Coolant Fan runs all the time...

[hewhobarksatdogs]

Worked fine until yesterday. Too warm? the fan comes on, cools off, fan turns off. Now the fan is on as soon as I start the car, cold engine. Checked the f**king Haynes manual, wiring diagram for everything but the fan. Need to get this fixed so I can go to work tomorrow and not run the battery out. Any suggestions? What triggers the fan? Is it a straight thermo-switch or does the computer somehow get involved? Any good work-arounds in case I can't get this figured out right away? HWBAD

---------- Post added at 05:35 PM ---------- Previous post was at 05:27 PM ----------

Oh yeah, it's an 89 Dodge Lancer Shelby 2.2 TII

[85boostbox]

2 things control the fan. The relay and the coolant temp switch. Run codes and see if there is any codes in it.

[cordes]

So it's on when the key is forward, or all the time? If it'll turn off when you remove the key then you can at least get to work.

There is a relay for the fan. That could be stuck or the computer may not be seeing a coolant temp sensor signal for some reason. It'll throw a code 22 if the latter is the case.

[4 l-bodies]

I'll bet the relays contact points are sticking together. Remove relay. Bend the tangs to remove cover, take a ignition file and file the points squarely to remove pitting and that may fix the problem. I've had this happen about a dozen times over the years. Also check the three wire connector to make sure it isn't melted. That is another common issue.
Todd

[turbovanman²]

If its only on with the key on, 10:1 its a faulty coolant sensor or the a/c is wigging out otherwise what Todd said.

[hewhobarksatdogs]

It runs only with the key on. The coolant sensor is the one that is screwed into the thermostat housing, right? And, if it is conducting (on), i.e. sensing enough heat to conduct, the fan should run, true? Then, if the fan is running because the sensor is stuck "on", and I disconnect the plug to the sensor, the fan should stop, right? That is not happening. Fan is running, I disconnect the sensor connector, fan still runs.

---------- Post added at 06:52 PM ---------- Previous post was at 06:51 PM ----------

So where is the relay for the fan?

[85boostbox]

No when you unplug the sensor it will come one if it was functioning correctly. And I am honestly not sure which relay it is. But it will be on the left side of the engine bay on the strut tower or inner fenders. I would have to look at a manual to figure it out. Just check your codes and see what codes you have.

[cordes]

No when you unplug the sensor it will come one if it was functioning correctly. And I am honestly not sure which relay it is. But it will be on the left side of the engine bay on the strut tower or inner fenders. I would have to look at a manual to figure it out. Just check your codes and see what codes you have.

It's the one with the larger green wire coming off of it. It's the same green wire which goes to the fan.

[hewhobarksatdogs]

Wow. I have been looking at the wiring harness and trying to figure out where the relay is located. On the inside of the driver's side fender, inside the engine compartment, attached to the shock tower, are a couple of cans that look "relay-ish". One of them has a green wire going to it. Unless someone can point me to something better I am going to take that one off, open it up, and see what I can find. Thought about tracing the wire back from the fan but everything is pretty well wrapped and, as much as I like an adventure, I would prefer not to un-ravel all of that if I don't really have to.

---------- Post added at 09:50 PM ---------- Previous post was at 09:48 PM ----------

Oh, another big "duh"; how does one check / interpret the codes?

---------- Post added at 09:51 PM ---------- Previous post was at 09:50 PM ----------

And, just to know, if it became necessary for me to drive the car as is, would the fan running all the time run the battery down or can the alternator keep up with the load?

[zin]

Without a scan tool, you can check codes by doing the "key dance". IIRC, it's on-off-on-off-on, then wait for the check engine light to start flashing... all the codes are two digits, you'll get set of flashes for the first number, then a pause, then the second. The first will be a self check, indicating that the computer is OK, it will end with another code (55?) to indicate the end of the codes. The ones in between will be the "real" codes.

Take a look in the Knowledge Center for the actual codes and more in-depth info on checking/fixing codes.

