that switch is a combo low pressure/high pressure switch -- so it's probably fine -- no need to replace unless you verify via high and low side pressures that the system is sufficiently charged ---

which me thinks it is not.

good to know the compressor turns on.

 

Again sort of echoing the concern of looking up the same information repetively and cut and pasteing or typing it out.
I have a problem with using the defroster setting to determine if the compressor is kicking on and off.
1. I personally do not know if using the defroster actually turns on the A/C compressor although in theory I do know it is effective if done. Which does not mean it is done.
2. If I wanted the A/C compressor to turn on and off I would use the A/C switch to turn it on and off.
Why?
Because I do know that is how it operates. And that is what the switch is for.
And frankly I have owned cars where turning on the Defroster did NOT turn on the compressor, so it is a variable. One that is in my mind unpredictable as to how it runs so I personally can not in all honesty answer what should happen using the Defroster setting as a diagnostic with out ----
Looking up in my service literature that I paid damned good money to own so that I can both do it my self successfully OR help some one else out.
Secondly, why are parts being bought to fix an A/C unit with out first making some kind of a measurement to determine if they are needed or not?
No, you probably do not have a set of A/C unit gauges
or the instructions on how to use them.
I recognise that. Neither do I.
But
I do have the $20.00 some odd or so, replacement can of R-134 that comes with a hose and a guage that I use frequently to make a high pressure line measurements. It is plastic, cheap and I have broken 2 of them and am on my 3rd one in use over the last 10 years. It serves two functions. It gives me a pressure line measurement IF I read the instructions that came with it that says Red is bad and Green is good and make sure you keep in mind the temperature of the weather when you make the measurement. And if you are low on R-134, you can add some to bring it up to snuff. I use the hell out of it on my CARS, yes plural. And repairing others. And knowing what the pressure is answers the question of:
Is it low
which then defines what to do next. So I don't spend money I don't need to spend.
Is it perfect? NO! But it gets the job done.
If the pressure is low then that needs to be identified as to why and then needs to be repaired FIRST.
Of course the compressor motor has to run to make the measurement.
How is that done?
Turn on the A/C.
So here is my suggestion. Right or wrong when broken these computor controlled cars are complex and require a working knowledge of how it works and what to do to keep from spending money on things that are not broken.
For this a manual is required. While I own Factory Service manuals for many of my cars, for my Saturn I do not.
A Mitchels, Chiltons or many others while some times incomplete has been adequate to use. So Far.
A bloody good expenditure of about $25.00 or so
and as to things like making measurements before buying parts, yes not everyone is fortunate to have the tools or the knowledge to be able to do that. But a little reading and a cheap substitute can work well.
Harbor Freight sells a Digital Voltmeter that is adequate for $2.00 on sale, about $9.00 regularly. It works as well as my $450.00 meter for most things.
And my can of R-134 with a hose and a guage lets me diagnose any A/C problem I have had in the last 10 years since the change over from freon.
As to the rest of your problem, it may be related to the sensor refered to. It most commonly seems to be. The early Saturn S series engines had two of the. One that monitored engine temperature for the purpose of the computor displaying the temperature at the gauge on the dasboard and the second for determining how to run the engine depending on the temperature of it.
The later engines incorporated both functions into the one sensor as the computor determined it.
A number of wierd symptoms can be attributed to the both the original sensor being wrong and the replacements along with a high failure rate of them.
The problem today is finding a correct sensor and where now that there is NO Saturn dealers any longer.
This means either finding a GM dealer that will order you both the sensor and the repair kit for the wiring (also a problem prone part) or gambling that what ever parts place you buy parts from actually has the corrected part in their stock. Why corrected? Because it was wrong from the Factory for a long time and went un-identified which lead to parts houses making and stocking a replacement part that was also wrong.
Today, long afterwords, it is difficult if not impossible to determine what you are holding in your hand actually is proper one unless it is purchased from a dealer, of which there aren't any of.
So, one solution is simply a good sensor that is incorrect has to work better than a bad sensor that is incorrect.
And it sounds like you have a bad sensor. One that is in failure mode.
Your choice as to how to go about repairing things.
Here is my suggestion there.
Find a dealer that will order you a sensor. It is located on the end of the cylinder head on the drivers side of the car.
Buy it and install it to see if it will fix anything.
If you can't find a dealer try NAPA or CARQUEST for a sensor gamble it will either be the corrected right sensor or an incorrect sensor that is not broken. Either should work better than what appears to be a broken one of any kind from your description of what is going on.
And buy a manual.

 

Thanks so very much for your very detailed effort to help me, I was able to order a new pressure switch from a G.M. dealer and it should be in on Tuesday.I have a friend and neighbor who has a older Saturn who allowed me to try his switch off his car and it made no difference when I tried his on my car .Same thing though when I take the switch off the high side line and Jump it out the compressor does start up .I am a master senior Refrigeration Tech with Carrier Corp. so I do have all the various Refrigeration guages and a few different types of gasses to go with the trade,I recovered all the gas out of the unit and brought it into a 300 micron negative state ,more than enough for such a small system.I then allowed it stand and it did not climb above that.I did not previously fill system with dry nitrogen since the system did not seam to have any leaks. I filled with HFC (R-134A) and weighed in the proper charge of 1.5 lbs . Funny thing though is when the car has been in my garage with the salamander heater running and I try to start the car and then turn on the A/C switch it has engaged the compressor,so I am scratching my bald head on this one.I do have a (609) auto refrigeration certification but I only obtained that because it was convenient while I was in school.Really not a big thing though.So again thanks for trying to help me.I'll keep you posted with my results.

 

Quote
Funny thing though is when the car has been in my garage with the salamander heater running and I try to start the car and then turn on the A/C switch it has engaged the compressor,so I am scratching my bald head on this
UnQuote.
A little bell is going off when I read this. It is telling me that something more current with A/C on it than all but my Chrysler which I bought new in 2007 in my stable isn't has a temperature sensor in it some where that keeps the A/C from functioning if the outside temperature is too low which prevents damage from taking place if the compressor kicks on when it is flat too cold and it should never run.

What is too Cold. Well here it is the 2nd week in February and it is 5:30AM and it is 52 degrees where I live, and yesterday on the way to the monthly meeting of the AMC club dinner it was 80.
The part of the country I grew up in, this was the dog days of August Temperature and is what we call here laughingly ------winter.
If you have to run a Salamander, the odds are where you live?
It might be too cold.