Ok here goes it. When I hook the can with gauge up to the low side and pull the trigger and then let go I get a reading. Its 45. I started at about 5 with no reaction from compressor but after about two minutes its now reading the 45. Now compressor is short cycling, but heres the money question. While the guage is connected it will read 45, but when the compressor kicks on, it drops down significantly. Which reading should I be paying attention to. I feel like I need to keep adding until the reading is 45 when the compressor stays on. Is this correct. My theory here, is that the sensor is viewing that there if freon, enough to turn on, but now I have just reached the level where it will short cycle.

Also, is there a way to bypass the sensor temporarily in order to keep the compressor running?

Any help is appreciated, I'm tired of sitting in my truck sweating.

The pressure that matters is where the low pressure goes to when the compressor is running. It will need to continue to run until you have pulled in enough refrigerant at which time the "SHORT" cycling will have lengthened out. Putting the can of refrigerant into a can of hot water will speed up things. And you should not be looking for 45 psi on the low side. I'd start measuring vent temps and monitor them. Add refrigerant until your clutch is not SHORT cycling but is still cycling once or twice a minute at 75-80 degrees F ambient, less often if warmer... it will also help if you put a fan in front of the condensor.

It might help explain this a little better if you read the thread up at the top of this forum "Recharging your AC A-Z".

Thanks for the reply. The can is so adamant about not exceeding 45psi, I was afraid to go beyond. But it makes sense to only worry about the number that registers when the compressor is running. Thanks again.

I just noticed your model year. I assume your system has been previously converted from R-12 to R-134?

Yes it had been when I bought it. I notice that when I remove the can form the low side, I can hear it leaking from the schrader valve. The cap has a seal and if I put it on tightly it stops, but is there a way to change out the valve without evacuating the whole system. I know they make something for home ac's that does thee trick.

Assuming your system was an R12 with a R134a valve adapter, it will look similar to the picture in the first attachment. The silver fitting is the adapter. It contains a schraeder valve extension that sets on the actual schraeder valve on the accumulator. When I got mine the extension was to low in the adapter. When I screwed it in, it engaed the schraeder valve.
In the second attachment, is the schraeder valve adapter adjustment tool (made from drill bit and Dremel tool), this fits over the adapter and unscrewed it a couple threads until it no longer leaked when installed. I tried a regular scraeder valve adjustment tool from O'Relly ($3.00) but it didn't fit for some reason.
Remove the adapter and see if you still hear the leak. If you do it's the schraeder valve, which must be removed or lived with (keep the cap on tight). If the leak stops adjust the extension with the tool through trial and error.
WEAR GOGGLES! This stuff is injurious.
The valve adapter is not supposed to be removable (loctite) but mine goes on and off easily. You can adjust the adapter while on the valve but you are guessing its the adapter and not the valve itself leaking.
Did I mention WEAR GOGGLES!
Good luck

I'll give it a go. I think its the adapter that came with the kit. It looks just like yours. For now I think the cap is working, but I will open it up tonight and see if I can adjust. Thanks for the input.

They DO make tools that remove a valve core without discharging the system, and also allow you to replace it... in this photograph, the top mopst tool is that tool, the bottom is for use on a discharged system

http://www.explorerforum.com/data/2/medium/15286Dscn4661.jpg

This tool screws onto a fitting though and was designed for R-12 and R-22 systems. I am unaware of one made for 134 systems, but I am not saying it might not exist.