2005 TOYOTA COROLLA COOLING FAN WONT COME ON BY ITSELF BUT…

Ok , let me go ahead and check the diagram and see what I can come up with.

Does the fan run when the a/c is turned on?

Ok, be right back.

Yes, irt does.

Ok, I'll be back shortly, yes the a/c not working can be related.

Pull the #1 fan relay out, turn the key on, there should be voltage to terminal #1 and #5 in the relay socket, just measure each for voltage there are two terminals that are supposed to have 12 volts, let me know how that goes.

hello, if you need more time to do this please just reply when you get around to doing the voltage check, tomorrow is ok.

Ok sounds good.

Ok there is voltage to 2 of them which is good.

Are you sure the engine gets hot enough to turn the fan on? When the a/c is off the fan is still supposed to turn on when the engine gets hot so the a/c not working has actually nothing to do with it, the only time the a/c is involved is when it's on and the compressor is running this will cause the fan to run at high speed, with the a/c off the fan is still supposed to turn on when the engine is hot it just runs at a lower speed. It's important to be sure the engine gets to operating temperature.

Ok, we're going to have to do another little test, there is a two terminal pressure switch on one of the a/c pressure lines, should be on the high pressure side next to the service port with the cap on it, take the connector off and put a jumper between the two teminals, with the key on the fan should then run at high speed.

The engine control computer turns the fan on and controls the fan speed based on the temperature input and if the a/c is on or not it does this by grounding the #2 terminal of the #1 relay, do you want a copy of the diagram, one thing you can do is to ground the #2 terminal of the relay, that should make the fan run because the computer is bypassed, it will take a few minutes for the diagram to get to you.

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You need to ground the #2 terminak somehow with the relay installed, with the key on the fan should run, if it does then either the relay is bad or the computer, I'm sending you a diagram of the relay terminals in a minute.

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Sorry I didn't get any pictures you sent

Then if the relay is good it should close and make the fan run. Jump across terminals 5 and 3.

Fan relay #1 as marked in the fuse /relay diagram I sent. NOT relay#2 which has 5 terminals relay 1 has 4.

No, pull the relay and jump the two terminals in the socket.

I'll be right back

In the fuse box picture I send locate the 30A RDI fuse, check voltage to ot and make sure the fuse is not blown.

Yes it has a clear top and is bigger be sure it's the right one as marked in the diagram the third large fuse down.

Pu the #1 relay back in, remove the #2 relay and ground the #3 terminal.

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This is the relay diagram

You should see the diagram in my reply by just clicking on it,

Sorry, nothing sdeems to go right so I'll have to opt out and besides I have an appointment tonight, I'm sure someone else mav be able to help after I log off.