I have an 86 iroc with a single fan set up.it is a 5.0 tpi motor. Form the second i start the car the fan runs.now the car wont come up to temp.the car always runs right at 180 to open the stat. What could be the problem? A short? Or the sensor went bad?

 

I aslo need to add as i drive the service light comes on. When i go to get the code nothing comss up cus the light goes off after turn the car off.it only comes on as i drive for about 5 miles or more.

 

Fan maybe hot wired by the PO, should come on when temp hits 227.

Or temp sensor or relay that kicks fan on is bad, usually works the other way and doesn't come on if switch is shot.


Engine light comes on ... code should be stored in computer.

Plug in code thing (or paper clip), turn key on(no start eng), fan should run, should flash a code 12 first to let you know computer is communicating .... do you get at least a 12 ?? (One blink, then two blinks)

 

The fans are one thing that need to be fixed but if you want to run it in the 200* or higher range than you can change the thermostat to a 195*.That's stock setting.

So its ‘still at 180* even in stop and go traffic? I would call around to different shops and ask if they will test the temp of your engine with an inferred temp. gun.(usually free) Compare that to your gage. It could be off. Any way running at 180* is not going to hurt the car especially if the temps get higher in traffic. The fan circuit should be looked at carefully because if its hard wired directly into a ignition circuit you need to install a relay and IMO a adjustable temp switch to fix the always on problem.

 

I remember back with my old '84 Z28 the fans would kick on after starting the car and wouldn't shut off even when I pulled the key out. Several occasions I had to pop the hood and disconnect the battery to get the fans to stop.


Now on my current '92 Z28 I experience a somewhat similar problem, but the fans stop when the engine is shut off. Even if I have the engine running for 3 minutes and temp gauge not showing full operating temp yet, the fans still run. After shutting the engine off then turning the key to the ON position, fans will again kick on.

My guess would be a bad relay (in both my cars), but I won't know until I try and replace it.

 

Its one of 3 problems. Relay is stuck, the sensor has went bad and stuck closed or it has been bypassed. I would check the wires at the relay and see if they have been jumped out?. If not you can replace the fan sensor. You can get two different sensors now. They make a 175° and the factory 220° sensor. I would recommend the 175° sensor as many heat issues as they had with these cars and vapor locking, but that's just my preference.
Hope this helps you.

 

Sounds like a stuck relay most likely. But check the wiring to see if the previous owner did anything that might cause it to always be on.

Like others said, could be the coolant temperature sensor, or the fan switch too.

Make sure when you're replacing the parts, use good quality parts, preferrably AC Delco parts. I replaced two relays while troubleshooting a fan problem, and I got the relays from OReilly's. Well, within a few months I have a problem with my car only starting 1/5 times. I wasted about $300 and a lot of time, just to find out it was the brand new relay that went bad. 6 months later, the fan relay eventually goes bad. I replaced them both with AC Delco relays and haven't had a problem since.

 

What caused the car to start 1/5 times?

 

The fan has nothing to do with it not starting.

 

Yeah I know the fan has nothing to do with the car starting, I was just trying to stress that you need to make sure to get good quality parts.

I had replaced the fuel pump relay and the cooling fan relay with parts from OReilly. They both went bad. One went bad within a few months, the other went bad after 6 months.

It was the fuel pump relay I bought from OReilly's. It was probably sticking or something, I'm not sure.

 

Yep. I agree with you. You get what you pay for when it comes to parts. If its a GM product run Delco. Anything
Else just won't hold up to how GM has designed them. not to mention most parts are coming from China and other forien countries!