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Robinair 16256 Syringe-type oil injector -- Questions

FOMOCO on Tue December 30, 2014 7:08 PM User is offline

I just acquired a Robinair 16256 syringe-type of oil injector for R-134a. The instructions are rather minimal, and I have a couple questions on it.

It has a thumbwheel type LO side coupler, onto that is connected about 3 inches of hose, and then the syringe.

By using about 40 PSI of compressed air and a rubber-tipped blow gun, when coupled to an old accumulator I have, I played with it a bit.
It does not seem to have any sort of check valve in it, when coupled and coupler thumbwheel to OPEN, can blow air both ways through coupler and open barrel of syringe.

So... when in proper use, can the syringe piston pop-out due to LO-side pressure? The syringe barrel is 9/16" in diameter, so using Pie *RSquared, the surface area of the piston is .25 sq. in. which means, if coupled onto a LO side at say 40 PSI, there will be 10 pounds of pressure (40 PSI * .25 Sq. In.) trying to push that piston back out the end of the barrel. So, is this a two-person job? One to couple it on, while the other holds onto the syringe piston so it doesn't pop out?

And my other question is, how do I burp all air out of the hose after filling syringe with oil, before attaching to system? Do I put oil into the syringe, put the plunger in, then turn it vertical with coupler-end-up, open the coupler thumbwheel some, and push plunger slowly inwards until I see a little oil appear in the coupler?

The basic concept of this tool is simple, but I do not want to screw up due to lack of decent directions. Robinair's website was no help.

wptski on Wed December 31, 2014 9:05 AM User is offline

Not an answer but your using 40psi here but would it used with the system ON or OFF? If OFF the static pressure will be much higher and if ON, it would go up and down between cycles depending on the system. At 70F it would be around 70psi.

They have tools for changing a valve core while the system is pressurized and you are fighting the pressure part of the time.

FOMOCO on Wed December 31, 2014 11:29 AM User is offline

Here (hopefully) is a pic of the injector:

I just picked 40 PSI as a representative number, but when I was charging the system when it was warmer a week ago, I could keep it in continuous compressor run mode with all the doors and windows open w/fan on high. But if it did cycle, it would go up to 70 psi static. And lower than 40 when running.

I'm trying to finish up after a preventative replacement of the Receiver/Drier on the Escape (the possible without warning dessicant bag breaking open issue on the 2009 - 2012s). I want to add some more PAG 46 oil, as I found after I was done evacuating and charging it, there was a LOT of oil in my hoses! I think the placement of the charge ports in that cars system lend itself to pulling out oil. I think it's possible that I may have pulled out a significant part of the 2 oz. that I poured into the new receiver drier! I have never pulled out much oil on any other vehicle before!

So I'm OK on Refr. charge, but I am sure I am too low for my long-term peace of mind on oil. 'Course, now it's colder, and I have just been laid low by the flu!

Edited: Wed December 31, 2014 at 11:54 AM by FOMOCO

wptski on Wed December 31, 2014 6:57 PM User is offline

I have a similar cheaper one that but it has a 1/4" flare fitting but never used it. I ended up getting a Mastercool model with a 2oz or is it 4oz aluminum container that pulls it in under vacuum or push it in along with the charge. No instructions came with yours?

I have a 2009 Escape and while back the front end met a trailer hitch on a pickup truck!! They insisted on replacing the evaporator even though it was barely touched . They weren't going to replace the accumulator at that time but "now" I "think" Ford suggests any the system is opened to replace it. I should have paid the extra over the insurance to have them replace it.

FOMOCO on Sun February 08, 2015 12:20 AM User is offline

SUCCESS! - Well, I couldn't wait any longer to see if someone here had used one of these before. We are starting to use auto AC on the warmer days here, sun is getting more intense. I needed to get to it and get'er done.

I loaded the syringe with oil, put the plunger in, and holding it with the coupler-end down (not attached to the vehicle), tried to push in the plunger, expecting oil to come out of the open coupler. The plunger was hard as a rock, no oil came out, and if I pushed pretty hard, oil would very slowly start to bypass the plunger's O-ring. Not at all what I expected, I had expected oil to come out of the coupler, it didn't matter if the coupler wheel was open or closed, still no oil out of it.

While continuing to hold it vertical, I loosened the hose connection to the coupler, and immediately saw oil, so oil HAD gone down the blue hose to the coupler, just not OUT of the coupler. So I had real doubts then that this thing was going to work, as I did not see why oil couldn't come out of the coupler.

So... with coupler wheel CLOSED, attached it to the low side fitting, with engine at idle, AC ON, all doors and hatch were open, fan on High, compressor was engaged. While I held the syringe barrel and plunger end, then had my wife turn the coupler wheel to OPEN (depresses the Low-side port Schrader valve pin). The plunger immediately started to move down (in) under the pressure I was using to hold it. So then I slowly and smoothly pushed the plunger all the way down, inserting 1/2 Oz. of oil.

I then had her spin the coupler wheel to CLOSE, and then I removed the oil injector. SUCCESS! I reloaded it, and did it again, as I was looking to add 1 Oz. total.

So the manual oil injector works, and works well. I never felt any outward pressure on the plunger.

Considering all the testing I did before with it dry, I'm not sure exactly how it works. With oil in it and connected to the system, it acts as if there is an internal check-valve that prevents outward pressure from the AC system into the barrel, and a internal valve that will not allow oil to go out the coupler if the coupler is not actually attached to a port valve with pin depressed. Yet my previous testing with air every-which-way didn't show any of that.

Anyway, the Robinair 16256 manual Oil Injector works great, and it CAN be operated by just one person. Mission accomplished.

Edited: Sun February 08, 2015 at 12:26 AM by FOMOCO

wptski on Sun February 08, 2015 8:46 AM User is offline

Is there anything in the instructions about purging air from the injector? It appears that you'd be injecting a small amount of air into the system and air isn't good or the less the better.

FOMOCO on Tue February 10, 2015 4:47 PM User is offline

Here are the only instructions:

1. Remove plunger. Pour in oil.

2. "Jiggle" plunger to remove air.

3. Inject into pressurized A/C system.

That's it, the only instructions. The Robinair website did not have anything additional. P-poor instructions!

The fact that I had oil coming out of the hose-to-coupler fitting at least let me know that I had oil to the coupler. The largest volume after the syringe is the blue hose. With oil to (but not OUT OF) the coupler, that would leave whatever volume that is IN the coupler, that is not occupied by the port's Schrader fitting when it is engaged, and that looks like a very small amount indeed.

Still, I would have liked to have seen oil come OUT of the coupler when it was out in the open, before attachment to the service port.

Oh, the "jiggle plunger to remove air" instruction is for upon inserting the plunger into the barrel, to get rid of air on top of the oil... that goes quickly because the air compresses and slips right by the O-ring with any sideways movement of the end of the plunger. They just never tell ya what's next.

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