Manifold Gauge Hoses

[TheJackal]

OK, so I'm gonna sound like a total n00b on this one, but I bought a set of manifold gauges at Advance a little more than a week ago since I noticed my A/C system's performance left something to be desired. Turned out I needed refrigerant. So I decide to add the refrigerant and attach the tap valve and can to the end of the yellow hose. I opened the tap valve and opened the blue service valve. I come to the realization that the system is not taking any refrigerant in. The low side pressure was 35 at the time.

So I'm pretty much baffled at this problem, when I remember the yellow hose has a type of valve inside of it that only opens the hose when something's connected (ie, doesn't allow refrigerant to escape and air to get in the manifold). The problem is it appears to be holding back too much pressure.

I ended up using a little bit of redneck ingenuity to add refrigerant to the system. I disconnected the blue low pressure hose from the service port and then from the gauge set, attached the tap valve to the gauge end, purged the air from the hose, attached it to the low side port, and then began charging. Of course, the problem now was I could only monitor the high side. To check the low side pressure I had to reverse the above procedure. I was already tired of that the first time I did it...

Also these hoses don't have valves on the ends of them. I thought EPA regulations required that, but on the box it said that the auto-close feature of the quick-disconnect ports were enough to satisfy EPA requiements.

Anyway, what do you think the issue is? I can't seem to figure out what I'm doing wrong.

 

[manaen]

Did you have the AC running on MAX when you tried to fill it?

and was the AC compressor running ?

what was the ambient temp when you were running these tests?

BTW.. no reason to feel like a noob, jumping in and doing this stuff is the only way to learn.

 

[TheJackal]

Yep, Max A/C with fan on highest setting. Doors closed with windows down.
Temps have been 90°F, with humidity being anywhere around 60-70% this week. (had to do this over 2 days, it was getting ready to rain one day and was forced inside) Compressor was running the whole time.

 

[MountaineerGreen]

Depending on the gauge set, there may be a valve in the manifold to let freon into the low side. My gauge set it took me forever to figure out, the gauge itself is the valve knob. Turn the gauge, open the valve.

 

[TheJackal]

That sounds like the Quest set:

I saw it at AutoZone for $33, I almost bought it for the hoses but then realized that it was on the wrong peg and the actual price was $70. I guess I should've asked if they'd give it to me at that price, but I didn't feel like waiting in line.

and yes, the valve was open, but nothing was going in. Here's what mine looks like, it's the Interdynamics MG-134HD from Advance:

The gauge set itself is fine, it's just the yellow hose I have a beef with.

 

[MountaineerGreen]

Ahh- I got my gages for $30 something dollars last summer. But that is the set.

 

[TheJackal]

Had to return something to AutoZone today, and since the Quest gauges were still there and marked as $37, I decided to pick them up. They actually did honor the $37 price, too. So next time I need to add refrigerant I'll swap the hoses and see what happens.

I'm guessing the Schrader-type valve in the end of the ID hose would work better if I was using the large jugs of refrigerant, but since I can't get those (nor would people around here appreciate me having all that crap around here ) I need something that's going to work with the little tap valves.

 

[KPT]

You may have had the hose reversed. Usually only one side has the piece that depresses the valve core:

The end on the left side has it in that pic.

 

[TheJackal]

I had the end with the valve in it connected to the can tap. The other end was connected to the manifold. I was pretty sure it went that way; I did try it the other way too just to make sure but nothing would come out then.

I did think about removing the valve but I don't have any tools that size. Now that I've got another hose to try, I'm not going to worry about it.