Hey guys, so for a 94 Auto Coupe... How many fans for cooling does the car have? I can see one on the drivers side of the radiator, but could swear that I hard another one, possible in front of the radiator, haven't even looked.. I thought that when you turn on the A/C, a second fan came on automatically with the A/C to provide air to the A/C condenser and for additional cooling for the radiator? Just recently my car hit 240 degrees and I just replaced the thermostat, which seems to have fixed things, (I think), but if I have a fan not functioning, I need to address that A.S.A.P.
Who knows and can shed some light on this for me? I think I see two fan relays near the drivers side headlight?? HELP!! Right now I can only hear one fan, which is on when I start the car no matter how hot or cold the engine is...
Thanks,
Kevin.

 

For the 94 car it does have 2 fans.

The driver's side comes on with the A/C, or at 219* (with no A/C).
The fan on the passenger side or secondary fan come on at 239*. You have to get that hot and in regard to the temperature displayed on the digital indication on the speedometer.
Your car sounds normal.

When it's 90*+ and sitting in traffic the temperature will skyrocket (crazy).You can install a simple switch which can turn on the secondary fan when you want to, as I did 14 years ago.

 

 

The driver's side fan should not come on (normally) with no A/C and cold. Could be stuck relay, someone added a ground wire, or short on that wire to energize relay. Possible bad PCM but probably not but all of this can be tested and checked.

Yes, adding a switch is as you described. But I need to get the detailed information together and get time to write it up….later.

 

 

This all looks A1 perfect. Look likes you don’t need much help, you way out front.

Yes the PCM can be programmed to change the turn on temperature point.
Having said that, this is my personal view and is my opinion and non-technical.

I'm do not want to flash the PCM just to change the turn on point and possibly cause a software load problem. I want manual control as driving conditions change with ambient temperature. If it is 95 on the control head display and you hit 220, I don’t know if it will come down or just stay up there where I don’t want to be. I turn the secondary fan on somewhere in the teens or whenever I feel I need it. I do not want to go to 220 if I can help it. I can think better than the PCM can at least for this situation. Some may not agree, I don’t care what the engineer specs say and I know I'm within spec, I'm not cooking my plastics and electronics at 230 or 240.

 

If you'd rather have things automatic, and not reprogram the PCM, you can also use a thermal switch to turn on the secondary fan (the passenger side) by providing another ground path for the relay for that fan.

That's how it worked in the earlier C4 Corvettes. They had a switch in one of the heads (usually driver's side between the #1 and #3 spark plugs) which activated the secondary fan (through a relay).

The early C4 Corvettes (through 1989 IIRC) used a 238°F on, 220°F off switch in that location. The Camaros from those years (and some other GM products) used a 215°F on, 200°F off switch. The part number for the lower temp switch is GM 14043275, AC Delco D1855B. Install one of those in either head (between #1 and #3 on the driver's side, between #6 and #8 on the passenger side) and use that as a ground to activate the secondary fan.

If 215°F is too hot for you, there are some aftermarket alternatives that activate at 200°F and turn off at 185°F.

And please, for the love of God, clean out in front of your AC Condenser and between the AC Condenser and the radiator. I'll bet good money you've got lots of leaf debris and possibly some rodents living in those spaces and blocking air flow through your radiator.

 

Yes, you can get a temperature sensor that will kick the secondary fan on at about 210. If you go to AZ, they have them in stock (mine did) and I swapped it in about 10 minutes. The sending unit is located between spark plug 1 and 3. Put a socket on it and spin it off and quickly swap sending units as you will lose some fluid. Mine worked perfectly on my L98 with the fans coming at 208.

 

YES! Here is what I found when I looked at my 89

 

WOW, great info on the automatic switching... I may look into that for sure. When I pulled the air filter box and air intake to change the thermostat, I did clean out a handful of pine needles in front of the air intake, which may have been causing a small issue, but not really sure if that area matters for cooling. Today I took the car to church, about 20 miles each direction and the car ran great. It's only about 85 degrees today, but on the way there the car hit 190 and stayed there for about 5 miles before creeping up to 198, then it went back and forth between 193 and 200 and the same on the ride home. This is the first time I actually saw the temperature correct itself in a negative way by going back down, before it always just creeped up and up and up but never seemed to go back down. I will take a look at the space between the condenser and radiator when I have it up on the rack next week to change the engine mounts. When I bought the car it had been sitting outside for a couple of years and had spiders living in the car. When vacuuming the car out for the first time after getting it, I actually sucked up a daddy long legs trying to escape. I have eliminated all of the cob webs now and haven't seen anything new, so I think I have her bug free now. It's a little frustrating being a perfectionist, also trying to compare this car now 24 years later to the same car I had back in 1994 brand new. I know what this car can be, so at least I have first hand knowledge as to where it needs to go to become virtually new once again. I have pretty much eliminated all rattles and squeaks and have replaced most worn components. Other than a few more minor issues like needing new carpet for the cargo floor area and new sun visors, the only thing that won't be perfect is the paint, but it is an 8 out of 10 and after a clay job, polish and wax, the car should be a 9 out of 10 condition wise. Runs like a new car now after going through the entire motor, my only regret is forgetting to install new engine mounts, and obviously the thermostat when I had the engine out last month... The support on this forum is the best... This is my 5th Vette and in 1987 my first brand new car at the age of 23 was a Corvette, I will never forget the feeling I had driving her home for the first time, it was exhilarating. of the 4 previous Corvettes That I owned, a 85, 87, 94 and 2005 C6, the 94 is actually my all time favorite, which is why I bought this one. Just a great car... Love it.

Thanks..

 

This advice applies to 1989 and earlier L98 C4 Corvettes. The lower temp switch is for Camaros of that era.

In 1990 and later, the secondary fan was also controlled by the PCM. It is still possible to wire up the earlier coolant temp switch directly to the secondary relay and use the lower temperature switch (see my earlier post for the AC Delco and GM Part #), but some additional wiring is needed to do that to a 1990 or later C4.

 

I'm sure this work also.

But don’t forget the temperature in the head is different from the temperature in the sensor in the water pump displayed as a digital temperature on the speedometer. I can't remember what temperature is higher (as I read it somewhere). But if the head temperature is higher I guess the fan would run a lot. Just something to consider.

 

After a bit of research in the GM Parts catalog, I'm going to revise my earlier statements. It does look like the coolant temp switch to control the secondary fan was on all L98 engines through 1991, not only on the 1989 and earlier models. So changing the switch for one of the lower temperature options should be all that is required on any L98 engine C4 Corvette. Again, the 215 on/200 off switch is GM Part # 14043275, AC-Delco D1855B.