Jonathanc5Z0619

Hey guys, my Z06 seems to be running hot and is scaring me.
my High speed fans kick on at 235 (coolant temp) and it seems I have no low speed fans coming on.
on the highway im running around 180 but when I stop it always gets up to 235, bounces back down to about 226 then back up to 235-237 (repeating).

any Ideas?
Note: I replaced the thermostat but nothing changed

493lszosix

Sounds normal unless you’ve had the fans programmed to come on at a lower temp

Jonathanc5Z0619

is there no low speed fan? I read that a low speed fan should kick on around 219 but I was not sure. Also my oil temp gets to the mid 230s everyday because of this.
to be honest I just got my Z06 within the last few months and I never noticed this until a week or so ago.

Vetteman Jack

Moved to C5 Tech.

feeder82

The low speed cooling fan is commanded on when the coolant temperature reaches 108°C (226°F). It is turned off if the coolant temperature lowers to 104°C (219°F). The high speed cooling fan is commanded on when the coolant temperature reaches 113°C (235°F). It is turned off if the coolant temperature lowers to 108°C (226°F). When the A/C is on and the coolant temperature reaches 85°C (185°F), the low speed cooling fan will be turned on at vehicle speeds less than 56 kPh (35 mph).

gimp

You have two issues.

The first is your fans - you think. It is entirely possible. The low-speed fan setting is pretty quiet. It should turn on at 219F if the settings for it are factory original. It can be turned on at lower temperatures if your AC is on. The high-speed setting turns on at 235F, off at 226F, which is exactly what you're seeing.

Have you verified that the low speed is not turning on at (eg) 220F? Turn the car on, drive it a bit to get to maybe 150F, pull into your driveway, pop the hood, let it idle till it gets warm, and observe the fans directly. You may just not be seeing it.

The second is that your temperatures reach 235F at idle. This, along with the fact that high-speed fans bringing temps back down to 226F, is almost always a sign of a dirty radiator. What you need to do is to get the car up into the air, then use compressed air to blow the radiator fins out, from the back to the front. A handful of dirt can raise your coolant temps by 20F easily. A stock C5 should not get to such high temperatures at idle unless maybe you're in Death Valley or something.

Jonathanc5Z0619

Hey there thank you for the information! I checked the fan and they do NOT come on at 226 only 235. is this a relay or possibly something else? Tomorrow I will blow out the radiator from back to front like you said.

GCG

Just to double-check: when high speed kicks in, are both fans running?

There are 2 circuits:

1. Low Speed (½ the speed) - fans configured in a Series Circuit where ½ the voltage is applied to each fan.
2. High Speed (full speed) - fans configured in a Parallel Circuit with full voltage to each fan.

In a Series Circuit, any open point in the current path should prevent both fans from turning ON, as you are reporting, but in a Parallel Circuit it's possible to have none, both or either one. We need to know that to be able to troubleshoot this.

tiojames

Had somewhat of the same problem, turned out to be the circuit breaker in the fuse box.

Ramets

I'm not very technical, but when I had the heating problem I checked the radiator for debris. First I crawled under and reached up with my hand to pull any crap out from the front of the radiator. Geez, you would have thought I vacuumed up my lawn by all the pine needles and such I got out. After that I decided to blow it out too. It solved my heating problem. Now I check it about once a month. The damn car is like a vacuum cleaner going down the road.