850 GLT fan not working

satman1959 · Post by **satman1959** » 27 Apr 2012, 08:46

Hello all. This is my first time posting and I can't say enough of how great this site is. My college age daughter has a 1996 850 GLT, non turbo, 2.4 liter. I can run her car for about 20 to 30 minutes until the overflow gets high and the car begins to get hot, but the fan will not go on. Temperature gauge goes up to between midway or 3/4. The fluid is moving.
I turn on the AC still no fan. Unplug the ECT and the fan does go on. Tested the fan direct and it works. Grounded each side of the relay and the fan works according to the appropriate speed. So far, I have put in a new ECT, and thermostat. Checked the wires from ECT to Control Module and control module to the relay and they are good, tested the fan, tested the relay, they are all good. I even swapped the Control Module with a used working module, (same numbers and Bosch manufacturer). All the parts are directly from the dealer.
Also, after running for about 5 minutes or so, the idle is just a little rough, but if I accelerate, there is absolutely no power except an occasional surge. The only codes that come up in the OBD2 are indicating too rich of air fuel mixture, which from what I have read, the coolant temperature sensor can cause this if the car doesn't realize it's running hot, but again that's a brand new manufacturer sensor. I'm only a back yard mechanic, but I would think the fan should come on in that amount of time.
I am truly at wits end with all of this and any help or input would truly be appreciated. Thanks so much.

Post by **Ozark Lee** » 27 Apr 2012, 15:10

Welcome to MVS.

You have definitely done your homework and you have gone through all of the trouble-shooting procedures I would have suggested.

The temperature gauge getting up to 3/4 is well into the danger zone on these cars. The lack of power you describe after running for 5 minutes has me concerned that the car may have blown a head gasket.

When you turn on the A/C does the compressor actually engage and run? The fan won't be triggered unless the A/C has sufficient high pressure to tell the system it is on and operating.

From all that you have done the only thing I can come up with is dirty connections on the ECU edge connector but I'm not really buying that both fan speed pins would go bad at the same time.

I think my next step were it me would be to use an infrared thermometer to find out what the temps actually are after the car warms up. Harbor Freight has the infrared thermometers with the laser pointer on sale for $30.00 at the moment.

I just hate it when a first time poster stumps the guessers.

Good luck with it.

...Lee

satman1959 · Post by **satman1959** » 27 Apr 2012, 22:52

Hi Lee, thanks so much for the suggestions. I was worried at first about a blown head gasket also, but there is no big cloud of white from the exhaust, (a bit of blue, but that's a later headache), no foam on the oil dipstick and there really is no loss of antifreeze. The gauge for the most part stays at half, occasionally tips to 3/4 if I rev the engine and it's been on for awhile. If I run the fan manually, the temp goes down.

Good point about the compressor, no it doesn't actually go on, it is undercharged. When approximately should the fan actually go on? Keeping in mind that I don't have it on the road. I only let it idle for about a half hour or until the level in the overflow rises to near the top.

The power surge part was where this all started from, but the codes were all just generic indications of too rich a fuel mixture after the vehicle heats up,like (P0172 bank 1 system too rich), (P1310 manufacturer controlled ignition system or misfire), (P0300 Multiple misfire detected) and (P0102 mass volume air flow circuit low input) I replaced the MAF sensor last year. From what I read on all the codes it usually indicates a bad vacuum and or air flow so I replaced all the hoses and vacuum lines, new oil trap and flame trap. I removed the EGR and thrrottle control and cleaned it. The intake from the EGR to the Intake manifold was caked full of gunk. I put all that back together and it seemed to help a little bit. It acts almost exactly like it did when the MAF sensor went on it last year.
I am one for stumping people. Like my brother always said, you can always expect the unexpected with me.
Thanks again for everything....

satman1959 · Post by **satman1959** » 02 May 2012, 13:59

Here's my update. Thank you again Lee, you got me thinking about the actual temperature of the vehicle. I didn't get the chance to get that IR temp gauge from Harbor freight, (mens toy store as my son calls it), but I did do some investigating and found that the fan normally won't come on until about 200 degrees and running in idle for 20 to 30 minutes, it's unlikely the car ever reached that temp, (though I will still verify).

I investigated a little more, realizing that the only actual conclusive mechanical failure showing in my OBD2 readout was the low "input" to the MAF. I did replace it a year ago, but I remembered it was a re-manufactured cardone from Advanced Auto which I don't think is a dealer part. after more research, I found a quick test to unplug the MAF after it begins to run rough, which I did. It hesitated when I first restarted, but then it ran great, no hesitation or lack of power. I nearly spun the tires. Did this for several minutes and it was great. From what I read, this usually indicates a bad MAF and the fact that I got a non original manufacturer, rebuilt, I'm relatively confident this is the problem. Any input? Does this seem about right?
Thanks again for the input.

Post by **jblackburn** » 02 May 2012, 14:20

Your MAF does indeed sound bad - the remanufactured ones do not last long at all.

What color is your cap on the overflow tank? If it's grey or you see any cracking in a green one, replace it. It may just not be holding pressure as it should. The system needs to be properly pressurized in order to activate the fan.

The AC will not turn the fan on until it reaches a certain pressure as well (which it's not doing if it's low on freon).

satman1959 · Post by **satman1959** » 02 May 2012, 14:40

The overflow cap is grey, and I've never replaced it during the nearly 150,000 miles we've had it. The AC is definitely low on freon. Thanks so much for your input, I will look into replacing the cap. I'm sure 150,000 miles is about 100,000 more than the cap should have on it.

SHAKAMAMBUTU89 · Post by **SHAKAMAMBUTU89** » 02 May 2012, 16:14

I had the same problem in my old 94 glt. I went through a lot because of that car. From my experience on that car and from the mechanics i spoke to, they said that the fan was not turning on because the fan sensor was burnt out. In other words the fan isn't cooling the coolant because it isn't turning on in the first place.

I am not a mechanic but I hope whatever I said helps

Post by **Pauloil** » 02 May 2012, 21:48

not the fan sensor, but the coolant temp sensor under the thermostat. sometimes when the sensor goes bad, the fan runs too much!

SHAKAMAMBUTU89 · Post by **SHAKAMAMBUTU89** » 03 May 2012, 15:58

But if the fan runs too much then why would the car overheat?

Post by **Pauloil** » 03 May 2012, 17:43

the key work is sometimes. that what mine did when it was bad.