Why won’t my Corvette’s cooling fans turn on?
Today’s Corvette technical question comes from Jim, who owns a 1990 Corvette:
I have a 1990 Corvette convertible with 350 and 6-speed that I can only drive when the weather is cool because I cannot get the cooling fan to run. The fan motor is good (works when voltage is applied) and I have replaced all of the temperature sensors and the cooling fan relay, but still no fan operation. What else could be preventing the fan from running?
Answer: Your Corvette’s main cooling fan is controlled by the PCM. The PCM sends a ground signal to the fan relay when it sees the desired temperature to run the fan has been met. You need to check the relay and make sure you are getting your battery 12V and ignition 12V when the key is on. With the key on, jump the ground wire in the relay. If the fan turns on, you have an issue in the PCM and it may be time for a rebuild. If it does not turn on, then your problem lies in the fan circuit between the relay and the fans.
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I had the same problem with my 1984 Corvette. I replaced the sensors, switch and fan motor. The problem was the temperature sending unit.
I had the same problem with my 1986 Corvette. I found out that I had a bad wire running from the battery cable.
Perry
Nassau, Bahamas
Excellent info, especially considering I am looking at getting a Corvette for my next car.
Where exactly is the cooling fan sensor on a 1985 Corvette? Finding all kinds of similar units but they are not like the replacement we bought.
John,
The relay is mounted on the inner fender well on the drivers side, right in front of the battery.
What are some common reasons for my 1996 Corvette not blowing warm air?
Craig,
It is very possible that your Corvette’s Hot Water Shut-off Valve has gone bad.
The dealer replaced the fan motor and they come on at 225 degrees. The dealer says thats were the fans should come on but that is way to hot for me. We live in Florida, I am going to try a 160 degree thermostat, purple ice w/water and 1 gallon of 50/50, hopefully that will help. If any corvette owners know otherwise please let me know.
Thanks
Stephen
Stephen,
The factory fans do come on at 225, this cannot be lowered by a thermostat. If you want to lower the main fan temperature on a C4 Corvette it has to be done by either a chip in the ECM or programming on 1994-1996 Corvettes. You can also wire around to a switch. On 1984-1989 Corvettes with dual fans there is a temperature switch in the cylinder head that controls the front fan. Our 1984-1991 Low Temp Fan Switch Conversion Harness will allow you to wire an extra ground wire to the main fan relay. When the switch hits its preset temperature it will ground the relay and turn the fan on early.