Hello All!

I was wondering where your temp gauge normally runs...

With the weather getting warmer in my neck of the woods,
my temp gauge has been running in the half to 4/5ths range
of the gauge (the higher mark is with the A/C running).

This is in-between the "slash" marks on the gauge which I
assume is the "normal" range.

Does this sound normal or a little high?

Can the temp sensors that turn the fans on be change to a
sensor that has a lower setting so the fans turn on sooner?

Anybody tried a thermostat with a lower setting?

Thanks!
Scott

 

Your gauge should always run abut mid mark(halfway) around there as long as its no where near the Hot or H area youre ok.

 

It runs halfway or a little over under normal conditions,
but up to about a 1/4" down from the slash mark near the
H when the A/C is on but never goes any higher.

Thanks!
Scott

 

Even with the A/C on it should still stay at half way or less. Actually when I turn on my a/c the car gets cooler temp wise. When you turn your a/c on are your fans coming on too, if not then that could be your problem and thats why when the a/c is on it gets hotter. Plus when was the last time you changed your thermostat.

 

Well, with my car, I run from mid range to the last mark before the H. I've flushed my cooling system (though I may need to do it again, or look into a new thermostat). As long as the needle stays with in the 2 marks (one just after the C, and one just before the H) you'll be alright, as that is the normal operating range. You might want to check your cooling fans just to make sure they are even coming on. I know for my car, when it runs the temp gauge is at normal to almost the last mark, it will run the main fan, but when it gets hot enough, both fans kick in. Also when you run A/C, in fan setting 1 and 2, the main fan should run constantly, at fan setting 3 and 4, both fans should be running. If your fan's aren't working, you need to check the fusible links for both fans. The main fan fusible link is along the driver side fender with the other fusible link. It has a green with orange tab harness. The secondary fan fusible link is on the positive battery terminal, the harness is also the same color as the main fan. Also, you might want to check the condition of the fins on the radiator and make sure they are restricted or anything. That could cause some cooling issues. Also you may want to look into a new thermostat, just incase your is not opening all the way or stuck closed.

S

 

I've watched the fans as I turn on the A/C...

The larger one turns on right as I turn on the A/C,
but I haven't seen the smaller one turn on which I was
told by a dealer should turn on with the A/C.

The larger one turns on also when the engine temp rises
to the mid point on the gauge.

I have tried replacing the relays to the fan (I picked up
an 87 sedan that had been hit hard in the passenger side
for a $100, makes a great parts car! Already earned it's
keep).

Should the smaller fan turn on with the A/C?

Next step I was going to try the fans from the parts car.

Thanks!
Scott

 

Hmmmm... I didn't check the smaller fan with the A/C fan
on the 3-4 setting... I just check it by turning the A/C
on.

I have to look into that one.

I'll have to check the fusible links as well... good to know.

I have a new thermostat and gasket, just haven't gotten around
to getting it installed yet!

I'm thinking it's okay because the engine temp only rises really
high with the A/C on, but I'll replace it anyway for piece of
mind.

Thanks!
Scott

 

Mine is doing the same thing now that it's warmer out too, especially if I'm idling for extended periods of time. It usually runs between halfway and about 3/4 of the way to the overheat line. In the winter, it was running at a 1/4 to half, never got beyond half way though.

It didn't do it last summer, so I'm attributing it to the fact that I'm long overdue for a flush and fill. Plus, when I was low on coolant a while back, I just put water in the system instead of the 50/50 mix.

Well, do as everyone suggests, flush and fill your system, make sure you get the proper 50/50 mix of coolant/water. That may bring the temperature down. You could run a thermostat that opens up at a lower temperature too.

You could set the fans up to come on when ever you wanted, hell you could leave them on all the time if you wanted to, though you will burn up the motors quicker than usual. You'd have to disconnect the existing wiring and run some of your own wiring, connecting it to a switch, relay, and to the battery, similar to the way you'd hook up fog lights. Just don't forget to turn the fans on when you start up the car!

-C-

 

You don't know of any temp sensors that I could put in place
of the stock ones to make the fans come on a little sooner?

Flush and fill is on the list... item number eight I believe!

Thanks!
Scott

 

I don't know how it's setup, but I don't think you have to change out the sensor, rather you'd have to adjust (or replace) the computer that reads the signals and determines when to turn the fans on and off. That's assuming it's electrical, which I would think it would be since the fans are operated electrically. If it's mechanical, then I don't know how you'd do it.

But like I said, I don't know how it's setup and what computer would monitor that sensor, could be the ECU, not sure.

You could setup your own temperature sensor if you wanted though. You'd have to get a thermosistor and put it some place where it could get an accurate measurement of the coolant temperature. Then you'd run that wire to a computer that would also connect to the fans. You could then adjust that computer to the temperature that you want the fans to be activated at.

It's pretty complicated and I don't know of anyone who's done it before on a car. Most people just leave the fans alone. I've done that sort of stuff on comptuers to monitor the temperatures of the various components, to test the cooling efficiency of the machine, and to reduce power consumption, but I've never done it on an automobile.

-C-

 

Yeah, the sensors just merely take a temperature reading and send it to relay, which determines whether the fan should turn on or not. Quite honestly, a really good flush, a new thermostat, and maybe removing the radiator and cleaning out the cooling fins will probably do you good. You can also wire your fans to run on when you flip a switch. Quite honestly, I wouldn't do too much, so long as the engine isn't overheating (when the needle is fully at H).

