Cooling fan troubles, starting to get somwhere I think

[Rottweiler28]

I have a 94 Grand prix SE with a 3100. I recently did a head gasket job and all seemd to go well till I noticed about 2 weeks later that the cooling fans stopped working and the car started getting realy hot. I didnt replace the heat shield back onto the rear exhaust and am thinking maybe i melted a wire or something related to the cooling fans. I dissconnected the sensor right next to the throttle body under the accelorater cables (The 2 pin connector) and the fans will run this way continiously but I want to know how to fix this issue and get it working the way it should be. Any idea why it will work with this sensor unpluged and not work when plugged in. Wher might I start to look next. Any ideas would be greatly appreciated as usual. Thanks in advance.

[BNaylor]

When you disconnect the engine coolant temperature (ECT) sensor the fans turn on and will run continuously so that is normal. Although you changed the head gaskets did you do a complete cooling system flush? Other possibility is the ECT sensor itself or a problem with the thermostat.

The PCM module uses the ECT to turn on the fans based on engine temperature so at least part of the circuit is working properly. If your A/C is working, can you get the fans to turn on with A/C in the max position?

BTW - Also, make sure there is no air in the cooling system. Do another bleed job.

[Rottweiler28]

I have used a flushing agent and ran the car with it for 15 mins as was on the instructions, I then used a T connector attatched to the water pump heater core line and flushed the system out completly for 10 mins (This was done after I removed the thermostat). I then topped it back up and ran it with the cap off for 10 mins to make sure there was no air in the system. I have lots of heat from the heater. The AC hasnt been working since I got the car but im pretty sure it just needs to be charged, but no the fans do not come on when the AC is turned on. Any other ideas?

[BNaylor]

Originally Posted by Rottweiler28

I have used a flushing agent and ran the car with it for 15 mins as was on the instructions, I then used a T connector attatched to the water pump heater core line and flushed the system out completly for 10 mins (This was done after I removed the thermostat). I then topped it back up and ran it with the cap off for 10 mins to make sure there was no air in the system. I have lots of heat from the heater. The AC hasnt been working since I got the car but im pretty sure it just needs to be charged, but no the fans do not come on when the AC is turned on. Any other ideas?

Since you have a 3.1L there should be a bleeder valve on the tower mounting on the top of the water pump. This is the heater line. If not there check the thermostat housing for a air bleeder. A lot of times simply removing the radiator cap will not get all of the air out of the cooling system. Also, getting the radiator above the engine helps bleeding. Park it on an incline. Try bleeding again but with radiator cap on and engine up to operating temperature. Other than that either thermostat or ECT sensor.

[Rottweiler28]

Originally Posted by bnaylor

Since you have a 3.1L there should be a bleeder valve on the tower mounting on the top of the water pump. This is the heater line. If not there check the thermostat housing for a air bleeder. A lot of times simply removing the radiator cap will not get all of the air out of the cooling system. Also, getting the radiator above the engine helps bleeding. Park it on an incline. Try bleeding again but with radiator cap on and engine up to operating temperature. Other than that either thermostat or ECT sensor.

Ok, never did get the cooling fans working. I just dissconnected the sensor located kind of under the plenum. The fans run continuious now. Since I made this post I have been slowly getting less and less air flow (Heat or cold) through the car heater. Also now cannot change from floor to vent to window, seems to be stuck on window only. I do know this car uses electric/vacum actuators to open and close the doors to change from vent to floor etc.. But I have no idea where to check or what to check to fix this issue. No wooshing sounds when i try to blend, window only so something stopped working there. On top of this I put a new thermo in yesterday and it seems the car will hit red line (225 degrees and temp light comes on) overheat within 5 to 10 mins, even when driving with both fans running full bore. Now I am thinking that this is due to water flow restriction either in the rad or heater core. I have flushed 2X and same. Thinking on pulling the rad out and the heater core and giving them somewhat of a SUPER flush, heard javex works well. But the heat bleding issue is really getting me, I have no idea on these units, im used to the old fully vacum style cars and sliding switch cars. Also I am thing on replacing that sensor which when i unplug makes both fans come on to see if that gets my coolant fans working right again. Worse comes to worse I am going to simply pull the new thermo and block off the outter side of the rad with cardboard, will be a little cool but better then to hot. Thanks for all the help thus far, please keep em coming, getting cold here in NS.

[richtazz]

If you didn't bleed the air out of the cooling system after changing the T-stat, that is the problem with both the overheating and lack of heat issues. There are two bleeder valves, one on the t-stat housing, and one on the transfer tube near the water pump.
The inablility to switch modes is a vacuum problem. The vacuum comes from the intake manifold, goes to a check ball/reservoir, and then into the interior. Any cracks in the lines (they are hard plastic) will cause the modes to stop switching.

