auxiliary fans not turning on 190e

[downeywu]

i have noticed my auxiliary fans will not turn on when engine temp goes up, or when i turn on the A/C... another thing i noticed is when i start my car the fans actually get a slight burst of power and spin for a little bit

my question is are the fans being shorted out by bad wiring? i really would like to figure this out before summer got here

[Arthur Dalton]

With key On , pull connector off 2 wire blu sensor..have high fan ??

Jumper pigtail wires at reciever dryer pressure switch...have Low fan ???

[downeywu]

i have done the one test with the connector on top of the engine and the fans turn on high...but i havent done the other test yet after i do that one what do i look for next?

[Arthur Dalton]

< __________________

That depends on the Results of that test,. of course.........
Would you like me to send you on a goose chase?

[Lexxani]

check your relay, it should be the same as your starter and window relays, at least it is on my 107. That was the culprit as to why mine was not working when I bought her. The relays should be located near the main fuse box, if not consult the FSM.

[downeywu]

ok i did both tests, i had high fan on the one test and low fan on the other...so where do i go from there?

and also why is it when i turn my key to position #2..my fans get a very little burst of power and spin for a second?...and it seems like i hear some clicking of wires....but i could be wrong

[Arthur Dalton]

The high fan will not trigger until the coolant temp is 105C.
The low fan will not trigger until the a/c systems high side pressure detects a high thermal load.

Are either conditions being met//

You may have a poor connector at the blu 2 wire sensor or a bad sensor.
And on the a/c low fan, you may be low on refrigerant. Check eyesight.
You may also have bad insulation wire harness.
Have an ohm meter?????????

[downeywu]

yes i have an ohm meter...and my temp has definitely been above 105..because after a drive and i stop a store..go in and then come out and i start the car again and its up to like 110ish..i thought they would turn on to cool the engine?...im leaning towards bad insulation wire harness simply because they fans get a burst of power when i turn the key to 2 position

[Arthur Dalton]

Do you see flaky insulation on harness , specially near the blu temp sensor ??

When you get to 105c . pull the connector off the blu sensor and see if high fan defaults ON.
If so, get a 1K resistor from Radio Shack and put it across the unplugged connector and see if that turns the default fan back OFF.
If it meets these two criteria, then change the sensor.
If not , you have a wiring problem or a sticking relay.
When engine is cold, before you turn the key on, pull the connector off blu sensor and take an ohm reading across the sensor and post the results..

[downeywu]

i havent been able to get the car above 105 because it is still too cold out...i dont visibly see any flaking on the wires..i took 2 readings just incase it made a difference...

12.05 with the ohm meter at 20k (connector off)
.807 with the ohm meter at 2k (connector on)

i was able to check it with the connector on because the clip is broken that holds the 2 wires in place on the sensor

would a bad sensor make my fans spin for a split second just before starting the car?

btw thanks for your help so far i really appreciate it!!

[Arthur Dalton]

I just asked for temp sensor ohm values.

So, here is the specs value temp/ohm chart for that sensor and you can see if yours passes the specs.

20C- 5K-8K ohm
60C- 900-1800 ohm
85C- 460-650 ohm
100C- 300-400 ohm

I would test both 20C and 100C and that will tell you if your thermistor is relating to temps correctly.

I don't know why you are giving me readings with the connector on , as that gives incorrect sensor values b/c you are measuring the circuit, not the sensor. We are attempting to measure ONLY the sensors ohms value. And when you get that , compare it to the spec. chart and then you will know if you have an open /shorted/calibrated sensor or not...

[downeywu]

ok sorry about that...i'll post the results up shortly thanks again

[downeywu]

ok i couldnt tell exactly what the temperature was at but i came up with these results
80c 585 ohm
60c 771 ohm
45-50c 1.533 ohm
35-40 2.15 ohm
30-35 2.85 ohm

i cant get the car up to 100C because its too cool outside still..

something i did notice though when i took out 2 relays...my fans still did that slight burst of power thing when i turn the key...and then with the relays out i tried touching the 2 wires on the sensor together and the fans wouldnt come on...does that mean i have a shorted wire?

[Arthur Dalton]

Your ohm values look OK , a long as I assume you really mean K ohms on the higher readings. [ 2.15/2.85 ohm....those HAVE to be K ohms]]

If the fans come on with the key ON and relays pulled , you have a short on the R15 resistor feed somewhere.

OI also assume you see the fan come on with the key ON before the car is started.

[downeywu]

yes they turn on for a split second before the car is started....and yes thats also k ohms...so i guess im down to a short on the R15 resistor...where is that located?