Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSGMC1995SUBURBAN K2500, 7.4 NREPAIR AND DIAGNOSIS (SINGLE PAGE)HEATING, VENTILATION & A/C (HVAC)HVAC CONTROL SYSTEMSA/C SYSTEM DIAGNOSIS - MANUALTROUBLE SHOOTINGA/C COMPRESSOR INOPERATIVE
1995 GMC Suburban K2500, 7.4 N
A/C Compressor Inoperative
1995 GMC Suburban K2500, 7.4 NSECTION A/C Compressor Inoperative
NOTE:
To properly diagnose system, outside temperature must be greater than 60°F (16°C).
- Turn ignition on. Place blower switch in HI position. Using DVOM, measure voltage at A/C-heater control module connector Light Green wire. If voltage is not present, go to next step. If battery voltage is present, go to step 3).
- Using DVOM, check continuity of White wire between A/C-heater control module connector and ground. If continuity exists, replace A/C-heater control module. If continuity does not exist, repair open White wire between A/C-heater control module connector and ground. If wire is okay, replace water valve.
- Using DVOM, measure voltage at A/C compressor clutch relay connector Light Green wire (located under instrument panel, on A/C-heater assembly case). If battery voltage is present, go to next step. If voltage is not present, repair open Light Green wire between A/C compressor clutch relay connector and A/C-heater control module connector.
- Using DVOM, check continuity of Black wire between A/C compressor clutch relay connector and ground. If continuity exists, go to next step. If continuity does not exist, repair open Black wire between A/C compressor clutch relay connector and ground.
- Check continuity of Light Blue wire between A/C compressor clutch relay connector and A/C high pressure cut-out switch connector (located at right front side of engine compartment). If continuity exists, go to next step. If continuity does not exist, repair open Light Blue wire between A/C compressor clutch relay connector and A/C high pressure cut-out switch connector.
- Check continuity of Dark Green wire between A/C compressor clutch connector and A/C high pressure cut-out switch connector. If continuity exists, go to next step. If continuity does not exist, repair open Dark Green wire between A/C compressor clutch connector and A/C high pressure cut-out switch connector.
- Check continuity of Black wire between A/C compressor clutch connector and ground. If continuity exists, go to next step. If continuity does not exist, repair open Black wire between A/C compressor clutch connector and ground.
- Check continuity between A/C compressor clutch terminals. If continuity exists, replace A/C compressor clutch relay. If continuity does not exist, replace A/C compressor clutch.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.