Hmm, I should change that to "turn on the AC and one of the fans will kick on" For some reason i thought it was programed by GM to kick on the secondary one so it gets some use... I could be wrong.
the point is the same, regardless of which fan the AC turns on.

I agree with kicking on the cooling fans at a lower temp than factory... I think 160* tstats are overkill, but to each his own

Jonathan

 

OK. I'm not saying that the factory fan setting's are the best, just that if everything is working ok you should not be having a boil-over issue. Can you program them down a few degree's...of course, and you probably aren't going to hurt anything, the high setting from GM are due to emissions more than anything else. If you use a reprogram to 'fix' an over heat issue you WILL have a BIG PROBLEM sooner or later as you never addressed the real problem in the first place. Like a stuck T-Stat or a clogged radiator or heater core, or a collapsed hose, or a impeller going out in the WP, or a bad mix of antifreeze, or a bad cap, or a pin hole in a head gasket. Not trying to piss anyone off here just trying to pass on some real world 40+ years of playing with cars to some of the younger crowd, believe me I have jury-rigged/ rednecked just about anything you can on a car over those years...lol.

We here cannot tell what shape guy's car's are in. I think alot of these guy's just see the gauge go up more than normal once and a while and don't take into account what kind of driving they are doing at the time. These cars are 15+ years old, mine is pretty much stock and I pay attention to the cooling system a bit more due to our summer heat here. I ran my car for about a week on just the sec. fan in the middle of summer. It was fine on the open road, but in city stop & go it would get with-in hairs of the red before that fan would kick in, plus at idle the WP isn't flowing at peak...the one reason I may go electric soon. It still never failed me and never boiled over.

 

Sweet9C1, the primary fan ALWAYS comes on before the 2ndary fan, unless something is wrong with the fan circuitry - it's the primary fan.
When the AC is on - not just requested, but actually ON - the primary fan comes on @ 189 psi, and the 2ndary comes on @ 240 psi.

GM programmed the fans to come on at approx 229°F (primary) & 234°F (2ndary). If everything else in the cooling system is working properly, then those turn-on temps are on the high side of acceptable. (In other words, technically, I can agree with Gregg-O and GM.)

That said, and regardless of the condition of the cooling system's components, can anyone - ANYONE - plausibly explain why fan turn-on temps of, say, 220°F & 225°F are a bad idea?

I personally prefer fan turn-on temps of 203°F & 212°F for the winter (with the 180°F thermostat, of course). Are these temps a bad idea?

I'll admit that a 160°F stat with turn-on temps of 185°F & 194°F are unnecessary, but Gregg-O, have you tried 'em? The engine doesn't seem to mind - maybe because I deleted all motor oil cooling provisions except for 0W30 - and my AC blows colder in the summer for it. (NYC heat AIN'T a dry heat.)

Lately, a lot of people are complaining of overheating. Unless the needle actually touches 'the red', they may be exaggerating [if only by just a bit], but they are experiencing unnecessarily high [head] temps [as reported at the dash temp gauge].
If the [dash temp gauge] needle is 7/8 to the right, that's enough already.

Please don't take any of the above the wrong way. I'm actually asking the above questions in the hope of reasonable responses. Until then, I consider fan turn-on temps of 203°F & 212°F preferable to the point of general recommendation. Further, I'll admit that colder turn-on temps may be unnecessary, but there's a wide gap between 'unnecessary' and 'overkill'. Same goes for the colder thermostat.

 

With all the new school cars after 96, they make the fans come on at the halfway mark. Sounds like a pretty good idea with re programming these big bullies we drive. Ya know!

 

On my '96, the fan relay sockets were in bad shape. The fans would come on for a visual inspection, but in reality, they were not turning at full speed due to the voltage passing through the relay sockets to be lower than 12v.

Head temperatures would drop when vehicle speed increased. That turned out to be the major clue.

Innovative Wiring's fan relay kit cured that problem...plus new fans.

-KP

 

I'm having the same problem my fans won't kick on... And I can feel the heat when in driving in the city.

What should I do? New thermostat? And my A/C does need to be recharged by the way

 

I stand corrected many times over, my bad. The PRIMARY fan should kick on when the AC is turned on.

Cletus, you are making a mountain out of a mole hill... Yes a bad pressure cap is not good, Yes Steam in the water pump can cause a problem, Do I still say that it is VERY unlikely, and if that happens you have bigger problems than just a cap? YES Either way, replace the cap as stated. Then look to the bigger problem. There is a bigger problem.

If your car is getting hot enough to boil the coolant and water mix (assuming correct ratio etc) You need to address the issues.

