No electrical power to AC Compressor. The switch light comes on in car when AC power button is turned on.

In a 1994 Chevy K1500, the compressor should receive power when the AC button is turned on, assuming that the system is adequately pressurized and there are no other issues preventing it from engaging. Here are some steps to diagnose the issue:

1. Check Refrigerant Levels: Low refrigerant levels can prevent the AC compressor from engaging. If your system is low on refrigerant, it may need to be recharged. This is typically a job for a qualified technician.
2. Check for Refrigerant Leaks: If your system is low on refrigerant, it's essential to check for leaks. A leak can cause the refrigerant to escape and prevent the compressor from engaging. Look for signs of oil or refrigerant leaks around the AC components.
3. Fuse and Relay Inspection: Ensure that the AC system's fuse and relay are functioning correctly. You can consult your vehicle's owner's manual or a fuse box diagram to locate the relevant fuses and relays. Replace any blown fuses or faulty relays.
4. Check the Pressure Switch: Many vehicles have a high-pressure and low-pressure switch in the AC system. These switches monitor the pressure in the system and can prevent the compressor from engaging if the pressure is too high or too low. Check these switches for proper operation and continuity.
5. Inspect Wiring and Connectors: Examine the wiring and connectors leading to the AC compressor. Look for damaged wires, loose connections, or corrosion. Ensure that there is no damage to the wiring harness.
6. AC Clutch and Compressor: If all the electrical components are working correctly, you may need to inspect the AC clutch and compressor itself. The AC clutch should engage and disengage when the AC is turned on and off. If the clutch isn't engaging, it may be faulty, or there could be an issue with the compressor itself.
7. Refrigerant Pressure Sensors: Some vehicles are equipped with refrigerant pressure sensors that can prevent the compressor from engaging if the pressure is out of the specified range. Check if your vehicle has such sensors and test them if necessary.
8. Professional Diagnosis: If you've checked all of the above and cannot identify the issue, or if you're uncomfortable working on AC systems, it's recommended to consult a qualified automotive technician or AC specialist for a thorough diagnosis and repair.

Remember to prioritize safety when working on your vehicle's AC system, as it involves high-pressure refrigerant and electrical components. If you're not experienced in automotive AC repairs, it's best to seek professional assistance to avoid injury or damage to your vehicle.

A/C compressor clutch relay , the PCM/ECM isn't energizing it ? Do you know what a wiring diagram is ? How to test electrical circuit's with a volt meter ? Free wiring diagrams here http://www.bbbind.com/free-tsb Enter vehicle info. year , make , model an engine . Under system click on HVAC ,then under subsystem click HVAC controls . Click the search button then the second blue link. Compressor clutch relay circuit .

disconnect the wire at the compressor to check that the clutch is releasing,then with a test light check to see if power is present when it is switched on and no power when off.

Do you know how to do electrical testing using a DVOM - digital volt ohm meter ? How to use a wiring diagram to find test point's in a electrical circuit ? This how we find an fix electrical problems on automobiles .
Electric Testing Techniques You Need to Know

can it be the starter ignition switch?? Guessing is not the way to a fix . TESTING is !!!! Maybe you fried the PCM - engine computer !

http://www.bbbind.com/free_tsb.html free wiring diagrams . Enter your vehicle info. year , make , model an engine size... Under system click on electrical distribution , then under subsystem click on power distribution . Click the search button .Then click on the blue links one at a time . Take your volt meter an check for B+ voltage into the ignition switch then in start test for B+ voltage out . And if you don't know how to test like this ,your best bet would be to take your vehicle to a qualified repair shop that does !

I would guess a loose electrical connection. Have you had work done lately?

this electric problem , check A/c main S.w, if you wont make sure
check the compressor main electric power line ,

If the compressor came on when you were testing it with a test light, it sounds like something is wrong with your ground for your compressor, and completely the circuit through your test light.

the compressor is also controled by the coimputer. Disconnect the battery than reconnect it than try your ac to see if it comes on. if it does and it clicks on and off than you may be low on freon. Being low on freon will also keep the compressor from coming on because you have pressure switches that are in ac lines that control power to the compressor. you can disconnect the wires at the compressor and with the car running turn the ac on and probe the wire with a test light to see if you have power to the compressor. If you have power than chances are your ac clutch may be bad. Hope this helps leave a comment.

could be AC compressor clutch shorting out.try disconnecting AC compressor electrical connector and see if fuse still blows.

The A/C pressure switch is located in the high pressure line (the skinny one) on the passenger side of the engine compartment just under the fuse/relay box. The switch has three functions: <28 psi, the switch opens to protect the compressor from lack of lubrication. >220 psi, the switch shifts the radiator and compressor fan to high speed. >455 psi, the switch opens to protect the compressor seals. Check to see if you have any powertrain DTC's first. A faulty engine coolant temp sensor can cause problems with the compressor clutch relay. If the radiator and compressor fan come on with the A/C on but the compressor clutch does not operate, check the compressor clutch relay. You can also obtain Heater control panel diagnostic trouble codes (DTC's) by turning the ignition switch on. Then turn fan switch off. Press recirc button to select recirc air. Press and hold recirc to turn off recirc air but this time continue to hold the button down until recirc light comes on for two seconds and then goes off. If there is any trouble, the recirc light will then blink a code (if no trouble, the light will remain off) 1 blink = problem in air mix control motor circuit. 2 blinks = a problem in mode control motor circuit. 3 blinks = a problem in evaporator temperature sensor circuit. (this one could be a factor in your case) Turn the ignition switch off to end the test.