With the car idling in park with a/c on should both fans be on the passenger side fan was the only one on. With the ac off when the car hit 226 degrees only the drivers side came on. do i have a problem.

 

I have always thought my passenger side fan was the only one that ran, after reading this and the links supplied, just went out with a a flashlight to see.

Ok, on my car, with A/C on, it seems only the passenger fan is coming on, and it cycles between low and high.

For years I have noticed the inside blower motor(blower on highest speed) would stumble for a bit as if it were losing power, and I believe this is because the high speed fan is hogging the juice, then the blower speed seems to ramp back up.

Now, with the car warming up, with A/C on full blower and set to 60 (low as it will go) it seems the passenger side fan runs all the time, I thought it was freewheeling after being turned off, but kept waiting.

Turned off A/C and it did come to a stop.

So, I'm going to go back out and start with the fuses, then relays, and will report back.

Question, if one fan is out (fuse, relay, burned up wire bad fan motor,etc.) would this make the ECM go into a default to run the passenger fan (or vice versa) continuously, and cause it to go from low to hi and back, even at temps below 185(this with the A/C on), mine is doing this as I just witnessed?

 

All 3 fuses are good, see no holes in the any of the 3 relays, the one relay that is smaller and black, the shell or cover came off when I tried to pull it off, snapped it back on and pulled again with pliers, came out as one unit.

Then I pulled the cover off, and all looks ok inside, no burns, although I know I can't rule it out.

The others, I think the covers may be hard to get off.

I checked for continuity between the 85 and 86 terminals to check for a open coil, both have continuity.

I should pull the black one and check it this way also.

 

Good information 8vettes7, I am trying to find my small jumper wires with alligator clips to go from the battery positive to terminal 85 or 86, and battery negative to either 85 or 86.

I would hope these relays could not be damaged by reversed polarity?

I could also try using the jumper wires to jump between 30 and 87 in the female slots where the relay plugs in to see if the driver fan kicks on.

From the diagram, it looks like I could just turn the ignition to "on" and if the fan is good, it should start spinning?

 

I see you made a update edit to your post, I will get out there and check it out, and report back.

Being lazy, before getting the car on the ramps, I'm going to try to spin the driver's side fan to see if it's free.

 

Ok, it's a bad fan motor, not locked up, just no go with juice!

I see I can get one for 44 bucks at Autozone.

Continental/Radiator Fan Motor
For your 1999 Chevrolet Corvette 5.7L SFI 8cyl
Price: $43.99



Part Number: PM537
Alternate Part Number: VT39379

Think that is a good brand, Continental?

 

I was amazed at the grease I got on my hands from the fan, I'm gonna guess that is from other's car's that drive in front of you, their oil mist being sucked up on the fan, over the years?

 

Thank you for your help!