2005 Accumulator Schrader Valve question

[Blk00ss]

I have found our AC leak. Its definitely coming from the connection where the electrical pressure switch connects to the accumulator. We already replaced the pressure switch, but it has a slow leak. I have 2 questions

1) Is there a Schrader valve behind where that electrical sensor plugs in? I assume so? Does anyone have PN?

2) I assume this is under pressure and when I thread the sensor off, I assume it'll leak/ spray? Maybe not if the Schrader valve wasn't leaking?

 

[Blk00ss]

Just realized this is in the wrong section. Our Tahoe is an '05

 

[Fless]

Moved it here for you.

 

[nonickatall]

Normally there is no valve behind the pressure switch in the accumulators.

The system is under pressure, if you unscrew the pressure switch, you lose the refrigerant.

So you have to evacuate the system, replace the pressure switch and then refill it. I usually seal the thread of the pressure switch with teflon tape from the plumbing trade, if if the pressure switch does not have a sealing surface with an O-ring

That seals reliably.

 

[OR VietVet]

More Information for GM GENUINE 1550156

Sorry, unless I misread the OP's statement, there is a shrader valve at the threaded male port of the accumulator, where the pressure switch threads on. If you look at the link description, it says-"includes seal". The seal is an o-ring inside the threaded female portion of the switch and there is a little nipple inside there too that pushes the spring loaded plunger on the shrader valve, that is threaded in to the accumulator male threaded stem.

 

[nonickatall]

I have never seen an ac accumulator with a Shrader valve beyond the switch. Shrader valves are normally the valves for filling the system. I wonder why a car manufacturer should ad a Shrader valve beyond the pressure switch, when you normaly more often evacuate the system in a regulary air conditioning service, then when exchange the pressure switch.

Additionally, when the switch is brocken, mostly it leaks. And when it leaks, you have to evacuate the system anyway, even if you could replace the switch without further loss of refrigerant.

But you never stop learning...

 

[OR VietVet]

I have removed and replaced switches at the accumulator without evacuating the system. Unless the design has changed.

 

[nonickatall]

I have removed and replaced switches at the accumulator without evacuating the system. Unless the design has changed.

Ok... interesting...

Propably at OEM but at normal Rockauto stuff? They build in a valve, nobody needs? Except when you change the pressure switch, which should, from the view of such manufacturer, immediately lead into a Akkumulator swap?

I will give them a call and tell them, where they can safe money, without negative impact at the customer...

I'll get a well-paid consulting contract with the Chinese...

 

[OR VietVet]

It was designed that way, on purpose, so that the switch, which has a higher failure rate than the switch at the compressor, could be changed easily without dumping the whole system.

 

[nonickatall]

It was designed that way, on purpose, so that the switch, which has a higher failure rate than the switch at the compressor, could be changed easily without dumping the whole system.

Come on. They reduce quality in the switch to save money and invest that money in a useless Shrader valve, what you would not need when the switch would be reliable?

Sound to me like German Politic...

 

[03catburban]

That's how it's designed you can change the pressure switch without having to recover the refrigerant

Being a technician, them being designed like that has saved me alot of time on the job

 

[nonickatall]

That's how it's designed you can change the pressure switch without having to recover the refrigerant

Being a technician, them being designed like that has saved me alot of time on the job

How often does this pressure switch fail? I'll order 20 pieces right away...

No seriously, in all my years as a car technician I've definitely had 2 faulty pressure switches, but 20 faulty air conditioning condensers, 5 faulty compressors, faulty lines, leaks, electronic problems and so on.

And if your pressure switch is leaking, you don't know what amount of cooling refrigerant is left in the system, so when you do it in the right way, you have to evacuate the system, measure the amount of cooling refrigerant, set the system to vacuum, to remove humidity and refill the system again, what an automated air conditioning service system, what I have in my garage, all do automatically.

So I really wonder, why the manufacturer build in this valve, which has absolutely no sense.

But if they have it.. Great ...

 

[OR VietVet]

Come on. They reduce quality in the switch to save money and invest that money in a useless Shrader valve, what you would not need when the switch would be reliable?

Sound to me like German Politic...

I have never ever seen, on GM vehicles at least, an accumulator that did not have a shrader valve at that port.

 

[OR VietVet]

How often does this pressure switch fail? I'll order 20 pieces right away...

No seriously, in all my years as a car technician I've definitely had 2 faulty pressure switches, but 20 faulty air conditioning condensers, 5 faulty compressors, faulty lines, leaks, electronic problems and so on.

And if your pressure switch is leaking, you don't know what amount of cooling refrigerant is left in the system, so when you do it in the right way, you have to evacuate the system, measure the amount of cooling refrigerant, set the system to vacuum, to remove humidity and refill the system again, what an automated air conditioning service system, what I have in my garage, all do automatically.

