ocaz

2007 civic si sedan


after jump starting my moms car, the condenser and cooling fans only come on when I turn on the air inside the car.

I only noticed because I left it idling and for the first time ever I saw it get hot!

I am talking 3/4 of the way up at 5pm 72 degress out in the shade.

Its full of coolant.

Would love any suggestions here, I know it has to do with the jump but idk what to replace.

Poopies

iTrader: (4)

Could be a thermostat thing, which would be an easy fix. No codes?

ocaz

no codes. I will try and see if the fans come on while it idles again tomorrow maybe it was a one time thing but I doubt it. I am just lucky they come on when I turn the air on. NO cel.

ezone

Of course, that's how I have made my living for the last few decades.
It's damn tough to do it over the internet though.

So how about if I give you some handy info to work with? Maybe it will help you to figure out what happened.


Scatterbrained thinking ahead:
You checked in the radiator cap, not just the reservoir?


So they both are able to run, so that might rule out 2 of 3 relays and probably the fuses necessary to run the fans -- Fuses 1,2,6,7,11,15 in the engine compartment, and #36 in the dash box.
The 3rd relay is used to switch between low speed and high speed.

The AC system runs the fans on low speed until system pressure reaches 221PSI, then it kicks the fans on high.
The coolant temp control only runs the fans on high speed. ..... So if you are missing high speed operation, this might explain your overheat?

Fans are not turned on by a separate coolant temp switch anymore, the ECM decides based on coolant temperature sensors.

First I grab my HDS scanner.
I want to know what the computer is seeing and doing.
Is the engine hot?
Is the radiator hot?
How hot?
Manually verify the temps that I see on the datalist.
Is there any other data amiss that might give a clue?

Can I command the fans on with the scanner?

The ECM should run the cooling fans on high speed when the radiator temp reaches somewhere around 206*F.
This temp is seen in PID: ECT2, the sensor is in the bottom tank of the radiator.
(ECT1 is coolant temp in the engine and the ECM does not use this to operate the fans.)

Next I want to know if the radiator is actually getting hot, and how far the heat goes.
Does the entire radiator get hot, or just the top tank?
And how hot is it when the gauge shows too high? 180? 200? 212? 220? Cold?

speedy25

With the large amount of crazy electronics in todays cars getting a surge of voltage can damage almost anything.

Unfortunately, following ezones logic is the best you can do to find a real solution.

I had a wacky problem where the fans were on ALL the time and that was finally traced to a bad climate control.

Fixing cars isnt always easy. Good luck with yours. Dont forget to report back what you found.

-SP