Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Valentin]

Hi guys, I found out, with the high temperatures of the last few days, my collant fan doesn't engage in low speed. When I put AC on, it should run at low speed, but it doesn't.
It only engages when temp gauge reaches just before 105, AC on or off.

I tested the 3 wires connector of the thermoswitch under the top coolant hose, with ignition on ,1(gnd) with 2 = a fan under the relay box which I don't know what it is. 1 with 3 = full speed on coolant fan.
Nothing activate the low speed on coolant fan. What thermoswitch engage the low speed for this fan? And which relay on the box? I read few times the topic of test relays, but I can't understand clearly.
I only understand there is a resistor somewhere that drives the low speed, and I cannot understand which element activates the low speed.

If I put the AC on, the 1st AC fan switches on. When I reach 105°C, the second AC fan switches on at the same time as the collant fan full speed.

I can drive the car but on mountain roads or above 30°C outside, the car cannot regulate and reaches 105°C in only a few seconds when I slow down. The full speed fans do a great job by decreasing the temp very quick to 97,5°C but I don't want to drive like this too much time.

And I'm 1000km away from the house of course 

[TheBoy]

Try https://www.omegaowners.com/forum/index.php?topic=133825.msg1716189#msg1716189

[Valentin]

Thanks TB, but it's is precisely this document I cannot manage to understand. It is really not clear the way it's explained. What am I supposed to do with the test connector? I need to buy an adjustable switch to emulate the temperature? Or I can activate the different fans by connecting ground to each FT? Because in this case, I already tested at the primary thermoswitch P1+P2= activates a fan somewhere behind de relay box, but none of the ones attached to the radiators. P1+P3= activates the main fan attached at the back of the collant radiator at full speed.
Is P1+P2 supposed to activate main fan low speed?

From this, do you agree that the issue seems to be between the relay and the fan itself? I can hear the relay clicking when connecting P1+P2.

[TheBoy]

I believe its just shorting certain pins, but not 100% sure.

In your case, I'd identify which relay is clicking, and then investigate if you can short out relay to eliminate that?

If you have a wiring diagram, such as in the Haynes book, you'll see its quite a complex circuit, and I think you'd need to refer to it to diagnose further. 

[Valentin]

After investigation on the car and the help of this : https://oldsite.omegaowners.com/forum/YaBB.pl?num=1277831253/2#2

I found it was fuse 52 (position 8b in the relay box in the engine bay, 30 amps) that was shot. I replaced and tested the fan again at the top thermoswitch connector, works fine. But now I need to understand why it blown, and prepare a stock of fuses for the return journey

[Doctor Gollum]

Possible that one or more fan motors is starting to seize.

The front ones can be removed without dismantling anything iirc.

Check they spin freely. Engine cold obviously...fingers work better attached.

[Valentin]

Oooooh DG I just had a flashback!!!!!!! Thanks!!!!

Actually, Friday evening, after refill of the AC circuit, the auxiliary fan n°2 which was running full speed was making some noise after engine shut down, like clac clac clac at the very end of the running cycle. Then I removed the bumper to see where the blades were touching something. And they were touching the Y fitting for the windshield/headlights washer as it was positioned horizontally. I turned the Y fitting to vertical position so it doesn't touch the blades anymore and I didn't pay attention further more because the fan was running, and if it runs, at this moment in my mind I don't know there are 2 levels of speed on this one. I guess it forced against the blades and as the AC was empty for a year I didn't have the possibility to find out there could be an issue. Because this aux fan n°2 only comes ON at low speed when the AC is ON. Running at low speed probably had no enough inertia compared to full speed.

Everything's clear now : all started because that Y fitting was touching the blades, I never really had a working AC = I never had the possibility to encounter this situation.

Hope that could help others in diags

I will update this topic when I come home after another 1250km journey, to be sure there is no other issue

[Valentin]

Can anyone explain to me what is the "blower motor" ? It is on the line 768 activated by relay K48 (first stage 100°C thermoswitch or AC pressure switch 275psi).

I can hear it somewhere underneath the relay/fuse box in the engine bay, but I don't understand its purpose

[Doctor Gollum]

Early cars had a small fan behind the left front wing on the A pillar structure to blow air into the fuse/ECU box to cool it.

Later models did away with it.

[Valentin]

Thanks for the clear explanation