Car holds vacuum just fine but does not take refrigerant

[Summerstoohot]

I tried searching on this topic but I keep getting an error, so I created a post to ask.

I installed a new compressor without turning it and it doesn't seem to be engaging.
I will be turning it to loosen any seals and then trying to recharge again.

I was told at a shop that the car should take refrigerant regardless of the compressor engaging.

A few years back I was able to recharge with a gauged can of r134. Then the next time I tried it, the pressure
went into the red on the gauge. I left the ac alone for a few years then decided to try changing the compressor
as it seemed to have stopped kicking on for good.

I did talk to a mechanic at the shop, and it seemed he wanted to completely replace the entire ac system
for up to $2,500 rather than isolate the problem, which I wasn't in the mood to do for a 2006 Mercury Mariner with a lot of miles

Any suggestions on how to proceed ?

[JohnHere]

A few points of discussion to start:
--Did you replace the Accumulator?
--Car holds vacuum, but did you evacuate the system for at least one hour before you attempted to charge it?
--Did you use pure R-134a without any additives or sealer in it?
--Did the new compressor come with any oil in it?
--The compressor won't engage without any refrigerant in the system, but a system under vacuum should pull-in at least some refrigerant.
--Did you remove the Orifice Tube to see whether it had any gunk clogging it?

[Summerstoohot]

A few points of discussion to start:
--Did you replace the Accumulator?
--Car holds vacuum, but did you evacuate the system for at least one hour before you attempted to charge it?
--Did you use pure R-134a without any additives or sealer in it?
--Did the new compressor come with any oil in it?
--The compressor won't engage without any refrigerant in the system, but a system under vacuum should pull-in at least some refrigerant.
--Did you remove the Orifice Tube to see whether it had any gunk clogging it?

Hello sir , thanks for the detailed reply.

Did not change the accumulator.
I did evacuate for about 45 min to 1 hr.
used pure R-134a
I dumped the shipping oil from the compressor and replaced it with fresh
I made sure to turn the new compressor with the spanner
I did not check the Orifice Tube, I had not heard about this in anything I studied but I will find that and check it.

I tried charging it again today, and I can hear the refrigerant when the tap hit the can opening, then it stopped as I opened the tap fully.
I went to bleed the charging hose but heard very little to nothing and no refrigerant at all spritzed out.

I am wondering if the tap is bad now, or perhaps the anti-blowback charging hose has a problem. I will start with getting a new tap
from Harbor Freight and see if it flows at all.

[JohnHere]

I would check the OT before doing anything else. Recover the refrigerant, pull the OT, and see what it looks like. Clean is good. If it's clogged with black gunk, as well as metallic and plastic particles, that's not good. If it's the latter, then you have a lot more work to do and additional parts to replace. In any case, the accumulator has to be replaced every time you open the system.

As for charging the system (presuming you're using the newer self-sealing 12-ounce cans), you would turn the valve on the can tap fully clockwise, which is counter-intuitive, to release the contents of the can into the system. If that's not the problem, then there's something else wrong with your charging set-up.

[Cusser]

I tried charging it again today, and I can hear the refrigerant when the tap hit the can opening, then it stopped as I opened the tap fully.

This sounds to me like you have the newer style "self sealing" R134a cans, mandated by USA government. So if you have an R134 can tap that was purchased before such cans were mandated, the pointy probe of that can tap only works if you screw the valve completely down, then unscrew the valve just a little bit; if you unscrew too much, then the actuator will not push down the seal in the can and no refrigerant will come out.

You'd need either:
...an inexpensive plastic can adapter
...a new can tap which has a blunted actuator especially for such cans
...or a can side tap apparatus

[JohnHere]

The specifications that I have for your '06 Mercury Mariner are as follows: 32 ounces net weight of R-134a, and 7.0 fluid ounces of PAG-46. If you have an under-hood decal with specs that differ, the decal takes precedence. It's very important to get these amounts exactly correct.

Charging it like you did previously by using a can and color-coded gauge "kit," it's very likely that you don't have the correct amount of refrigerant in the system anyway. What's worse, you might also have inadvertently injected sealer into the system. If you still have that kit, check the can to see whether it contains any sealer, and let us know.

[tbirdtbird]

Ok I think he mentioned that he used pure 134, but looking at the used cans closely for the ingredients is not a bad idea.
Several thought come to mind.
1. Were both handwheels and both thumb wheels open when he vacuumed? Ie you pull the vac from BOTH sides of the system. We have had a lot of trouble with that on this forum this summer.
2. Did he close the high side hand wheel when he charged?
3. Many of us find the new 134 cans to be very cumbersome. Cusser, you mentioned the side tapper tool, that really is the way to go.

So was the vac pump actually pulling from both sides of the entire system? Ie was he installing 134 into the system, or just into the manifold gauge set (MGS).
Were the hoses bled to get the air out of them?
If he saw a good vacuum in a very short period of time, then he has only vacuumed the MGS, and not thenAC system of the car.

The OP gave a very deliberate response to the last set of questions, maybe he will do that again.