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97 lesabre cooling fans wont come on


buicksuck123
02-16-2016, 09:57 PM
My 97 lesabres cooling fans wont come on. the car gets pretty hot when driving around town. I saw on another form that they should come on when the Air Conditioning is on but mine does not. I got the fan to come on when connecting it directly to the battery so i know the fan is good. I replaced the high speed relay with the horn relay and still nothing.

Im not apposed to putting a switch in the cabin but im not sure the best way to go about doing that. Any help is appreciated.

brcidd
02-17-2016, 09:48 AM
"Pretty Hot" Hmmmm-- to some that is boiling over- spewing coolant on the ground- to others that is needle on gauge just a hair above half (or normal).

I get this question all the time- "my fan(s) don't work! How do you know? The fan(s) are designed to come on when needed by the PCM. And there are numerous conditions that need to be met- it is actually a good thing- unlike the mechanical fans that consume horsepower when not needed. The fans need to be off when driving so as not to consume electric power and save energy and hp.

So here are some conditions- Engine temperature as seen by PCM (not dash) as 227 degf or so for fan1 (or low speed)- and about 237 degf for fan2 (or high speed)- unless you have a Tech II to watch engine temp and fan status, you cannot be certain if these conditions are being met.

I have tried with Tech II attached and had to let car idle for 45 minutes with a blanket over the hood and grille- to finally get engine temp up high enough to request fan1 on when it is 70 degf out!

Just because the temp on gauge on dash "is a little higher than normal" is no big deal-- In the red zone IS a big deal....

A/C operation will command the fan on constantly- only on particular car applications- yours being a GM "H" car means it will wait for a/c head pressure to reach 175 psi before fan activation-- so unless you are testing at 80 degf ambient with a/c on, chances are real good that the a/c pressure is not high enough (a/c evap load is low) and your variable stroke compressor is not generating enough head pressure by design (175 psi) to turn the fans on--because the ambient temp is too low.

Bottom line- I get more complaints where there is not a problem (like I suspect you are experiencing) then when there is.

polarzak
02-17-2016, 07:43 PM
Excellent reply, brcidd, very comprehensive.
Short story...my neighbour was complaining about his fans not working, and was monkeying around with them with the engine running. Nearly lost fingers when they suddenly started up. There even was a sticker saying fans can start any time. :headshake

buicksuck123
02-17-2016, 07:43 PM
i agree with that after doing some test with a paperclip in the coolant temp switch connection. I also did get both fans to come on when the dash got just over 200. So you are right i was being paranoid.

DeltaP
02-18-2016, 08:53 AM
I don't think the horn relay is compatible with the high speed fan relay.

buicksuck123
02-19-2016, 07:33 AM
delta p the horn relay had the same part number. That means it should be the same correct?

DeltaP
02-19-2016, 09:21 AM
That's rare. OK I guess.

brcidd
02-19-2016, 09:46 AM
A lot of car companies do that with relays- even though the horn uses only four terminals, they use the 5 terminal relay that is needed in the cooling fan circuit- just to maintain commonality- finally a nice feature for the owner presented by the manufacturer. Cuts down on assembly mistakes as well.

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