I have a 94 Z28 That I am doing some work on. I did the T-body by-pass and a new t-stat today and was bleeding the cooling system. Ok here is the question.....My temp gauge goes about 1/8 to 1/16" before the redredline on the gauge and then the fans come on.....seems too high so I look for a reason, well I only have 1 fan working. The drivers side fan works but the passenger side does not work...OK test, check for power to fan, nothing, check fuses ok, jump fan relay for right side fan-works. Hmm....Change relays, nothing happens fans still inop...Turn A/C on=both fans should come on right---NO!! still inop just the left fan working....Check power in PDC for relay have power to both sides of relay....Does anyone have a clue on what this could be??? Also how high should the temp gauge get before the first fan turns on, because mine gets almost to red then cools down about 1/2 way and thats the coolest it gets...Need some advise on where to go from here..thanks for any help...PS. I live in arizona and need my fans working correctly before summer.

 

First is to know is if you have the 2 or three fan relay system. Only the driver side fan initially comes on with the 2 relay system.

If you are getting power out of the relay to the fan and the fan is not working, then the wiring from the relay to the fan is bad, fan is unplugged or the fan is bad.

There is a fan schematic on my Tech Page as well as an explanation how the system works with the ON temps and such.

 

It's a 2 relay system and when I jump the right side fan it works. The problem is I never see it come on by itself and I think they both should work with the a/c on.......I am not sure though thats why im here asking people who know...

 

The stock programming in my 94 was 1st fan on at 226degF, 2nd fan on at 235degF.

 

I hate the way chevy did the temp gauge with not putting more temp # readings instead of lines......dumb question but how far up the gauge does your temp get before fan #1 comes on?

 

Both fans on with your system would be the equivalent to high speed on the 3 relay system and they don't come on at high speed when the a/c is turned on. I am reasonably certain that only the driver side fan will come on initially, even with the a/c.

Check for air again when the engine is at operating temp, because air pockets can cause the gauge to go way up.

 

If you read the cooling system operation stuff on my page, it explains some of that.

My fans are reprogrammed, but the middle of the gauge is 210º-220º. So the needle is most of the time past the middle before the fan(s) come on.

 

The car never really overheats as in losing coolant or steaming, on the freeway it runs just below the 1/2 way mark, but in traffic it gets to about 1/8-1/16" before red then the drivers fan comes on and cools down just after 1/2 way and starts all over again. Is there a way to keep the temps a little lower and more steady instead of jumping all over the place..

 

Was it this way before you did the work on it? Did you use the correct long thermostat? What temp thermostat did you install?

You can have your fans reprogrammed or get a fan switch from JET or SLP that will lower the fan ON temp.

 

it has been that way since i bought it(used)...I used all factory parts to replace things with..What do you think about a sensor that is giving a false reading? the car does have 85,000 miles on it. Do you know what starts going out at this milage and what I should prepare for? thanks...

 

It is possible that the sensor in the head is causing your gauge to read incorrectly, but it also could be right. There is some info on my Tech Page for testing the temp sensor and wiring. If you think it is suspect, it would not hurt to replace it.

As far as anything else, any sensor or part will go when it is at it's appointed time. There is no real way to predict, since most of them either work or they don't. O2s could be getting a little tired and surely the optispark was once in better shape, but I would not replace the opti until it gave you symptoms. Plugs and plug wires should be on the list of things to definitely do, if they are the originals.