For 1990-2009 cars

Complaint/Condition | Possible Cause(s) | Correction(s)
--- | --- | ---
Engine Overheats | System low on coolant. | Replenish coolant and check for leaks.
| Dirt, leaves, or insects on radiator or condenser. | Clean radiator and/or condenser.
| Hoses, water pump, thermostat housing, radiator, core plugs, or head gasket leakage. | Repair as necessary.
| Thermostat damaged.* | Check thermostat.*
| Incorrect ignition timing. | Check and correct timing malfunction.
| Electric cooling fan not functioning properly. | Inspect electric cooling fan motors and fan relay module.
| Radiator hose plugged or rotted. | Replace radiator hose.
| Water pump damaged. | Replace water pump.
| Radiator plugged. | Inspect, clean, and/or replace radiator.
| Coolant pressure cap damaged. | Inspect, test, and/or replace coolant pressure cap.
| Restricted or plugged exhaust. | Check for damaged or plugged exhaust.
| Cylinder head or block cracked or water passage(s) plugged. | Repair as necessary.
| Accessory drive belt and/or tensioner. | Inspect and replace as necessary.
| Plugged heater core. | Repair as necessary.
| Plugged heater hose. | Check heater inlet, and outlet hoses.
| Coolant solution. | Check protection.
| A/C pressure transducer or engine coolant temperature sensor not functioning properly. | Verify proper operation of transducer or temperature sensor. (Refer to "Diagnostic Charts" in this service manual.)
Coolant Loss | Check coolant pressure cap. | Replace if necessary.
| Leaks: Check hoses, radiator clamps, water pump, thermostat housing, radiator drain valve, soft or core plugs, heater core, and surge tank low level sensor. | Repair if necessary.
Oil in Coolant | Automatic transaxle oil cooler in radiator. | Repair as necessary.
| Cylinder head gasket. | Repair as necessary.
| Cylinder block/head casting porosity. | Repair as necessary.
No Heat From Heater | Foaming coolant observation in surge tank after engine warm-up. | Pressure check system by installing pressure tester on surge tank fill neck and checking pressure cap. Also, check hoses, clamps, filler neck, etc., for obstructions or plugging in the hose between the cylinder head, heater core, surge tank, and thermostat housing.
| Thermostat damaged.* | Inspect thermostat.*
| Water pump seized or defective. | Inspect water pump.
| System low on coolant. | Replenish coolant and check for leaks.
| Heater core or hoses. | Check for coolant flow through heater. Repair as necessary.
| Low coolant volume. | Check coolant level.
| Auxilary coolant pump inoperative. | Inspect auxilary coolant pump electrical circuits. Pump will not operate if circuits are reversed. Check for flow from pump at heater core inlet.
Engine Cooling Fans Inoperative On Any Speed | Engine cooling fan circuit | Reference Cooling Fan Schematics

* If the engine tends to overheat, removal of the thermostat will adversely affect cooling efficiency.

• | Determine the cause for oil in cooling system.

• | Flush cooling system as following the instructions in the cooling section of the manual.

• | Replace thermostat cartridge.

• | Fill cooling system with a 50/50 solution of DEX-COOL® antifreeze and clean water.