So I really wonder, why the manufacturer build in this valve, which has absolutely no sense.

But if they have it.. Great ...

With ANY a/c leak, you have no idea how bad the leak is till you recover the refrigerant and weigh what is removed. I can't help it if the switch/port design makes no sense. It was never a different design, since I started in and was in the shops. You have never seen me suggest here that anyone just add refrigerant and can have complete confidence that the system was exactly correct as to whether it was full or over full. I always recommend complete recovery and refill as per specs. Unless the orifice and accumulator are less than 1 year old, I always recommend those parts be replaced if system is opened up and flush the system out. Overkill, sure, but it is my comfort zone and if someone wants me to stand behind a paid repair, that is what I did.

 

[mattbta]

@OR VietVet The shop that replaced my high side and then leaked out and needed a low side which they replaced said the only way to know if it was low on refrigerant would be to evac and weigh (thus incurring their service fee). I asked if they could just put gauges on it for a rough idea and the balked. What if I get those gauges you recommended in my thread -- would that be enough to know if it was out of spec?

 

[OR VietVet]

@OR VietVet The shop that replaced my high side and then leaked out and needed a low side which they replaced said the only way to know if it was low on refrigerant would be to evac and weigh (thus incurring their service fee). I asked if they could just put gauges on it for a rough idea and the balked. What if I get those gauges you recommended in my thread -- would that be enough to know if it was out of spec?

Gauges give you pressure readings, ambient temperature sensitive, of the refrigerant in the system, at static and also while the system is working and cycling. The only true way to know if you have too much or too little refrigerant in the system is to weigh it and monitor it during the charging process. A shop will balk at just a simple, "top off" because, IMO, 2 things. To top off can still either undercharge or overcharge the system and that can effect the efficiency of the system and can also do internal damage. Then when the shop accepts money for that process, you want to hold them liable. Also, to just top off the system, does not allow the tech to remove all moisture that could be in the system. When an a/c system is put in a vacuum, moisture will boil internally and the vacuum pump then removes that moisture as a gas. The longer it is on a vacuum pump, the more moisture is removed.

If I ran a shop, and when I did run shops, if the accumulator was at least 1 year old, I insisted on replacing it. It is the moisture filter for the system. Moisture does damage to the internal workings of the system. If the customer refused the replacement, I made sure there was a disclaimer on the work order and signed by the customer. You have to remember that I came from a hot and humid climate in KC, Mo., to the PNW. Not as much a/c work here in the PNW but gobs of it in KC, Mo. There was a time, during the changeover from R12 to R134A refrigerant, that I had backup gauges for both systems because I could not take a chance of not having the correct equipment for the a/c work I did and the shop did. Because an a/c machine is typically used by multiple techs and therefore more chances of machine abuse, I kept and used my own gauges and vacuum pump and flush equipment.

 

[03catburban]

How often does this pressure switch fail? I'll order 20 pieces right away...

No seriously, in all my years as a car technician I've definitely had 2 faulty pressure switches, but 20 faulty air conditioning condensers, 5 faulty compressors, faulty lines, leaks, electronic problems and so on.

And if your pressure switch is leaking, you don't know what amount of cooling refrigerant is left in the system, so when you do it in the right way, you have to evacuate the system, measure the amount of cooling refrigerant, set the system to vacuum, to remove humidity and refill the system again, what an automated air conditioning service system, what I have in my garage, all do automatically.

So I really wonder, why the manufacturer build in this valve, which has absolutely no sense.

But if they have it.. Great ...

I have dozens of them over my career not just gm but mainly domestics

And i agree on recovery so you know how much is lost. But some people just want the a/c working on their box, nevermind the car is falling apart, so being flat rate I'd change switch on top off via pressures. Instead of not getting the job at all

And your doing good with 5 faulty compressors as a tech I know I've replaced over 100, may be my geography

 

[OR VietVet]

I have dozens of them over my career not just gm but mainly domestics

And i agree on recovery so you know how much is lost. But some people just want the a/c working on their box, nevermind the car is falling apart, so being flat rate I'd change switch on top off via pressures. Instead of not getting the job at all

And your doing good with 5 faulty compressors as a tech I know I've replaced over 100, may be my geography

Yep, the heat and humidity in Georgia keeps the a/c compressors hummin'.

 

[Blk00ss]

I have removed and replaced switches at the accumulator without evacuating the system. Unless the design has changed.

I have as well. In fact, I changed the switch on this one a while back. But I can see dye around it which leads me to bleieve its a slow leak from there

And yes, I also can see now that there is in fact a scrader valve behind the switch. Now I gotta find a PN for it