Is this a bad thermostat or engine temperature gauge problem?

1990 NISSAN 300ZX
147,000 MILES
Avatar
WEVERETT
  • MEMBER
  • 2 POSTS
I have a 300ZX with 147,000 miles. When turning on the air conditioning, the engine temperature gauge rises to the top. When I turn off the air, the temp drops back to normal. Is this a bad thermostat or engine temperature gauge problem?
Jun 22, 2012 at 4:42 PM
Advertisement
Avatar
DOCFIXIT
  • CERTIFIED EXPERT
  • 18,828 POSTS
Suspect cooloing fan or radiator effeciency reduced to calcium buildup in core
Jun 22, 2012 at 4:47 PM
Avatar
KHLOW2008
  • CERTIFIED EXPERT
  • 41,814 POSTS
If the gauge shoots up immediately and cooling fans works, it would be an inaccurate reading due to a bad ground circuit connection, behind the headlights.
Jun 23, 2012 at 3:07 PM
Advertisement
Avatar
TIMHILLMER
  • MEMBER
  • 7 POSTS
most likely this would be caused by a bad ground connection.
Jul 15, 2012 at 9:28 PM
Avatar
WEVERETT
  • MEMBER
  • 2 POSTS
Thanks for help. Replaced clogged radiator, power washed the air conditioner condenser. I could not believe the road crud that washed out. While I was there I replaced the hoses and thermostat. To my surprise, the thermostat had been removed. There wasn't one. I bought this Z used. Previous owner must have had overheating issues as well. Not sure what fixed the problem ( maybe all of the above) but temp gauge is level no matter if air is on or not and it is 110 degrees out.
Jul 16, 2012 at 10:10 PM