Problem:Cooling Fan Inoperative - (Pages 12 and 13)626 Diesel

Test Conditions: (1) Key at "ON" (Engine off)
(2) Fan speed at "1"
(3) A/C switch "ON"

Important: (1) Compressor clutch should be engaged. If not, see compressor clutch inoperative before proceeding.
(2) The cooling fan should operate when both the A/C and fan switches are on.

WATER TEMPERATURE SWITCH CONNECTOR LOCATION:

Step 1. Disconnect the water temperature switch connector.

CHECKING RESULTS

A. If the fan operates, reconnect the water temperature switch connector and proceed to Step 3.

B. If the fan does not operate, reconnect the water temperature switch connector and proceed to Step 2.

COOLING FAN CONNECTOR:

Step 2. Check the yellow wire for power at the cooling fan connector.

CHECKING RESULTS

A. If power exists, repair or replace the cooling fan motor.

B. If no power exists, check the yellow wire for a loss of continuity between the 20 AMP fuse marked "Cooling Fan" and the cooling fan connector.

A/C RELAY CONNECTOR:

Step 3. Check the blue wire for power at the A/C relay connector.

CHECKING RESULTS

A. If no power exists, check the blue wire for a loss of continuity between the A/C switch connector and the A/C relay connector.

TROUBLESHOOTING THE A/C RELAY:

B. If power exists, follow the (3) steps below in order to troubleshoot the A/C relay.
(1) Remove A/C relay from connector.
(2) Apply 12 volts to terminals 1 & 2 as shown.
(3) Using OHM meter, check for continuity between terminals 3 & 4 as shown.
^ If continuity exists, reconnect the A/C relay and proceed to Step 4.
^ If no continuity exists, replace the relay.

YELLOW-GREEN WIRE, CHECK AT A/C RELAY:

Step 4. Check the yellow-green wire for power at the A/C relay connector

CHECKING RESULTS

A. If power exists, proceed to Step 5.

B. If no power exists, check the yellow-green wire for a loss of continuity between the cooling fan connector and the A/C relay connector.

BLACK AND BLUE-RED WIRE, GROUND AT A/C RELAY:

Step 5. Separately ground the black and blue-red wire at the A/C relay connector.

CHECKING RESULTS

A. If the cooling fan operates when the black wire is grounded, check it for a loss of continuity between ground and the A/C relay connector.

B. If the cooling fan operates when the blue-red wire is grounded, check it for a loss of continuity between the blower motor resistor and the A/C relay connector.