2003 Trailblazer AC problem

Having an on again/off again problem with 2003 Trailblazer LTZ with the electronic AC control.
Just recently has started blowing non-cooled outside air all at once. Have
found if I turn compressor switch to OFF then ON again, the cooling sometimes comes back.
Chevy dealer says must leave for day so technician can drive until it fails (which it doesn't always do!) and that procedure is at their "hourly" rate.
Is the switch possibly corroded or something to just spontaneously make the compressor shut down?
Thanks for any help/suggestions
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Found GM Service Bulletin # 03D-J-128 which ID's a probable cause to be the Low Pressure Cycling Switch. Trying to pin it down now.
If this is ID'd as being the cause, it looks like a simple replacement job. My question is, when I remove the old switch will I lose Gas? If so, will use the dealer who will probably turn a 10 minute operation into a 10 hour diagnostic marathon at a bunch-of-bucks per hour rate!
Thanks for any help you can give!
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It isn't a 10 minute operation as the system will have to be purged and then filled. Get an estimate from the dealer and several good independent AC shops.

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Woody,
Thanks for advice. Was afraid this might be the case. Why can nothing be simple?
Appreciate the help much!
Tom

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I "think" that the switch can be replaced without losing any refrigerant. My experience is that these switches are screwed on to a Schrader type valve. The valve closes off when the switch is unscrewed. The experts on here can jump in and correct me if I'm wrong.

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Thanks for the info, Silver Surfer.
Anyone out there sure before I blow my gas all over the garage? It's a 2003 Trailblazer LTZ if that's of any help. Read somewhere else that when unscrewing you should hear a short "hiss" then the valve closes. Right now I'm chicken to try it without some reasonably sure advice.
Any input would be most appreciated!
Tom

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For what it's worth the service manual makes absolutely no mention of having to remove the refrigerant charge when replacing the pressure switch. Procedure below:
Document ID# 777012 2003 Chevrolet TrailBlazer - 2WD -------------------------------------------------------------------------------- Air Conditioning (A/C) Low Pressure Switch Replacement Tools Required J 39400-A Halogen Leak Detector
Removal Procedure Disconnect the A/C low pressure switch electrical connector. Remove the A/C low pressure switch (2) from the accumulator (1). Remove and discard the O-ring seal from the A/C low pressure switch port on the accumulator.
Installation Procedure Install the new O-ring seal. Refer to O-Ring Replacement .
Notice Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Install the A/C low pressure switch (2) to the accumulator (1). Tighten Tighten the A/C low pressure switch to 4.8 Nm (42 lb in).
Connect the A/C low pressure switch electrical connector. Leak test the fittings of the components using the J 39400-A .

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Really appreciate the good advice and forwarding the Service Manual information. Will pick up new switch and install tomorrow.
Will certainly let you know if I did good or not!
I'm retired now (age 70) and just don't have the money that shops seem to want a get for out-of-warranty work. I notice that service in warranty is quick and service out of warranty is not so quick and requires many many parts!
Thanks again for your help, friend.
Tom

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