Strange Fan Behavior

[NC2Stay]

I went out for a ride with my wife on this gorgeous spring day, and stopped for a few minutes (with the engine on) at a local scenic spot.

The temp zoomed up. I don't remember what the digital gauge said, cause when I saw the analog gauge shoot up, I hit the A/C switch and got going.

Luckily I remembered that somebody here had said that turning on the A/C turns on the radiator fan.

So, I ran with the A/C on for a while, and all cooled down nicely (about 195-200). I then shut off the A/C, but I still heard the fan run and the temps stayed fine.

So, what can we deduce so far: a) the fans work. b) the fan relay works - but is it the same relay used for the A/C and for high temp? c) I think the temp sensors are working OK, as evidenced by the digital and analog metering.

But why did the fan stay on after I turned the A/C off.

Anyhow, could somebody give me the short-to-medium sized course on what is going on here? What relays? Where? What sensors?

Thanks, Bob

 

[NC2Stay]

Bump. Somebody has to know this:

a) What temp does the first fan go on/off at? Is this the "primary" fan or the "secondary" fan?

b) what temp does the other fan go on/off at?

Which fan(s)/when turn on when the A/C is on? (regular A/C, not climate control).

Thanks, Bob

 

[Rabbit]

If memory serves...Both fans on "Low" at 228*. Fans, in concert, on "hi" at 238*


Both on "hi" when A/C "on".

 

[WradDad]

I tested this last night. In the garage, I let the car warm up to about 220, then turned on the A/C. Both fans came on high speed. They stayed on high speed until the temp came down to around 213, when both fans went to low speed. I turned off the A/C, and both fans stayed on low speed for about 45 seconds, then shut off.

I then let the temp go back up, without the A/C on, to 228, when both fans came on low speed. Sitting in the garage with the hood open, low speed was enough to pull the temp back down to 200, and I couldn't get the fans to come on high speed without the A/C on. I do know however, that sitting in traffic on a hot day here in So Cal, both fans will go to high speed operation without the A/C on. Maybe they go on low speed first, then if that's not enough to bring the temp down, they go to high speed?

Barry

 

[NC2Stay]

Thank you for going out and checking it.

Well, I think I have a problem, then. I didn't note exactly what happened, but I am sure it was well above 228 and still no fans. But since the fans come on for the A/C, that says the fan controls themselves are OK

So, if the ECM knows that the temp is high, and is able to turn on the fans when the A/C is on, why can't/doesn't it turn the fans on for high temp?

I am going to go out and try it again tomorrow.

Bob

 

[NC2Stay]

All is cool - pun intended. I went for an hour's drive today (about 75 degrees) and it never went over 200 except when I did some slow stop-and-go, and then never higher than 213.

When I got home, I just ler her run in the driveway, and the temp slowly crept up. It actually took quite a while to get to 228, but when it did, the fans did come on low. The temp hit 229, and then quickly settled back to the 2-teens.

I think the issue may have been the analog gauge. It seems to be reading high - I have seen other posts saying to basically ignore it, and so I will!

Thanks for the help, Bob