You have the right relay if it's the one with the green wire going to it, BUT, if it doesn't run all the time, which you've stated it doesn't, the contacts aren't stuck, so you shouldn't have to open it up, and I wouldn't, not that it's difficult, just unnecessary.

The alternator will keep up with it, so you can drive if need be, it'll just run cold, and if the coolant sensor isn't functional (the one on the T-stat housing with two wires), you'll have capitalistic gas mileage.

Best of Luck!

Mike

[hewhobarksatdogs]

That was, indeed, the cooling fan relay. I opened it up and it is doing what it is supposed to. Open until I fire up the engine, then it is getting voltage to close the relay and the fan comes on. I will try the codes in the morning. Thanks to everyone for their assistance. If it were not for this forum the car wouldn't even be running. As soon as I get a few $$$ I will become a forum supporter. Hmmm, but then people will expect me to know stuff {:>)

---------- Post added at 10:19 PM ---------- Previous post was at 10:18 PM ----------

Oh, and where can I get a scan tool?

[zin]

---------- Post added at 09:23 PM ---------- Previous post was at 09:20 PM ----------

[/COLOR]Glad you're making progress, and glad we could help you keep one more on the road!

EBay is probably the best place to find one, assuming no one has one for sale here ... the best choice would be a DRBII, as that is the one made specifically for our cars, but the OTC4000 or 2000 will work too. The more generic 2000/4000 also work on other makes, so if you have other, non mopar, pre-OBDII vehicles, they may make more sense.

I don't recall which cartridge you'd want for the OTC, maybe someone will chime in with that tidbit.

And don't worry about "knowing stuff" as you go you'll find your experience lets you help those that haven't done what you've done.

Mike

[RoadWarrior222]

Beware the cheap "Chrysler code scanner", it basically only does what the "key dance" can do, with the CEL. Some of them are little more than a light in a big housing, that just connects a couple of pins, and you still have to count flashes, haynes manuals show you how to do that in case your CEL is burned out... these might retail along side other make OBD-1 scanners at the same price, that actually do stuff, like sensor and actuator checks, and actually store codes for recall. It's a little annoying that because the "flashy light" method means you can get by without a code reader on Chryslers, that you can't get a cheap scanner with more functions, but you have to go to a spendier one... Compared to needing one for codes on a Ford, but getting one for $50 that can do quite a bit.

[hewhobarksatdogs]

Did the key dance, got a code 35. Couldn't find anything in the Knowledge section so Googled it. Got a great link:
http://www.allpar.com/fix/codes/sensors/fan-relay.html
Guess I've got some work to do. Will have to wait until this weekend, I think. The wife will be driving me back and forth to work. "Are you ready to get rid of that car, yet?" "Well, you have problems and you're still here." Good thing she thought that was funny!

[RoadWarrior222]

Another good resource is ...
http://minimopar.knizefamily.net/index.html

[hewhobarksatdogs]

Thanks, RDub!

[shadow88]

Just thinking aloud here. You may have caused the code by unplugging it for your testing purposes.

[looneytuner]

Having many senior moments, my thought is the defroster is on in default mode which kicks on the fan because the a/c is turned on.
Ask me how I melted the black fusible link last week with a dead battery!

[hewhobarksatdogs]

Mystery SOLVED!!! Thanks to all, and special kudos to "looneytuner". The defrost button was, indeed, depressed. I turned on the car, watched the fan spin up, selected "bi-level" on the climate control console and the fan stopped running. I am much relieved because I was not looking forward to working on the car this weekend. I may have caused the code 35 when I disconnected the plug. How do I reset the code computer? I do have one question, though; why, in the name of the Great Gargoyles of Notre Dame, does the A/C come on when the defrost button is depressed? Looking for warm air on the windshield, not cold air. Can someone give me a clue on why that is?

Oh, and LT, how DID you melt that black fusible link with a dead battery???

[85boostbox]

The A/C is turned on with defrost cause naturally when a window fogs it is because of humidity. The A/C gets humidity out of the air.