Automotive Air Conditioning Information Forum (Archives)

westcl2 on Wed May 14, 2014 11:44 AM

Year: 2007
Make: Nissan
Model: Sentra
Engine Size: 2.0L
Refrigerant Type: R-134a
Ambient Temp: 80
Pressure Low: 80
Pressure High: 50
Country of Origin: United States

So in my previous thread it seems that replacing my compressor is necessary. I've already purchased a replacement compressor but this brings me to the next questions.

What all do I need beyond basic tools?

I know I need to create a vacuum to make sure the system is leaking too bad and to ensure no contaminants enter the system when refilling. I don't really want to purchase a vacuum pump for a single use and just leave it on my shelf collecting dust. Is there a way I could use an air compressor to create the vacuum necessary? Figure at least w/ a compressor i could run a nail gun or something later

Are there any other components that I should probably just bite the bullet and replace while I have access to the area sans compressor?

wptski on Wed May 14, 2014 12:56 PM

Harbor Freight sells air compressor operated vacuum pump like dirt cheap but I don't know how good it works in real life.

Jag987 on Wed May 14, 2014 2:38 PM

They don't work very well. They take forever to draw a vacuum and then it is not a very "deep" one. It would be better and likely cheaper to replace the compressor along with the dryer and expansion valve then take it to a shop and let them pull a good vacuum and recharge it with the proper equipment. Depending on why the compressor is being replaced, the condenser should also be replaced and the rest of the system flushed. I hope you get back to cooling soon!

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I bought a can of 134a at w**-mart that had a stop leak, oil, and dye in it. It also had a hose and a gauge, so now I'm an AC pro!

westcl2 on Wed May 14, 2014 3:50 PM

I'd like to avoid buying as much as possible, is there a simple way to see if those components need to be replaced?

mk378 on Wed May 14, 2014 4:14 PM

From your other thread (don't do that) you have a compressor that spins but doesn't pump, it has very likely shed bits of metal which will (for the most part) get stuck in the condenser.

westcl2 on Wed May 14, 2014 4:34 PM

Couldn't I just flush the condenser out?

Jag987 on Wed May 14, 2014 9:01 PM

If there is metal in it, you can flush it. Then replace it and your new compressor a few days to weeks latter. Do it right the first time. We are all hear to learn and help. Spend the money once and do it right the first time. If there is no metal in the condenser, then flushing it to remove the oil would be fine. That way, it is known that there is no oil in the system and the correct amount can be added back.

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I bought a can of 134a at w**-mart that had a stop leak, oil, and dye in it. It also had a hose and a gauge, so now I'm an AC pro!

westcl2 on Thu May 15, 2014 6:02 AM

Valid points. Ok so condenser, anything else I should be replacing?

westcl2 on Thu May 15, 2014 7:42 AM

so did a bit of the googling, and will be replacing compressor, condenser, drier, and the expansion valve. And then either going to a shop and having them pull a vacuum on it or I'll just get a pump depending on which one will cost less.

I have a general idea of how to do these replacements, but are there any youtube videos anyone trusts/recommends to streamline the process?

Thank you all for the help

Jag987 on Fri May 16, 2014 12:21 AM

Good call on doing it right the first time. Here is a Link to a post about how to do the recharge.

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I bought a can of 134a at w**-mart that had a stop leak, oil, and dye in it. It also had a hose and a gauge, so now I'm an AC pro!

westcl2 on Fri May 16, 2014 3:37 PM

@Jag thanks for all the help. Will probably be doing this in a week or so after all the parts have arrived and over the long weekend.......fingers crossed

westcl2 on Tue May 20, 2014 10:23 AM

how do i know how much refrigerant oil my system needs? i looked at the fsm for my car and it gave me a list something liek this for everything but the compressor

condenser 75
evaporator 75
major leak 30
etc
then on the compressor it says that it has a max capacity of 150

do I just take all the components I'm replacing and add them up?

I'm replacing the compressor, condenser, and expansion valve

Edited: Tue May 20, 2014 at 10:52 AM by westcl2

westcl2 on Tue May 20, 2014 10:52 AM

think i figured it out on my own, but new question. it appears like the entire system should contain 150 mL of oil.

Since i'm not replacing the evaporator does it reduce the amount i need to add? If i were to replace only the evaporator it says i should add 75 mL, does it store that much inside? meaning i should add a total of 75 mL?

What's the best way to add this oil into the system? i've seen videos of people pouring it into the center yellow hose on the manifold guage and into the cavity of an opened up compressor.

mk378 on Wed May 21, 2014 8:33 AM

There's no way to know how much oil is in the evaporator now. Best practice is to flush it out then you know there is no oil there, so then you would use the full system amount of new oil. Oil is typically put into the compressor inlet before installing. Using oil with UV dye (which you can buy pre-mixed) will make finding any future leaks easier.

westcl2 on Wed May 21, 2014 1:37 PM

seems reasonable. So since this entire thing is going to be disassembled is there anything else I should consider doing before I put it back together?