: I have searched and searched, still no answers please help!



lunchbawks
09-08-11, 02:03 PM
I have been searching google and these forums for a quick answer for my problem, (at least i think its a problem) my 95 brougham starts and runs fine, until it heats up, then it starts chugging, i thought it was a cooling problem and noticed that the drivers side cooling fan is not spinning, It was shot and i replaced the motor for the drivers side fan thinking that it would turn on as soon as the car starts, it did not, so i replaced the thermostat thinking that the drivers side is a backup fan for when it gets to running temperature and my problem was a stuck thermostat not triggering the secondary fan to come on. so what i am wondering, is if the drivers side fan is supposed to run all the time or if it turns on intermittently when it gets hot enough. or if i should be looking for a short in the wiring to keep the fan on all the time.

I have checked for all the classic signs of a bad head gasket and do not see anything, however, When the car gets hot, the radiator fluid starts boiling over the overflow reservoir. is that normal, or did i overfill the radiator, or do i need a new cap?

turbojimmy
09-08-11, 02:34 PM
The driver's side fan is the primary, the passenger side is secondary. Here's what the factory service manual says:

This two fan system is PCM controlled by inputs received from the engine coolant temperature sensor, vehicle speed sensor, and the A/C system. The PCM commands the primary cooling fan On when engine coolant temperature exceeds 225F, A/C head pressure is above 225 psi and when certain diagnostic trouble codes are set. The primary fan is commanded Off when engine coolant temperature drops below 217F, or A/C head pressure drops below 180 psi.

The secondary cooling fan is commanded On when the engine coolant temperature exceeds 232F, A/C head pressure is above 248 psi or certain diagnostic trouble codes are set. The PCM commands the secondary fan Off when engine coolant temperature drops below 224F, or A/C head pressure drops below 203 psi.

My car can idle in the driveway for at least 15 minutes without either fan coming on and it never gets hot. Does the temp light come on inside the car (indicating that it is indeed hot)?

Replacing the thermostat won't make the fans come on. There's a sensor mounted in the water pump housing that sends information to the engine management computer (the Powertrain Control Module or PCM). This is how it decides whether to turn the fans on. If it only overheats when idling, and neither fan is coming on, then I would guess it's the temperature sensor. You can see what the reported coolant temperature is through the HVAC controls. See the FAQ for entering diagnostic mode, I believe selecting #8 is coolant temp in F^.

If it overheats while you're driving, then you may have bigger problems. Air moving through the radiator above like 35 MPH is usually plenty to keep the engine cool without the fans running. The PCM actually shuts the fans off at certain speeds.

lunchbawks
09-08-11, 03:54 PM
Thanks so much! that was so much help, the car is not showing anything stating that it is overheating, but thats just from looking at the idiot light and i have not entered diagnostic mode yet. but after i changed the thermostat, i replaced the coolant that was lost in the process and it is now throwing a low coolant light although it is not low. i also decided it would be a good idea to check fuses and found that the air pump fuse was blown. its been in the driveway running for a while and both the fans were running properly while at running temp. Im going to go enter diagnostic mode and check to see if i can find anything. although i did all that work and both fans are now working, i am afraid that i will stall on the road and have to get towed again, i should mention that i have not had any problems until i get stuck at lights or if i leave the car on in the parking lot so thats what led me to believe that the motor was not being cooled properly.

outsider
09-08-11, 04:20 PM
Did you fill the system with the bleeder screw open? If not, I wonder if air in the system could be causing problems?

turbojimmy
09-08-11, 05:01 PM
Did you fill the system with the bleeder screw open? If not, I wonder if air in the system could be causing problems?

That could be, too. If you do need to top it off, do it when it's cold and with the bleeder open. I posted the fill procedure here not too long ago.

The switch for the idiot light is in a stupid spot under the exhaust manifold on the passenger side, above the starter motor. The connector and sensor get crazy hot and brittle. They break off. The one on my '96 and '94 were both broken off, eliminating the idiot light. The light will still come on with the key-on bulb test, but not actually light up when it's hot. I bet your car was overheating but you've got no light.

If the fans are running now, and it's not overheating then it sounds like it's good for now. I'd be a little worried about what caused it to overheat in the first place. A thermostat stuck shut would do it, but both fans should have been running.

EDIT: Oh yeah - if it's getting hot at lights and in parking lots, then it's a fan thing. Why is the question....

HUF
09-08-11, 09:01 PM
Lunch,

You are overreacting. Nothing is wrong with cooling system, just bleed it properly. The first fan turns on whet temp reaches some 226 and the second one whet it is really hot (around 265 as far as I remember).

The low coolant sensor is known to malfunction on these cars. Ignore it and check the level from time to time.

You can monitor coolant temperature by turning on board diagnostics on, choosing parameter 08. It usually shows 180 in my car while cruising. If you stop it will climb up slowly. I can recall barely a couple of occasions when my cooling fan would kick in.