so it is not obvious whether it is properly filled by just looking at low side pressure. I suggest you take the car to a shop that knows how to work on the LEAF's complex HVAC system to have it checked and corrections made, if necessary. A LEAF-certified Nissan dealer is probably your best option. You need to tell the technician what you did and why you thought you needed to add refrigerant. Also, take the fill kit with you to show the technician what you put into the system.

Thanks for actually explaining it vs just saying "go to the dealership". I'll never go to a dealership for any kind of work and I'm not spending money on this Leaf I bought to be a daily driver piece of crap, but at least now I know I can't recharge my own a/c. I recharged it with this R-134A last year and been using the a/c for a year and nothing has gone wrong, but I won't do this anymore knowing what you've told me. If there's no way to recharge it on my own then I'll just stop using it once it runs out of refrigerant or try to recharge it with more R-134A.

 

[Nubo]

First thing would be to determine whether or not the system was operating within specifications. The service manual has charts where you can plot the ambient temperature vs. vent temperature under specific conditions (ac on max, windows open, etc.. (heat-pump and non-heat-pump units have separate charts). A vent thermometer is used for this task. If you're within specs, no need to go any further.

Systems with modern refrigerant are meant to be filled by weight, not pressure. There's no "sight glass" as with older systems. This involves vacuuming all the remaining refrigerant and recycling it, and filling the empty system with a specific weight of refrigerant using a scale.

As mentioned, this is a high voltage compressor which requires specific (uncommon) lubricating oil with high dielectric properties. Conventional AC compressor oil will ruin the system, as will use of leak-detecting dyes or stop-leak additives.

If the system has suddenly gone warm, that suggests a significant leak and it's pointless (and environmentally unsound) to refill without getting the leak addressed.

However (and this is my opinion only) I would consider "topping off" myself if the AC was under-performing after a number of years and had reached that point gradually (i.e., not a sudden leak that had dumped a lot of refrigerant). In such case I'd be sure to use just pure refrigerant (no oils, no dyes, no stop-leak). I'd begin by plotting the ambient vs vent results on the appropriate service-manual chart, and then add refrigerant in small increments, stopping to re-measure temperatures as I went. As long as the cooling performance was moving towards the specified range, I'd continue the cycle and I'd stop adding once well within that range. All this assumes the under-hood cooling fans are operating properly.