shadow man

I have a 96 LT4 running too hot. Can anyone tell me how to lower the temp that the engine fans go on?? Could be in the computer or it could be a valve in the system or something else. Thanks

FASTAZU

Has to be programed in. mine are set to on 210 off 205 works great. You have 2 speed fans on the 96 so just find someone who will reprogram the on and off temp.

johno504

reprogram to : 95 centigrade fan ON ,90 C OFF. END OF PROBLEMS AND STORY . I did mine last year . zero issues since.

billschroeder5842

What does this mean exactly? What are you seeing? These cars tend to run "hot"

barchetta1

If you anywhere near Charlotte nc stop in and I will do it for no cost.

shadow man

When I am in traffic,or going up hills the heat gauge needle moves up quickly and too high. Sometimes it goes as far the the right as it can. I can feel the excessive heat outside of the car and under the hood if I raise it.
Some cooling takes place if I turn the A/C off, put the heater up to 90 with the heater fan turned up, but sometimes that does not help
I know they run hot but this one on hills and with the air on just runs too hot
I am replacing the thermostat and rad cap today and will get it to a tech to see if the fans are both working and if so to lower the temp that the fans go on.
Hope this explains what we are talking about. If your car doesn t run too hot you probably have no problem
A new radiator will be my last resort

shadow man

Thank you. You are what makes car folks so special. Unfortunately the car is in East Tenn and too far to drive it too you with this problem.

Mr. Peabody

1) a very easy way to check your fans is to just open the hood, start the car, turn on the AC, both fans should come on at the high speed by default.

2) Do not use the analog gauges be sure to get your temps from the digital readouts.

3) Read this...... lots of Excellent Info here: https://www.corvetteforum.com/forums...peratures.html

3D-Aircrew

<br />Yes determine when the fans come on but also check your radiator for debris ... bugs, grass, leaves, plastic bags all get sucked up by these vacuum cleaners.<br /><br />Also you might want to get one of these. It has a laser beam that you point to different parts of your engine to determine temps.<br />


Craftsman 50466 High temperature infrared thermometer

Purple92

As the other posters have indicated on the LT1/LT4 cars - the Fan 1 and Fan 2 "ON" temps are programmed into the PCM. Typically the LT1/LT4 cars go to full FAN ON around 228 - 230. Even in traffic your car should not go much above 230. On the highway - you should be no higher than the mid 190's. (Those numbers are based on the digital display - the analog gage is normally pretty good - but some have reported it being off considerably).

In order to change the fan ON / Off temps - you have to reprogram the PCM. That's not too hard to do on the 1996 and some 1995's which have a real (early) OBDII system - that allows reprogramming through the OBDII connector. On the earlier cars - you have to pull the PCM, open it up - remove the EPROM, read the file, erase the EPROM by exposing it to strong UV), then edit the file (to change the Fan On temps and Fan Off temps - and maybe a few other things while you're there) and then re-write the file to the EPROM. Then reinstall the EPROM in the PCM Module, and reinstall the module in the car. If you have all the equipment to do that - it's typically a half hour or so worth of work, but not very many people have the equipment....

If your car is running hotter than the numbers I posted - I would suggest using the IR meter (gun) that other posters have described to verify that the numbers you're seeing on the digital display are correct. If they are - I would suggest doing the following:

1) A full cooling system flush - which involves draining the radiator AND pulling the two block drains (knock sensors) and getting all the old coolant out and nice fresh coolant into the system. Many people are pretty amazed to see what comes out of those block drains - particularly on cars which have not seen "stellar" maintenance throughout their life.

2) If the cooling system flush doesn't solve the problem - the next thing to do is to pull the radiator and clean the crud out that accumulates between the A/C condenser and the radiator. This is not a real fun job - (there are six small 7mm screws that are not your friend...) but many C4 owners have been rather surprised to see how much crud accumulates in there.

I would expect that the cooling system flush and the rad "cleaning" will resolve 90+% of the running hot issues people encounter. The OEM radiator is sufficient for a stock or mildly modified motor. Get into more serious mods and you may need to upgrade to a better rad - but that should not be necessary with a stock or near stock motor.

GOOD LUCK !!!

barchetta1

Radiator cap is critical. Pick up a cap tester.. very important tool.
Pickup some commercial air conditioner coil cleaner. I use "coil king" and it is very very strong. Mix it with water and spray on, wait 5 minutes and carefully rinse it all off. My radiator and condenser coil shine now.

Also, on the passenger side of the car shine a flashlight inbetween the coil and radiator.. most people find a substantial amount of debri there. Some more some less.. I found a substanial amount and carefull cleaner it out with a nice vacum cleaner attachment that was very thin and long.. it avoided a big job removing the coil or radiator.

Lastly, throw out your "performance filter" if you have one. they are junk.

TerryOlson

Corvette Central sells fan temp sensor switches which turn the fan on and off at lower temperatures than the stock one does. I was seeing 230-240 regularly with the stock switch and stock 195 degree thermostat. These cars are designed for it etc. That said, my feeling was that this high temp was causing the fuel to boil when the car is parked when it is very hot out and that this was causing the dreaded hot-start problem that isn't all that uncommon. I installed the new fan switch and a 180 degree thermostat and I'm now seeing 180s and once in a while when idling in hot weather with the AC on 190 degrees. Most importantly, I haven't had the hot-start problem since. Another route to the same destination.

johno504

the OP has a 96, NO need for all that bs,.just reprogram the ECM and go straight to the destination. I have a fan over ride switch, etc. on my car still , just have not gotten around to removing it. have the 180 , 2 new fan motors, new radiator and electric 43 gmp water pump. (2) fans turn on set at 95 C, have NEVER seen a temp over 205, and that's in the DEEP South. all of that being said, it did cost some $. the switches should work ok, just not the optimal solution. HOT start problem ? had that on my Pantera, never on the last 5 Corvettes.

drcook

If you are experiencing that much temperature rise while the car is moving, you need to look for something in the cooling system. Such as being dirty (as said above), etc. My '96 will run up to the programmed limits (yes even with the DeWitts radiator) because of where the limits are set, but the fans will come on. It will even run up hot when driving real slow or sitting when the outside temps are high, but when the car is moving with adequate airflow, you should not have temps going up that high.