That being said, back to the fan issues at hand. Onve you've ruled out the obvious, Charge your AC and see what happens (assuming both fans kick on when you unplug the coolant temp sensor which means the fans work, and the fuses and relays work)
Make sure you know what you are doing when charging AC (obviously) Once that's done, see what happens.. (assuming you've already done all the regular stuff below)


Make sure all aspects of the cooling system are in good working order, ie Tstat, mixture, pressure cap, and make sure radiator/ heater core etc are clean and not all gunked up..
Also it is a good idea to take the plastic piece off of the top of the radiator, and take a pressure washer and blast all of the bugs leaves crud etc out from both sides of both radiators and inspect to make sure the radiators are in good shape, fins aren't flattened etc.. Obviously make sure there isn't air in the system.

Once you've done everything, and it is still getting hotter than you want. Have the Temp settings lowered for the fans! It is NOT rednecking it. Do it when you are getting programming done regardless of whether or not you are having over heating issues.
Jonathan

 

@ Issac, If your car is over heating AND the fans are ON, then it might be a Tstat stuck closed.
If the car ONLY over heats when you are stopped, and the fans are NOT kicking on, Then it is not the tstat.
If the engine temp drops when you are driving to normal levels, Then the Tstat is open, and coolant is flowing. Then the temp shoots back up when you are stopped, that means air is not moving through the radiator, which means the fans aren't kicking on.
See previous posts.

 

I had the same problem car would overheat and the fans wouldn't turn on so I did a few things to narrow the problem and to save a few dollars so I wasn't replacing parts that were good . 1st I tested the fans by jumping the relay out they came on so fan relay and fan motors were ok Still Overheated. 2nd I flushed out the entire cooling system and bled it out Still Over heated . Finally I removed the stat and again bled out the system car never got past half so it whinded up being the thermostat. I also can say from personal experience if these cars are not bled out properly they tend to run a few degrees warmer than usual. Hope this helps

 

out of all these posts nobody has said anything about it being his temp sensor for the gauge. Wow, i mean really, have they had it hooked up to a scanner to see for sure what temp it's at? I have no A/C hooked up in mine and both fans work. Gauge would go into the red and still no fans on. actual engine temp was 180s. Overlooking a 15 dollor sensor seems stupid if you ask me. I'm so cheap i havn't even changed my sensor, it's just unplugged so i don't even look at the gauge anymore. haha

 

Hmm Perhapse you could have brought that up 3 pages ago?
Several people were talking about boiling coolant.. not the O.P. Who was concerned their fans were not comming on... though I suppose if the CTS in the side of the engine were bad, it wouldn't read in the normal range when driving down the highway..

Edit, I lol'ed at the "temp gauge unplugged" So to save a $15 part you are risking your entire engine? talk about cutting off the nose to spite the face!

 

sorry dude i don't spend too much time on the forum. I'm not worried about my engine at all man. i have a scanner and can tell when somethings goin wrong with a car usually. Mostly i havn't put the sensor in cause i put a fleetwood engine in with 60k on it and the sensor connector is different then my 9c1. after 3 sensors that all have the wrong plug i just didn't care anymore.

 

Well when I was driving yesterday it was hot and One fan was on but it was hot. About 3/4 almost in "red zone" but only one fan was on.
Is it the thermostat?

 

Which fan was on? The passenger side?

3/4 of the way up the gauge is not overheating. With a stock tune, these cars run hot as the fans don't come on until 225 and 232 F, which is past the halfway mark on the gauge. Also, temp gauges are not linear. For a GM gauge, the lowest mark will be 100F, half way is 210F, and pegged hot is 260F.

 

You need to verify your gauge accuracy.

Can you roll it in to a shop or AutoZone that has a decent scanner and check the temperature that the computer is seeing?

Or order one of these:

http://www.ultra-gauge.com/ultragauge/index.htm


If you unplug the ECT connection, do both fans come on after a few seconds? They should be turning fast and blowing hard. Check that they're blowing HARD.

The thermostat cannot prevent the fan from turning on. Only the computer can.

-KP

 

My passenger side was on but not the driver side
And the gauge was around 3/4

 

The passenger side is the Primary fan. It turns on first. The factory turn-on setting is ~225 degrees. Secondary is over 230 degrees. There's a turn-off setting as well. I'm not sure what it is exactly. The Primary fan should also be on whenever the A/C is activated.

Is the primary fan blowing HARD?

It really seems like it's NOT BROKEN!

You need a scan tool to check the REAL temperature.

