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I have a 1996 corvette and Since summer started I’ve noticed that my coolant temps rise really quickly when idle but drop when I start to drive. Driver side fan does not come on even when coonat is above 228. Which parts can be causing my fan to not come on and coolant temps to fluctuate?
Last edited by Migizem12; Aug 5, 2018 at 04:18 AM.
This is a good quick test. When idling and AC on, both fans should come on and it should be noticeable even with the hood down. You'll rule out the fans and then need to move to to the debris test.
You'll rule out the fans and then need to move to to the debris test.
I agree--You will end up here anyway. Fans or not, the "inbetween" area from the radiator adn the AC condenser WILL fill with road debris after a few years clogging air flow. You will need to look in between the two and/or remove the shroud to clean out the accumulated leaves, bags and general crap. Here is what I found a few years ago after my (then new to me) 89 damn near over heated at idle. I clean out he debris and never had a problem since.
I have a 1996 corvette and Since summer started I’ve noticed that my coolant temps rise really quickly when idle but drop when I start to drive. Driver side fan does not come on even when coonat is above 228. Which parts can be causing my fan to not come on and coolant temps to fluctuate?
The fans aren't designed to turn on until a 'higher temp"....~230˚ on cars up until '95, and I believe ~212˚ on the '96 car.
When the AC is on, both fans should be running at speed below 25 mph...and those fans should be able to drive the temps down below 200˚.
The '96 has three fan relays that control both fans' speeds at the same time. I don't see any spec other than that both fans come on at 212˚ on "low", and ramp up at some, unspecified speed, according to my source. Anyway, relay #1 energizes both fans on low, then Relay 2&3 come on simultaneously to put both fans on "high". IDK at what temp that occurs. I'd guess in the mid 220's.
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Last edited by Tom400CFI; Aug 5, 2018 at 01:36 PM.
Good catch on the both on low, both on high, Tom. I always forget which year this came in, so I look for three relays for the "low high" operation. 2 relays, like on 90-91 are one then both fans, but at full speed.
Thanks! I almost posted a bunch of wrong information (earlier LT1) but then remembered..."Wait a second...'96 is different". Good diagnosis of the OP's issue off the schematic!
So to add some information and simplify some of this here's how things work for normal operation
The fans come on with the A/C in low speed, or at 228* .
The fans come on at 239* in high speed.
By using the configuration of the relays this is what happens. In low speed the fans are put in series thus dividing the voltage in half for each fan.In high speed the fans are put in parallel across 12 volts having full voltage for each fan.
If one fan is not turning the winding is probably not open cause in a series circuit the other fan would not run either. So I'm thinking the left side fan may be frozen. I would give it a push or a turn to see if it will move and wants to go.
Not sure what a bad relay might do as there might be a list of effects
Coolant temp fluctuating
