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 MANUALSCHEVROLET1990BLAZER FULL SIZE V8-350 5.7LREPAIR AND DIAGNOSISHEATING AND AIR CONDITIONINGTESTING AND INSPECTIONCOMPONENT TESTS AND GENERAL DIAGNOSTICSFUNCTIONAL TEST/CHECKFUNCTIONAL TEST
1990 Chevrolet Blazer Full Size V8-350 5.7L
Functional Test
1990 Chevrolet Blazer Full Size V8-350 5.7LSECTION Functional Test
Use the following Cycling Clutch Orifice Tube (CCOT) "Hand-Feel" procedure if the A/C system has the proper charge of Refrigerant-12 (providing ambient temperature is above 21°C (70°F).
1. Engine must be warm (CHOKE OPEN and OFF FAST IDLE SPEED CAM) and at normal idle speed. Diesel engine at normal idle.
2. Hood and body doors open.
3. Selector (mode) lever set at NORM.
4. Temperature lever at COLD.
5. Blower on HI.
6. "Hand-Feel" the temperature of the evaporator inlet pipe after the orifice and accumulator with the compressor engaged.
- BOTH THE SAME TEMPERATURE AND SOME DEGREE COOLER THAN AMBIENT-Proper condition: check for other problems.
- INLET PIPE COOLER than accumulator surface indicates a low refrigerant charge.
^ Add amounts 120 ml (4 ounces) of refrigerant UNTIL BOTH feel the same temperature. Allow stabilization time between additions.
^ Then add 420 ml (14 oz.) one can additional refrigerant. The 420 ml (14 oz.) disposable can of Refrigerant-12 is the equivalent to .88 lbs..Testing and Inspection
1. Engine must be warm (CHOKE OPEN and OFF FAST IDLE SPEED CAM) and at normal idle speed. Diesel engine at normal idle.
2. Hood and body doors open.
3. Selector (mode) lever set at NORM.
4. Temperature lever at COLD.
5. Blower on HI.
6. "Hand-Feel" the temperature of the evaporator inlet pipe after the orifice and accumulator with the compressor engaged.
- BOTH THE SAME TEMPERATURE AND SOME DEGREE COOLER THAN AMBIENT-Proper condition: check for other problems.
- INLET PIPE COOLER than accumulator surface indicates a low refrigerant charge.
^ Add amounts 120 ml (4 ounces) of refrigerant UNTIL BOTH feel the same temperature. Allow stabilization time between additions.
^ Then add 420 ml (14 oz.) one can additional refrigerant. The 420 ml (14 oz.) disposable can of Refrigerant-12 is the equivalent to .88 lbs..Testing and Inspection
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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.