I have a 91 Z28 with dual fans. They do not appear to work. I believe one is supposed to be on all the time and the other activates when the care warms up. Neither of them come on either way. Is there a sensor to check? And where is it? Thanks for the help!

 

One fan should not be on all the time. The primary is controlled by the computer and the secondary is controlled by a temp switch that should be in the pass. side head between the rear two plugs. I have seen these be disconnected a few times for reasons beyond me. Check to see if that one is connected. There is a CTS (coolant temp sensor) located at the front of the intake manifold. It may be hard to see with all the stock hoses and stuff, but it is there. I is a two wire sensor.

Do the fans work when you turn on the AC?

Also, are you sure they are not working. The secondary fan switch may not turn the fan on until about 225-230*.

You could check the relays for the fans, they should be on a bracket on the firewall, drivers side. If you are getting up to operating temp and the fan/fans are not coming on you could tap the motor gently with a hammer to see if that makes them work, sometimes with age the motor sticks...Hope this is helpful...

 

I had check both of the sensors, they seem good. Also, they do not go on when I turn on the AC. Oh, and when is the first on suppossed to go on?

 

I don't remember the exact temp the computer is programmed to turn on the primary fan. My stock 305 .bin from my 92 orginally had the primary fan set to come on at 108*C. That is about 228*F if I converted correctly in my head. These engine do run warm.

Since you said they don't go on with the AC, I would try and turn the engine on, turn on the AC and tap the motors. You would also want to use a test light or DVM to ensure you are getting voltage. If no voltage, I would look at the relays, fuses, and wiring. If you are getting voltage, I would condemn the motors.

 

Well, I tested the fans. They work. I'm not sure where the relays are though? What do they look like? Also, do you think the other sensors that you had mentioned might be bad? Thanks!

 

Fan relay is mounted on the right hand fender well near the battery and overflow tank.

The Trickster!!!!!!!!!!!

 

ON my 92 Z28 the fan relays are located on the firewall next to the brake booster. They look like black boxes with big four or five wire input plugs.

How did you test the fans? Did you tap the motors when they should be coming on? Did you unplug them and jump them to the battery?

 

Yeah, jumped em straight to the battery. How can I tell if the relays are bad?

 

Well, sometimes you can tap on them if they are stuck, but that doesn't always work. Since they are not expensive you could just buy a new one and try it. Or you could swap a relay that is known to be good. Use a wiring diagram to ensure that all the wiring is okay and that it is getting power and a switch signal. If you don't have a wiring diagram and/or DVM, just swap in a new or known good relay for one of them and see what happens. If it turns out not to be a relay, I am sure you can return it...Good luck.

 

There are three relays near the master cylinder. Do you know which is for the fan?

 

Two of the relays are for the fans, one for each fan. And the other is for the fuel pump. I cannot tell you which is which right now, but I will look in my Chilton manual and see if it says which is for what. If you have a chassis wiring diagram, then you could figure it out yourself by wire color. Or you could pull out each fuse one at a time and see when the fuel pump stops priming with the key on. Then the other two are for the fans. Good luck, I'll post later if I find which relay is for which fan...

 

Thanks for the help, but I swapped all three with the relays from a junk Camaro I have in my garage. No good. This is becoming a big pain in the ***!

 

Now its time to break out your DVM and start checking for power and grounds. I know tracking down electrical problems can be very tedious work, but if you approach from a systematic point of view and are careful to go step by step from point A to point B, you should be able to find your problem. Yeah, easier said than done, I know!!

BTW, don't overlook or assume anything, check it all...

 

crap...

 

i just went through the whole ordeal this summer. the previous owner hacked up all the wiring and made it so that both fans were on all the time, he even melted and broke all the connectors which cost me $50 each side just to get a new one. anyways here's the diagram that i went by to help me solve the wiring problems, hopefully this will help you out some

 

i just went through the whole ordeal this summer. the previous owner hacked up all the wiring and made it so that both fans were on all the time, he even melted and broke all the connectors which cost me $50 each side just to get a new one. anyways here's the diagram that i went by to help me solve the wiring problems, hopefully this will help you out some

 

Hey, that's cool! That should come in handy! I'm gonna try it out when I get home. Thanks!

 

OKay, I got sick of playing around. I rigged the primary fan to come on when the car was turned on and the secondary to a switch. Works good! Thanks for the help, though! As always your help is greatly appreciated!

 

I did the same to my car.
I ran mine using a gound wire from the chassis to my switches and then to the 2 relays. This is the best way to run the fans since the only thing I did was add 2 ground wires and 2 switches, original wires are still there and hooked up and un-modified.

 

What's the other switch for?

 

It's for nothing yet. I may use it to arm the Nitrous.