[Rottweiler28]

Originally Posted by richtazz

If you didn't bleed the air out of the cooling system after changing the T-stat, that is the problem with both the overheating and lack of heat issues. There are two bleeder valves, one on the t-stat housing, and one on the transfer tube near the water pump.
The inablility to switch modes is a vacuum problem. The vacuum comes from the intake manifold, goes to a check ball/reservoir, and then into the interior. Any cracks in the lines (they are hard plastic) will cause the modes to stop switching.

Ok i know for sure it is not a vacum problem as we checked the entire vacum lines and traced them for over an hour and there are no leaks, we also ran a vacum test which also showed no leaks. Also know it isn't air in the system as we purged the air out of both bleeders for over half hour with car running, ( the one by the tstat housing and the one across the way from it on the other side of the motor) I was told of a motor of some sort near the heater core which controls the doors to change posistions from floor to vent to window (Defrost). BTW it is a 3100 not a 3.1. I am getting heat to the wind shield (Defrost) but not so hot. I took out the t-stat so this i am pretty sure is the problem there. The reason I took out the T-stat is because I could not drive the car 5 minutes before it would over heat. I changed out the heater head control ( The dial unit for changing fan off and on, changing hot to cold and changing from floor to vents etc. It didn't make any difference. I had the car pressure tested today at the raditor and it held its pressure at 15 lbs no problem, and rose after i stared the car which is normal, did this to check for possible head gasket or intake leak. Next thing I am going to try is bypassing the heater core and putting the T-stat back in to see if the heater core might be gummed up. As far as little air from the vents I am willing to bet it is a plugged, grimey dirty evaporator dam which sits between the blower fan and the heater core. Only thing I am not sure of is the exact location of this motor said to be next to the heater core. Not sure if it is inside the heater casing or beside it. I can see the one which kind of looks triangular with wires running to it, I am thinking this might be it. To bad haynes didn't break the manual down a little further. Anyone know the name of this said motor I am looking for if it is EVEN a motor. Any replies welcome. BTW, tested the water pump and thats good to, if bypassing the heater core doesnt do it for me I will be swapping out the rad i suppose. Process of elimination sucks when it takes this long..lol. And both coolant temp sensors were tested and working fine. cooling fans still not working right. Thanks again.

[Rottweiler28]

I didn't get a chance to bypass the heater core yet but had the car running for bout a half hour today in the yard and was checking all hoses and such, lower rad and upper rad hoses were warm, rad was warm and only one heater core hose was warm the other was pretty much cold as could be, im hoping and praying this is the problem, gonna try and bypass the core tonight to see after I install the T-stat again then run her. Crossing fingers here. Also noticed one other thing, checked my oil and it is as black as coal (Burnt to some degree) would this be from driving the car so hot for so long? I'll let yas know what happens after trying the double bypass surgery..lol

[Rottweiler28]

Originally Posted by Rottweiler28

I didn't get a chance to bypass the heater core yet but had the car running for bout a half hour today in the yard and was checking all hoses and such, lower rad and upper rad hoses were warm, rad was warm and only one heater core hose was warm the other was pretty much cold as could be, im hoping and praying this is the problem, gonna try and bypass the core tonight to see after I install the T-stat again then run her. Crossing fingers here. Also noticed one other thing, checked my oil and it is as black as coal (Burnt to some degree) would this be from driving the car so hot for so long? I'll let yas know what happens after trying the double bypass surgery..lol

Well I tried bypassing the heate core to see if that was plugged but to no avail, still over heating When I dissconnected the heater core hoses I blew into one and there was no restrictions that I could feel at all, was like blowing through a 3 foot garden hose, now I am really stumped on this and am seeking serious professional suggestions if anyone has any, or any suggestions period..lol. This is crazy, ive done everything but replace the water pump (which we checked and IS pumping good) and the Rad which we flushed several times and there seemed to be no reestrictions there.

HELPPPPP!!!!!!!!!!

[Rottweiler28]

Originally Posted by Rottweiler28

I didn't get a chance to bypass the heater core yet but had the car running for bout a half hour today in the yard and was checking all hoses and such, lower rad and upper rad hoses were warm, rad was warm and only one heater core hose was warm the other was pretty much cold as could be, im hoping and praying this is the problem, gonna try and bypass the core tonight to see after I install the T-stat again then run her. Crossing fingers here. Also noticed one other thing, checked my oil and it is as black as coal (Burnt to some degree) would this be from driving the car so hot for so long? I'll let yas know what happens after trying the double bypass surgery..lol

Well I tried bypassing the heater core to see if that was plugged but to no avail, still over heating When I dissconnected the heater core hoses I blew into one of them and there were no restrictions that I could feel at all, was like blowing through a 3 foot garden hose, now I am really stumped on this and am seeking serious professional suggestions if anyone has any, or any suggestions period..lol. This is crazy, I've done everything but replace the water pump (which we checked and IS pumping good) and the Rad which we flushed several times and there seemed to be no restrictions there.

HELPPPPP!!!!!!!!!!