-KP

 

right. understandable, tried that.
forgot to add, im just not that patient

 

I had the same problem replaced thermostat, water pump, flush radiator still overheats, reprogram fans for low temp gauge still reads in the middle, final i removed the cluster and installed another one and that fixed the problem, now my temp only goes up 1/4, smdh all that work i did and it was the cluster the whole time. lls

 

Umm, a temp gauge reading in the middle when warmed up is completely normal. With a stock tune, seeing the temp gauge climb to 3/4 is normal. Does the temp gauge needle on your 'new' cluster peg violently when you start the car? If so, the needle has probably begun to rotate on the shaft. Sooner or later it will stop registering at all.

 

I have 285000 mi. on my original 96SS and had to replace the fan motors twice when the fans quit working. Maybe its the fan motors.
This cap discussion is confusing. The cap seals the rad and has some spring pressure to keep from popping off under pressure. How do you get steam forming in the cooling system when all the air is bled off ? In order to get steam in the system there has to be void space for the steam to expand into. No void space, no steam. That is the reason for the air bleed valve. A bad cap will leak so if its not leaking it is still making a good seal. Steam will form when you have a hole in the system and the coolant squirts out then becomes steam because it is no longer under any pressure. Steam will not form inside the system at any temperature as long as there is no void space but if the temp gets high enough something will pop because pressure builds up in the system due to expansion of the overheated coolant (overflow tank handles the expanded coolant) and then you will see the steam spraying all over the engine. Sometimes when you overheat the heater core will pop and leak all over the front floor due to the increased pressure inside the heater core. Otherwise a great discussion!

 

In order to get steam in the system there has to be void space for the steam to expand into. No void space, no steam. That is the reason for the air bleed valve. A bad cap will leak so if its not leaking it is still making a good seal. Steam will form when you have a hole in the system and the coolant squirts out then becomes steam because it is no longer under any pressure. Steam will not form inside the system at any temperature as long as there is no void space but if the temp gets high enough something will pop because pressure builds up in the system due to expansion of the overheated coolant (overflow tank handles the expanded coolant) and then you will see the steam spraying all over the engine.

Incorrect, sir. Steam will form any time the temperature of the coolant exceeds its boiling point at that pressure. If the coolant cap no longer holds pressure, then the coolant will boil if it gets hot enough, usually escaping through the coolant cap.

 

So, if the coolant cap is not leaking there is no problem with the cap and the coolant will boil over into the overflow tank. Correct?

 

heating problem

hi there i was reading this post i have the same problem but my fans do kick in when the temparature is hot how can i reprogram the the fans to 10 degrees lower

 

You have to have the PCM retuned. Why do you think it's a problem? If your fans kick in when the temps goes up, That's what they are suppose to do.

 

95 Impala OVER HEATING.. Fans WONT come on.

Another common cause of over heating are broken,and/or missing air-dams. Small air bubbles form between cylinders all the time,proper functioning cap forces them to stay small,and along with the bleed pipe continually remove them.Weak coolant encourages this situation,so does poor coolant flow. As soon as cylinders get more air bubbles around them,they get really hot,and so on,and so on.

 

LOL,

I have the same problem. Mine started about 3 months ago but I don't drive the car much.

I am going to pull the CTS and see if both fans come on.

I did find the relay connection highly tarnished.

 

dont jump

Everyone jumps to conclusions, well it was this for me, it was this or that try this, and by the end, everyone is off subject. The original question was his cooling fan was not coming on and his car was over heating. Nothing about boiling over.
In order for his car to be over heating, he must be watching the gauge. Assuming it is correct, His fan would have been on long ago. Because the computer is seeing the temp is way to much. Everyone states great facts and tips and tricks but danced around what he had actually said.

 

Well I have about the same problems,and now i know a quick little test which is the AC on test,the only other one i know..because the car sits around for yrs is the sensor for turning the fans on..plus i have one of the computer programmers for this car from the superstore...i wonder if the setting for turning the fans on earlier is easy to find,but i like to dig...so digging for a bad sensor will be a next step,plus the manual on trick may do for awhile,might only need a heavy duty switch inside the car for doing that,all kinds of stungs to do,i figured it was the thermostat goin bad..well 23 $$ at local canadian tire store haha,nah i think i will test that while i have it out for opening and closing under either hotwater via propane torch or torch alone..plus a little humour...if u do not change the coolant from the day it was brand new,will that make it go rusty! 1996 to 2013 ?? lol bad me...anyway renewing all fluids and playin with the temp sensor plus a lot of things,i just got the car inspected and was runnin ok when on the road,idle in yard and temp goes up to midway point,got cold water runnin in from hose and it stays low so there u go..anyway read all the tips...the AC is my first to see if fans come on..thanks Eric on 2013 08 16