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Low pressure switch

how do i change the low pressure switch for the ac on a 2000 blazer

It should be the pressure switch in the accumulator, The big can looking thing near the passenger side firewall. There is a Schroeder valve underneath to prevent refrigerant loss when removed. Just disconnect the wires, unscrew the switch, and screw the new one on. Reconnect the wires once secured.

BTW, are you sure it is the switch? Are the pressures in the system good? The switch is a simple on/off switch, so checking it in place with a multimeter before replacing it is recommended. At rest, most A/C system equalize to about 70-100 psi on both high-side and low-side. Plenty of pressure to keep that switch on. Once running, if the compressor is cycling, this is an indication of low pressure on the low-side, meaning loss of refrigerant.

i had the swtich checked, and it is bad…so i bought the replacement…the problem im having is the new one is not made like the old one…i unscrewed the old one from the big can looking thing, but the new one does not have a nut like with threads to screw it on…its a flat surface…so i cant put the new one on…i need help…louisiana summers are brutal…thanks M.

They gave you the wrong switch. Take it back, and have the bad one with you to match up. These switches were used for many years in all kinds of GM cars and trucks, going back to the mid-80s, so they should have the correct one they can swap out for you.