Any A/C servicing experts here?
 

This is not for my vette, but another car I'm working on.

I accidentally discharged the A/C and lost an unknown (but non-trivial) quantity of oil. System working perfectly before this. :banghead:

From reading online, it looks like the right way to fix this is to drain the oil out of the compressor and valves, and flush the lines, evaporators, and condenser in order to get the oil out of them, so that I can put in the factory-specified amount of oil.

My air compressors are 300 miles away so I'm going to have to pick up a cheap compressor to do the flushing with.

Anybody know what kind of psi you should flush at and what kind of cfm is needed at that psi?


My plan is:
- remove compressor, condenser, valves and drain the oil from them
- run a flush through the pipes going to/from the main evaporator
- run a flush through the pipes going to/from the rear evaporator
- run a flush through the condenser
- reassemble with new dryer and seals
- evacuate & leak test
- recharge

2008 Sienna / R134 / dual-AC system in case that matters.

I already have a decent manifold set. Will buy or rent a vacuum pump.

Leaning towards FJC 2710 flush kit or similar and FJC or four seasons flush chemicals.

My A/C experience is limited to topping up and basic diagnosis, so if you have any suggestions I'm all ears.

If it is vented and air can enter, like say you removed a hose, I'd change the receiver/dryer and have a shop do the fill for me.

Because you lost refrigerant doesn't mean you need to flush system. If the compressor fails, you would want to flush or add filter to catch debris. What did you do to discharge the 134a? Did you reconnect___after you caused discharge?

..... No need to flush for an accidental discharge ... you just need to add some oil ... check oil type and quantity @ your local auto parts store ... while there , check on refrigerant quantity also ... Lets say your system holds 8ounces total ... add about 75% , or 6ounces of oil downstream of the compressor before charging the R134 ... while charging , place a large fan in front of the vehicle to direct air through the condenser ... this step is most important .....

I lost a fair amount of oil, and am concerned about not knowing how much oil to add.


What I did was loosen the screw holding a sensor on the side of the compressor.

Was trying to disconnect the wiring harness and couldn't find the disconnect for that wire and in a moment of dumbassery thought "I'll just unscrew this."

Right around the time a voice in the back of my head said "Hey, that's probably a sensor and probably has pressure behind it!" is when it went 'hiss' and I couldn't reconnect due to pressure...

As soon as it was done and the cloud cleared from the garage I re-sealed it.


The reading I've done online indicates that the only way to get back to the right amount of oil from here is to get the existing oil out of the system, thus the flush.

If you have expertise that says otherwise, I'm all ears.

So it's a reasonable rule of thumb to assume 75% oil loss in this situation?

I'd be thrilled to not have to go through the flush...

So just pour out the oil and start fresh. Have a shop recharge it.

Your are going to want to re-start the whole process, find out the "Correct" quantity/volume and type of oil and then go shopping. Since there are too many Unknowns in your situation just get the materials and do it properly from the start.

Harbor Freight sells a nice Two Stage vacuum pump designed for A/C work for less than $100 on sale.
I have one and I love cleaning out the system and pulling a good vacuum and being sure it actually holds. Then add oil and recharge it yourself if you already have the gauges. The toughest part is the scale for weighing the Freon. I use the gauges and calculate or snitch my wife's kitchen scale.

AKLIM, I have the same Auto XRAY Scanner you bought. It works well for some cars and others don't recognize it. For my German cars I use ROSS-TECH software and my new scanner for my United States built cars is a "Launch-Creader-VII - 7 plus" and it works just fine.

I have to say I do miss a original OBD Software made to run on Windows/DOS" PC's. That software is lost to me but saved my butt multiple times. I had a flaky O2 sensor on a brand new car and they did not believe me. After seeing the data from before, during and after the incident the tech replaced the sensor. Then they wanted to know where I had bought it as it had more info than the GM standard software.

I still believe the best darn diagnostic tool is the POWER PROBE 4. It is one of the most used tools in my garage. I recommend this tool to so many people as I have found it to be so useful.
https://www.powerprobe.com/pp401as-page/

Having a Fluke 88 auto meter is nice but the power probe does so much more. I use the Power Probe more often than the Fluke in a lot of projects.

I wish the OP the very best luck in getting that AC working properly soon. It is starting to warm up here in Virginia isn't it? You are going to need it soon.
Regards
Chris

The accumulator can hold some excess oil. There oil in every component so if you plan to take the truck apart knock yourself out. Add 3 oz pag oil and evacuate and charge it. If you don't have a vacuum pump you will have to have someone charge it for you. Tell them what happened so they add a little extra oil. You're not the first and won't be the last to have this happen.

Taking it apart isn't really a big concern - I'm about 99% done with dropping the drivetrain out, radiator is out, bumper is off, propshaft is out, etc.

True but it is really hard to find a shop with a scanner so I have to have one for that. For my MBs, my tech has a copy of WIS and for the diesel truck, it doesn't work.

I am trying out ALDL Scan. Also have a MT2500 now I have the Auto Xray that works also. My old one broke.

Does it manage to do multiple sensors at the same time?

GM uses PAG oil in their 134a systems.

Thanks all for the guidance.

The assumption that all the oil came from the compressor makes sense, especially since the system had been at rest for a few days.

Haven't been able to find a spec on oil for just the compressor - FSM only gives a number for the condenser. Still hunting!

Will let you know how it turns out. Have a few days of other repairs in front of me before I can get to the A/C.