radiator cooling fan not working?

1998 CHEVROLET CAVALIER
120,000 MILES • 4 CYL • FWD • AUTOMATIC
Avatar
SHERRYRENEE
  • MEMBER
  • 6 POSTS
I have a 98 chevy cavalier z24 2.4 litre. I have replaced all sensors and flushed the radiator, bought a new resevoir, replaced therm. fan relay and my fan won't click on when the temp. gets hot. The only time my fan comes on is when my AC is on. When I turn my car off coolant comes out of the top of the resevoir thru my cap. I live in AZ and it is getting hotter. I need help. Any suggestions on what it could be. My car is overheating and getting horrible gas mileage.
Jun 10, 2008 at 9:56 PM
Advertisement
Avatar
RASMATAZ
  • CERTIFIED EXPERT
  • 75,992 POSTS
Coule be the computer. Double check the engine coolant temperature sensor also see below


https://www.2carpros.com/forum/automotive_pictures/12900_c1_6.jpg

Jun 11, 2008 at 1:36 AM
Avatar
SHERRYRENEE
  • MEMBER
  • 6 POSTS
I have changed the engine temp. control sensor. How can I find out if its in the computer?
Jun 11, 2008 at 7:00 AM
Advertisement
Avatar
RASMATAZ
  • CERTIFIED EXPERT
  • 75,992 POSTS
Check the CTS signal input to the computer see above
Jun 11, 2008 at 7:31 AM
Avatar
SHERRYRENEE
  • MEMBER
  • 6 POSTS
How would I go about checking the CTS signal to the computer? I have a data reader and when I plug it into my computer it don't have any problem codes.... Thank you so much for helping me with this problem.
Jun 14, 2008 at 10:44 AM
Avatar
RASMATAZ
  • CERTIFIED EXPERT
  • 75,992 POSTS
Disconnect the wire harness connector from the CTS and measure the resistance of the sensor with a high input impedance (digital) volt-ohmmeter. The resistance should be less than 1000 ohms with the engine warm


https://www.2carpros.com/forum/automotive_pictures/12900_0900823d8015231b_2.jpg

Jun 14, 2008 at 11:42 AM
Avatar
SHERRYRENEE
  • MEMBER
  • 6 POSTS
So if I do the testing and the reading is where it is suppsoe to be then how do I know if it is in my PCM. I just changed the ECT. So I am pretty sure that it is not faulty. I know that is how to test the ECT to check if its faulty but how do I check my puter to check if its bad???? Thank You for responding so quickly...
Jun 14, 2008 at 12:39 PM
Avatar
SHERRYRENEE
  • MEMBER
  • 6 POSTS
I have tested my ECT signal and it is working properly. I got a reading of 453 when it was at normal running temp., and it stated at 904. How do I test my computer now.
Jun 14, 2008 at 4:44 PM
Avatar
MERLIN2021
  • CERTIFIED EXPERT
  • 17,250 POSTS


https://www.2carpros.com/forum/automotive_pictures/62217_Fan_Relay_1.jpg


https://www.2carpros.com/forum/automotive_pictures/62217_Operationa_1.jpg


https://www.2carpros.com/forum/automotive_pictures/62217_Testsa_1.jpg


https://www.2carpros.com/forum/automotive_pictures/62217_Testsb_1.jpg


https://www.2carpros.com/forum/automotive_pictures/62217_Testsc_1.jpg


https://www.2carpros.com/forum/automotive_pictures/62217_Testsd_1.jpg


https://www.2carpros.com/forum/automotive_pictures/62217_WDa_1.jpg


https://www.2carpros.com/forum/automotive_pictures/62217_WDb_1.jpg


https://www.2carpros.com/forum/automotive_pictures/62217_WDc_1.jpg


https://www.2carpros.com/forum/automotive_pictures/62217_WDd_1.jpg

Jun 15, 2008 at 7:04 AM
Avatar
SHERRYRENEE
  • MEMBER
  • 6 POSTS
Thank you so much for all the information. After reading much of it I understand more why my fan won't click on. I guess engine temp isn't getting to 223 F. I am going to test everything you have sent me information on. I will get beck to you with the results. Again thank you so much for all the help.
Jun 15, 2008 at 9:02 AM
Avatar
MERLIN2021
  • CERTIFIED EXPERT
  • 17,250 POSTS
sure....
Jun 15, 2008 at 10:30 AM