GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Check the coolant for proper concentration level.

Is the coolant concentration level within specification?

--

Go to Step 3

Go to Step 2

2

  1. Drain the cooling system. Refer to Cooling System Draining and Filling .
  2. Flush the cooling system, if necessary. Refer to Flushing .
  3. Refill the cooling system with a 50/50 mixture of DEX-COOL® coolant and clean, drinkable water. Refer to Cooling System Draining and Filling .

Is the repair complete?

--

Go to Step 7

--

3

Check the thermostat to see if it is in a stuck open position.

Is the thermostat stuck open?

--

Go to Step 4

Go to Step 5

4

Replace the thermostat.

Is the repair complete?

--

Go to Step 7

--

5

Check the coolant level.

Is the coolant level below the add mark?

--

Go to Step 4

System OK

6

Add the coolant as necessary. Use the proper fluid. Refer to Fluid and Lubricant Recommendations in Maintenance and Lubrication.

Is the repair complete?

--

Go to Step 7

--

7

Verify proper system operation.

Is the engine slow to warm up, does not reach normal operating temperature or does not have enough heat?

--

Go to Step 1

System OK