Automotive Forums

ok, so i have a 95 mystique gs 4 banger. its a pretty faithful little car. Only problem i have had since we bought it, is tends to over heat when we are sitting at red lights or in drive thrus. My grandfather and i, last night, tried replacing the thermostat, thinking that might help. Nope, it didnt. So then we replace the lil Coolant Temperature Sensor housed on top of the area where we replaced the thermostat. And yet again, That didnt help. We think its electrical, because when I have the A/C on in the car, the fan on the radiator comes on for 3 seconds and then turns right back off. it will keep doing that until I turn the A/C off. the fan however doesnt come on at all, or at least not yesterday, when the A/C is off. So, all that being said, does anyone have a clue as what else could be the problem? I would really, really, appreciate the help. Let me know if ya need any additional info from me. Thanks in advance. -Drewski  

First of all there ia a website --autozone.com
It has free online repair advice for many makes and models.

Now as to the overheating. Most probably the thermostat you replaced is for the dashboard guage/ or idiot lite--i dont know which one is on your car.
A lot of these year cars also have another thermostat sensor to operate the electric fan.
Thefan is running so my first guess is that there is a sensor that is kaput.  

I had some time to kill so I did some further checking on your vehicle.

There s only one temp sensor for the car as far as I can see. However there is a Relay to operate the fan. It is located under the hood,on the drivers side, mounted in the relay block.
These relays do have a habit of wearing out and maybe thats why your fan runs on and off.  

On that 2.0 DOHC, there are two sensors located on the thermostat housing, the top one is the coolant temp sensor,  a double pole part number ECH TS4060, this one measures engine coolant temp used by the PCM to determine cooling fan and A/C operation. On the bottom is the Temperature indicator sending unit a double spade connection for the temp gauge. You should have a gauge instead of a light. Part number ECH TS6696.

Which one did you change??  

I stand corrected JGate. I thought there were two but I just didn't see'em. And when I tried another way I guess I just typed the wrong terminology.  

hey everyone thanks for the replies!
ok Jgate, Yeah i knew about the 2 sensors on the thermostat housing. I replaced the top one, that controls the cooling fan and a/c.

Funsalo, i did look at the relay, but i wasnt quite sure of which relay at that time was the one for the fan. i will double check that tomorrow however. i think i over looked it, cause im not the best at cars as i am with computers. but ill def replace it, just incase.

ill be back with more info on my side. n e more idea, id be delighted to hear from anyone. thanks again! -Drewski  

On that 95 there are two relays for the fan ,  a low speed and a high speed relay,  located in the power distribution box in the engine compartment.  The high speed relay should be the 1st relay from the front toward the fender inner panel side.(black)  The low speed rely is the next one to it on your right,(dark green).   You will have a fan resistor in this circuit just behind the grill.  

hmm interesting, yeah i just checked it out. how can i tell if they are blown?  i cannot see inside them.  

and what bout the fan resistor?  

You really don't have to check the relays, you can check for voltage on the battery side and on the "switch" side on the relay terminal in the box, use a LED test probe or a DMM, I like to use a POWER PROBE, really a must for easy and safe diagnosis of today's cars and trucks since they have all have the ECM It doesn't let the voltage pass through like a regular test LIGHT,, If you don't have a LED test probe or a DMM, you could buy just one new relay and switch them out one at a time , aftermarket relay should only be 8 or 9 dollars. Another way is to start the car and listen for a click when the temp gets high enough to kick on the fan,or feel for the click. I really don't know how involved you are with electronic diagnosis, so I won't have you jump the circuit. Unless you fell confident enough.  

yeah i dont have any of those devices. i am decent with electronics.
i do hear the click when the fan turns on for like 3 secs, which btw sounds like its jumping right into HIGH mode. then it clicks again and turns right back off. this is repeatedly done when the car is over the norm temp level.
that help ya with n e thing??  

Well the relay could be clicking off for a few reasons, loss of power from the temp sensor, short in harness, bad relay, bad motor over heating the relay,  bad fan resistor overheating. That is why you need to take voltage readings from the switch terminal at the PDC, to see if you are still recieving the "relay on" command from the temp sensor when the fan kicks off.  

well imma try n replace both relays. itll be easier for me. but its gonna have to wait till this coming friday when i get paid. i really hope its just one of those and nothing to more complex. ill be back shortly with results..

everyone have a merry christmas! thanks for the help!  

If cooling fans are not coming on at all then it would overheat all the time not just sitting still.If you shift to neutral at red light or stop sign and rev up does the needle go down?Slim chance both relays would be bad.Do you have a dc voltmeter?Could do some voltage checks.