Rad fans come on even when car is cold? wtf.

[GrandAmMe]

Ok,

This car is leaving me with a few question and this is one of them. This morning i went out and started my car....We got about a foot of snow so while i was brushing it off I hear this loud fan sound. I assumed it was just the heater fan But when I opened the hood I looked and yeah it was the Rad fans spinning away. I did ask my Tech teacher and he said it is because I had the De-froster for the rear and front on. I did notice the fans go off when i had the HVAC selected to any other position except the defrost position. So, Why would they come on when the car is cold and hot? Is it just cause of the defroster?

Thanks guys.

[Haughee]

I believe when you have Defrost on the A/C kicks on to take the moisture out of the air. Someone can correct me if I am wrong. When the A/C turns on the Fans come on with it. That is why the fan is running when the engine is cold and only when you have the defrost selected.

[350rs]

correct. that AC system makes a lot of heat and takes extra effort from you engine, making more heat. So the fans kick on kinda as a just in case kinda thing.

[GrandAmMe]

kk thanks guys! Just wanted to make sure. I also just got my car rustproofed so I was a little concerned cause they oiled EVERYWHERE under the hood. Its nasty.

[stewartfn18]

i have a similar problem, however, when i replaced the con rod bearings, i couldnt connect the harness to the compressor because the prongs are all jacked. didnt think it would cause a prob, but is this y my fans are coming on???

[GrandAmMe]

Ok so again another Weird thing. The heat from the vents is no where near as hot as it should be....and the rad fans still run. Heater-core? Temp gets into the regular operating zone. Im starting to think When i got the car undercoated the guy who did it messed with something that should not of been touched. What would I do if thats the case. Im absolutely disgusted with the mess of oil that is under the hood of the car.

[350rs]

he may have pulled a vac line or something.. take it back.

[GrandAmMe]

Ok,
so now i noticed the temp gauge doesent get up to its normal zone at all. About one good section before that. Im leaning towards a stuck open thermostat?

[KhellendrosxS]

Originally Posted by GrandAmMe

Ok,
so now i noticed the temp gauge doesent get up to its normal zone at all. About one good section before that. Im leaning towards a stuck open thermostat?

If its not getting all the way to ~220* then your thermostat is probably stuck as you suspect. Its a bit of a PITA to change but not outside the ability of a DIY mechanic.

[350rs]

during the winter a stuck open thermostat isnt such a bad thing.. other than poor heat. in the summer months though thats a VERY bad thing and can result in engine failure from overheating. Get it fixed when you can.. but your not in a super rush at the moment. Might be a good time to check your fluid condition too. Maybe do a full flush on the system since the thermostat has to come out to do it anyway.

[2000 GT Coupe]

Originally Posted by 350rs

during the winter a stuck open thermostat isnt such a bad thing.. other than poor heat. in the summer months though thats a VERY bad thing and can result in engine failure from overheating. Get it fixed when you can.. but your not in a super rush at the moment. Might be a good time to check your fluid condition too. Maybe do a full flush on the system since the thermostat has to come out to do it anyway.

I believe you have that backwords, a stuck closed thermostate would be a very bad thing during the summer, during the winter if you live in a super cold climate is not as bad.
In the -20F temps we have been having my coolant temps get to 195, maybe creep up to 200 but that is all. And that is even with card board almost completely covering the rad. Of course I have the pcm programed for a 180 t-stat.

[350rs]

stuck closed is worse. But stuck open your coolant is constantly circulating. Not giving it enough time to cool in the radiator. Sure it will cool a litte on its course through the system then back in.. but eventually it will just become hot all over.

[2000 GT Coupe]

Originally Posted by 350rs

stuck closed is worse. But stuck open your coolant is constantly circulating. Not giving it enough time to cool in the radiator. Sure it will cool a litte on its course through the system then back in.. but eventually it will just become hot all over.

I dont recommend this on newer cars, the computer would see the temp lower then it likes and try to do something about it, but on many older cars and trucks I have run with no t-stat. during the summer is the best time for that, during the winter it does not allow the engine to warm to sufficient operating temps and then your mileage and power do take a nose dive, and worse then that you do not get warm air out the heater.

[350rs]

correct, i wasnt going to go that deep into it however. but yes you are right.

[GrandAmMe]

Ok,

Sorry for the bump. Just thought I would keep you all up to date. After I got home from work which is a good 30 min hwy drive I immediately opened the hood and felt the rad hoses. The hose that comes right out from the thermostat housing is warmish-hot and I can leave my hand on it all I want and I probably wont get burned. The pipes coming out of the coolant tank, lower rad hose, and other hoses felt luke warm and almost cold. I can even touch the heat shield for the exhaust for about 5 seconds before it hurts. Not to mention The temp. Gauge only moved 2 bars from nothing!! I notice a very loud "TING" sound coming from the thermostat area after the car has been shutdown when warm. Im guessing its a stuck thermostat trying to do something? This still wont explain why my rad fans are always on high. Maybe my computer is getting really confused? I plan on calliing the "master mechanic" and getting this fixed. Im hoping this won't cost too much. Might as well go green coolant too while he will have to drain all the coolant right?

EDIT: So Basically I can put my hand anywhere I want on an engine that has been running for 30 Mins. Something is def. wrong with that. Ill keep you guys posted.

[KhellendrosxS]

Dexcool maintained at proper intervals has nothing to do with gasket failure and sludge. Its people that forget to flush it and/or ignore the signs of a gasket leak that have problems. Green coolant has to be flushed more often. Stick with what was in it.

Sounds like the ehaust heat shield is doing its job. Its in place to keep you from burning yourself on the very hot manifold. There is a lot of air swirling around it as you drive so of course it will not get nearly as hot. As the car sits when shut off its temp will rise slightly.

The ting sound you describe is most likely the result of contracting metal parts as they cool. I dont believe Ive ever heard an engine that didnt do this when shut off. Especially when it is cold outside.

Your symptoms do point to a stuck open thermostat that is not opening and closing properly. It seems that it has probably failed in the open position (which it is designed to do) and keeps the car from overheating which would happen if it got stuck in the closed position. This is good for saving the engine but not for generating heat for you.

Changing the termostat is a bit of a PITA but is easily doable in an afternoon with simple hand tools and it is a rather cheap part to replace. No need to replace the one you have with a lower temp thermostat. Not only will you loose some of the 'hotness' that your heater puts out but your gas mileage will suffer too.

[GrandAmMe]

Ok. Now will I have to "burp" the system after changing it? I really dont want to have to loosen the screw at the top of that black rail because it is VERY rusty. How much coolant will I Have to add afterwards? Do I really have to drain it all out of the rad?

[KhellendrosxS]

If its due for a service you have to remove all the coolant.

The screw on the tower is made of brass and should not be rusty...if its just the tower I wouldnt worry about a little surface rust. Its actually a pretty thick tube and if its in danger of disintegrating you should replace it.

[H.O. Driver]

or you can drive it for a little bit and all the air bubbles will make their way to the resivoir causing your coolant lever to get low, and then you can just top it off after the bubbles make their way out. However air bubbles on a full operating temp car can be bad since the air will be much hotter than the fluid in the hoses and motor causing huge jumps on the temp gauge.

A saftey thing programmed into the car is if the temp doesn't get up to a cetain temp, the PCM will read that the temp sensor is not working properly and will command the hi fans to run all the time to help prevent over heating.

[GrandAmMe]

Originally Posted by H.O. Driver

A saftey thing programmed into the car is if the temp doesn't get up to a cetain temp, the PCM will read that the temp sensor is not working properly and will command the hi fans to run all the time to help prevent over heating.

That makes alot more sense now!