S

 

Actually the sensors close a circuit when they reach a certain
temp. The circuit closing switches the relay to turn on the
fans.

Like Charles said, they are a thermistor style sensor.

I was just curious as to if anyone knew what the stock
setting is (meaning the when the first fan turns on?
160 degrees? 180 degrees? When the second fan turns on?
200 degrees? 220 degrees?), and if there were any sensors
that might turn on sooner (like 150 degrees for the first
fan and maybe 180 degrees for the second).

Looks like I'll have to check with the dealer...

Thanks!
Scott

 

Dang Ive been reading you guys posts. My car runs the big fan when the temp gauge moves alittle more than half way and then once its cool it turns off. When the a/c is turned on then the Small fan comes on automatically and the temp gauge actually goes between the C and half way always. I have just recently see my temp gauge try to move a tid bit past the middle but my fans always come on to cool it down. Ill check to see about that temp setting for the fans Sarin I dont know Ill check though. You could do what charles said about getting a thermisistor to get an accurate reading on temps and set it to make the fans come on sooner

 

I've got an '88 automatic, with the automatic climate control and a digital dash. When I turn on the A/C, both cooling fans come on immediately regardless of engine temperature. When I'm not running the A/C, both fans cycle on and off as needed to keep the engine from overheating. The temp gauge (digital remember) shows just past halfway when at operating temperature. Last summer, one of the fans burned out - the car didn't overheat unless I ran the A/C in city driving. It was fine at highway speeds with the A/C on even with the fan burned out.

 

Hmmmm.... the plot thickens...

Sounds like your car's set up is the way that the fans
should work.

My car's large fan turns on when the A/C is turned on or
when the engine temp gauge comes up to midpoint and shuts
off when the engine cools some, just like your car.

The small fan turns on when I turn the A/C fan motor up
to the 3-4 setting just like Sarin mentioned.

I assume (there's that word!) that the small fan turns on
when the temp gauge climbs up to the 3/4 mark...

Wonder why both of my fans only turn on when the A/C is
on and the fan setting is on 3-4?

Things that make you go hmmmmm...

Thanks!
Scott

 

mine too

 

The reason both fans comes on is the A/C system puts more of a strain on the cooling system. At settings 3-4 your asking for maximum cooling in the cabin, and this starts to really heat up the condensor at the front of the radiator. When this happens, there isn't as much cold air getting to the radiator, causing that to loose cooling efficiency. So the other fan kicks in to get more air through to keep both cool. When your at setting 1-2, the main fan brings in enough air for the 2, and your only asking for minimal cooling. Etc.

Those that help any?

S

 

Something else to make you go hmmm. You guys mention a large fan and a small fan. Both my fans are the same size. I kid you not. Anyone have any ideas why? My car is a floater if that helps, with the automatic climate control.

 

both of mine come on regardless of the setting 1,2,3,4

 

The design of the fans changed slightly in 87-88. They made them much more quieter. In my 86, the main fan is slightly bigger in diameter, and has 4 large blades, my secondary fan is smaller, but has about 5-7 blades on it (I haven't counted). I believe in the 87-88's, they all have the same size fans, but one has more blades if I looked out it right...I will have to double check.

S

 

I have a large fan and a small fan too. Ill check at lunch but Ive always seen mine as having a large fan and the smaller one to the right.

 

Ok here are the temps from the FSM

It states that the first fan (left fan big fan) is on at around 194 degrees Fahrenheit and the second fan( right fan smaller fan) come on when it reaches 212 degrees Fahrenheit or whenever the A/C compressor is on both fans are on because the temps are above 212 degrees so they come on to cool the car off.

 

Thats one heck of a run on sentence I did, lol

 

Also there are two temp switches. So Sarin if you can find some that fit on the radiator then you might be able to get some that come on at a lower temp. The first temp switch is located on the bottom of the radiator on the far left. And the Second temp switch is located at the top of the radiator on the far right. I beleive the fans are controlled by these two temp switches the first bottom one I believe is for the first fan and the second top right one is for the second fan.

 

I realize full well why the fans come on at the 3-4 setting,
but my concern was why that's the only time they both come
on?

max88q stated that his fans come on when the A/C is turned
on even if it's set on 1-2 and that his temp gauge never
rises above the mid point range...

Maybe this is the way the 86 Max fans operate/

Scott

 

That's how this whole thread got started... I was trying
to find out if anyone had found different sensors to use
to make the fans come on sooner!

It was stated that both fans should come on when the A/C
is turned on... my second fan only comes on when the fan
speed setting is at the 3-4 setting.

I'm going to change out the thermostat this weekend to see
if that helps cool it down some.

Thanks for all the replies!

Scott

 

I think the thermostat is your problem first to check. I changed mine out because when I first got the car it was running at around the H area. Changed the thermostat and it has been bliss ever since. Mid range all the way. Also I can tell when my car needs an oil change not by the miles or month wise but I notice that the temp gauge starts to wander alittle past the mid range area. Plus my car doesnt start up as Quickly too. Oh dont forget to drain the radiator. My dad forgot to before I got outside to tell him and it went everywhere. Plus when changing the fluid there is a bleed screw to let out any air that may be stuck in the passages. If this isnt done it is possible that air could travel to your water pump and get stuck there permitting Coolant to get by and ruining your water pump.

 

The drain plug should be on the passenger side of the Cylinder block and radiator. More like near the radiator its a cube looking thing with a circle *** to turn it.