Fan not coming on - followed steps in a thread here - need help.

[Zooler]

My radiator fan isn't coming on.

This is compounded by the fact that the coolant temp display isn't working. Well, it worked temporarily this morning (after I banged on the plastic display cover), and showed temp at the top of the white while idling. I shut it off.

So, I read up here on the fan. Petros posted a troubleshooting guide in one of the threads. (Thanks for that!)

1. If I disconnect the wire going to the radiator sensor, the fan DOES come on.

2. I just replaced the sensor with a used part that a friend said should work (off another Tercel). It hasn't fixed the problem. I am scared to idle it too long as I don't know the engine temp.

3. I also replaced the coolant temp sensor (has a small clip on it), it's on the front of the block. I assume this is the one going to the dash. No display still.

So, if unplugging the wire causes the fan to come on, is it possible for the problem to be anything other than the radiator sensor?

Thanks

[Zooler]

Update:

I changed the radiator sensor a second time. And now it is coming on (although infrequently). Hopefully it's operating normally. It is rather stressful not having a functioning display in the dash.

I also changed out the two sensors on the front of the engine. One connects to a wire via a metal clip (I believe this to be the sending unit for the dash?).

What is the one to the left of it with the green connector? (Right near the thermostat.)

[Petros]

the one on the front of the head is for the temp gauge on the dash, the one on the head coolant outlet (green connector) goes to the relay box behind the glove box to control emissions system (they call it an ECM or some such thing as if it is a computer like on the EFI cars, but it is just a simple "if/than" relay box).

You can go get an inexpensive coolant temp gauge at an auto parts store, or from rockauto.com, and install it to keep and eye on the temp until you are satified that everything is working normally. they do not cost much (usually less than $20), and it is a good dianostic tool, and you can use it to verify the built in temp gauge once you get it working again.

good luck.

[gnarnold]

Get it fixed yet

[gnarnold]

You know I know this has nothing to do with the cooling system but recently I had a problem with my lights flickering and gauges not working of and on it turns out that the voltage regulator was going bad and was the reason for the weird electrical behavior
.I mean I drove for years with my brights on because low beams were as bright as cozy dinner for two .now I can't believe how amazingly great everything works.just so you know .also I had a problem with my fan the switch at the bottom of the rad was the culprit I like to put a little more (stuff called dia grease or do ..electrical grease ) .inside the male plug tube .I think i went a bit too heavy and had to use a thinner coat of rtv sealant around the side of t stat to kinda hold in plce during installion .and don't let anything drink the coolant. Not good.

[Petros]

not ususally a problem, but with older cars often you are dealing with more than one problem (and sometimes more than 2!) at the same time so it is difficult to narrow it down by standard means. Or you find one of the problems and fix it, and it helps but does not fully fixed it, so you feel you wasted because it is still not running right. All you can do is fix each issue as you find it, and than move on to the next one until it runs good again.

[gnarnold]

I think I can see a pin hole size light at the end of the tunnel .kinda like the work on the golden gate bridge .start on one side by the time it's done it's time to do it again .a year I think it takes

Oh and also don't get a rad cap at the 99 cent store .spend the extra 5-7 bucks and get one that will last a little longer

[Petros]

don't get a rad cap at the 99 cent store .spend the extra 5-7 bucks and get one that will last a little longer

I recommend not buying any parts made by communists in China, not worth the risk, nor the effort no matter what the savings.