cannot get pressure readings

[SULTAN]

Ok so i went in for a service call today to this residential house where a 2 ton keeprite system was installed. I hooked up the guage and i could not get pressure readings to go above 0 on both sides.
So i thought maybe my guage went dead on me, so i hopped on the van and got a new guage but i still had the same problem. So i am like wtf, maybe the system doesnt have any refrigerant, So i pressed down on the shreddar valve and out came the spring of refrigerant :) i started upt he system and its working perfectly. Any idea as to why i cannot get readings on the pressure guages to come up? Do some systems have some sorta valve that you have to open before hooking up the guages?

Thanks in advance

[The MG Pony]

Perhaps the depressor on your gauges are missing the pin on the valve core. I've had that happen in the past where the pin was slightly bent so it would slip off the depressor fitting on the gauges.

[cooldude]

could be the rubbers in your gauge line blocking up. ive had that before

[Abe]

Im pretty sure its the depresser on your gauges.
Some of those pins on the schraeder are low down and just beyond the reach of the depresser

What you can do is usinf the special tool unwind the scraeder a turn or two. Remember to lock it shut again once youve finished

[robin r33 gtr]

I had a unit once where my leads would not push the pin in far enough. So i had to get some long nose pliers and pull the brass bit out about 2mm on one of my leads.

[Andy W]

I am amazed you can not work it out, approach things methodically and the answer will be right in front of you.

[The MG Pony]

I am amazed you can not work it out, approach things methodically and the answer will be right in front of you.

Meh, we all have thoughs days where our brains just wont cooperate, hell, today took me 4 houres to remember how to use a reversing valve! When I was drawing out a blue print!

So give the guy a bit of slack! Mate :)