A/C Schrader Valve


#1

I have a 1997 Chevy 1500 Sillverado 2wd with a 305 in it with an automatic transmission. The a/c is blowing warm and it took a charge but when we removed the gauges the refrigerent started to spew from the schrader valve. We tried to free up the valve while contaminating the shop and atmosphere but the valve remained stuck open. Is this valve serviceable or do i have to buy the whole a/c line and block assembly? At least we know where the leak is!

Thanks Chris


#2

They usually can be replaced like any other Schrader valve. I believe they are the same as those used in tires…


#3

I wish we still had stars, I would 4 star caddyman’s reply!!


#4

If it’s the one I’m thinking of it’s not a schrader valve but a service port. Has kind of rounded corners on the outside of the port? Anyway, that little port assembly is easily replaced–you just need to find the guy who knows the part. If it is just a schrader valve, don’t just grab one from a tire valve stem. They’re not designed for 250 psi or more…


#5

The low-side charging port never sees 250 psi…


#6

The R-134A ports are significantly bigger than the old R-12 Schrader valves. They may still be referred to as Schrader valves (I don’t know if they are or not), because they work the same, but I doubt a screw-in valve from a tire or an older A/C unit would work. I think you can still replace them the same, but you will need to get the right part. If you can find a tool to tighten your existing valve, it may just be loose or have a piece of debris jamming it. They are extremely simple and it’s hard to imagine how one would fail, especially on an A/C system, where they don’t get a ton of use.


#7

The valves are significantly different but theorizing here for a minute, I’m inclined to think the valve is not the problem and any leak is somewhere other than the valve.

Sometimes the 134 valves can bind or get canted sideways a bit. When the service hose is removed refrigerant will blast out of the binding or canted valve. Often a tap with a screwdriver, center punch, etc will straighten it out and the refrigerant flow will stop.
I’d be inclined to think the real leak is the compressor shaft seal.


#8

"The low-side charging port never sees 250 psi…"
No, but if I remember correctly the low side port is on the accumulator and the high side is on the hose assy.


#9

Here’s the tool required to replace the Schrader valve. http://www.fastenal.com/web/products/detail.ex?sku=0454314

Tester


#10

Schrader valves are so cheap, I wouldn’t bother trying to service one. Just replace it.


#11

You can buy a kit with two new schrader valves and the tool for your AC for a couple of bucks at any auto parts store. They are right there with the cans of refrigerant.