Can someone tell me what the parameters are for the operations of the coolant fans?

I know they are set to turn on at 226 degrees but it seems that they are only coming on in "low". I've been able to manually get them to come on in "high" but left to the PCM, they don't seem to come on "high".

TIA

 

Low speed = 226degF
High speed = 235degF

 

Thanks Fred. I asssumed somewhere around there. I can't test it right now because I boil over before it gets to 235

I'm chasing it down and should have it resolved soon though.

 

You might want to change the radiator cap if it boils over before getting to 235.

 

sry to come in on the thread like this but im having the same problem. if you would let me know what it is so i can fix it. its been bugging me for weeks, and after changing out everything in the cooling system except for the radiator and fans, i still cannot figure it out. i was thinking of running a power switch to manually operate them, but not sure about it. i want the fans to come on at lower temps, and run on high while on, it makes no sense to me for them to run on low. thanks mike
mikd24@yahoo.com

 

We're on the same page. It is only a couple years old but I'm replacing it today to see if it helps.

I didn't go into a lot of detail because it is a complex set of coincidences including intermittent failure of one or more wires or connector connection at the PCM, a broken coolant overflow tank and a few other things. But, thanks for the input.

 

Having the same problems also, but my fans arent coming on at all mine has gone from bad to cant get any worse.(blown head gaskets, melted waterpump, radiator) I have had a broken coolant overflow tank for a long time, but I didnt think something simple as that could affect anything.

 

A broken coolant overflow tank isn't causing all your problems. I mention it as just another problem I'm dealing with. But, if it has a leak, you will loose coolant whether the coolant is "boiling" or not. Coolant is in constant flux betweeen the radiator and the overfolw tank depending on whether the coolant is hot or cold. So a hole or leak will just cause the coolant to leak out when it gets to the level of the leak. When it truely is "boiling over" the coolant overflow tank is designed to overflow at the cap. That's why there's vents in it. Mine was broken where the battery tray is glued to the tank so every time my coolant would flow into the tank and get to that level, it would just pour out.

If your fans aren't coming on at all I certainly wouldn't drive the car until I got it fixed. Are they getting power? Will they come on when you turn the A/C on? If so then you at least know they are getting power and physically work and at least you could connect a direct switch to turn them on manually. Lot's of racers do that so they can leave the fans on in the pits or just to turn them on early or to always run them on high.

The list of reasons yours aren't coming on at all (again, assuming they work and have power) could incude a lot of things including the relays (3 of them), the wiring from fans to relay box to PCM, the connectors between the wiring harness and the PCM, the PCM itself, etc. If you have a Helms or other service manual, it should give you a list of items to trouble shoot the cause.

I hate these kinds of problems ... good luck!