Damaged somewhere in otterstat wire.

[TTait]

My otterstat is not working turning on my cooling fans. I jumped the two wires together assuming it was a failed sensor, but nothing...

I have +12 to the otterstat via fuse #5, and I checked the wiring on the brown/orange wire at the bulkhead connector, and its fine to that point.

When I turn on the AC, the fans come on properly.

I have concluded then that there is either damage in the brown/orange wire inside the car somewhere between the bulkhead connector and where the pink wire from the compressor splices in.

Can anyone tell me where in the wiring harness that splice is? I've spent a fair amount of time looking and can't find the damage, but I have a proposed workaround.

(Here is where I'm lazy, easier at this point to work around than find the problem and try to repair it in all that tight wiring harness)

I am prepared to jump from the brown orange wire at the switched side of the otterstat to the pink wire for the compressor. I have a small diode to prevent the compressor from kicking on when the otterstat switch closes. Basically I'm just reworking the splice to a point further up the pink wire.

Where I'm unsure is that there is also a diode on the pink wire that prevents the AC circuit from backfeeding the otterstat. I think this is so that if fuse #5 blows that the compressor circuit does not backfeed the interior lighting system via the otterstat.

(Here is where I'm especially lazy). Bottom line, I only have the one Diode and want to get this done at least for now. As I see it the worst that happens is that I get a short in the interior lighting circuit and blow fuse #5. I don't notice, so I drive along, turn on my air and its fine, then as the coolant heats up the otterstat closes and the lighting system shorts out a second fuse.

I actually think this is better... If I run the car with no fuse #5 I will not have an otterstat, and I might not notice. If the fans can be switched on via either fuse #5 or fuse #10 - why not? I may not notice on a hot day if my interior lighting fails, but I sure will if the AC starts blowing hot. When the AC blows hot I immediately look at both the exterior temp (on my mirror) and the coolant temp - not having the diode could prevent me from overheating by giving me a backup and obvious fain fail indicator if fuse #5 fails.

What do you guys think?

Tom

[Farrar]

Have you tried temporarily changing the otterstat's power source from switched to constant? Might make troubleshooting a bit easier, but you may have to jump-start the car when you're through.

Farrar

[content22207]

Diode is in the relay compartment.

If you want to run a temporary otterstat circuit, just take it off from the door lock circuit breaker, run out the distributor tach grommet to the otterstat, then back through the same grommet to the fan circuit breaker.

Bill Robertson
#5939

[TTait]

The power to the otterstat is fine, no worries there. Its just the return wire somewhere between where it goes back into the cabin through the connector plugs, and the point where the pink wire splices in to it, I'm basically just moving that connection to a different place in the pink wire.

[content22207]

Are you sure you didn't just knock the diode loose fumbling around in the relay compartment? It's only held on by quick connects.

The compressor has its own diode, so it's possible to disconnect the otterstat diode yet still retain radiator fan function with A/C.

Bill Robertson
#5939

[TTait]

Maybe... I have not found it to be honest. Do the relay bases lift out to access the wiring harness below? Can you describe where in the compartment it is?

[content22207]

They're in the big bundle of wires headed for the bulkhead connectors.

Bill Robertson
#5939

[Ryan King]

They're in the big bundle of wires headed for the bulkhead connectors.

Bill Robertson
#5939

Mind helping us with a photo Bill? I am having the same problem..but maybe I didn't plug something back in after I put my engine back in my car.

[WelmoedJ]

Maybe... I have not found it to be honest. Do the relay bases lift out to access the wiring harness below? Can you describe where in the compartment it is?

The relay bases are held in place with 2 screws on each bank.
You need to remove the relay that "covers" the screw.

Mind that the otterstat (=temp controlled switch) only is powered when the IGN lock in in the ON state. If you want it to - temporarily - have constant power, run a wire from the 12V post in the engine bay to the otterstat.

Checking the Orange/Brown wire in the relay area: use the connector you mentioned previously on the GND pin of your multimeter and probe the other end of the Orange/Brown wire at IN and OUT of the circuit breaker (to also check it is OK?).

[TTait]

2686

Here it is Ryan - forward inside corner in the relay area.

Thanks Bill - it was unplugged at the diode

Welmoed - I considered that it might be cool to power it off the door lock module as Bill suggested, but being always on, the fans would stay on (like many moden cars) after the key was shut off and stay on until the otterstat cooled. With that sensor so far from the radiator the running fans would do nothing to cool that sensor anyway. If someone does need to run a temp power line as Bill Suggested earlier, its probably better to stick with a switched source. Thanks.

[WelmoedJ]

[QUOTE=TTait;8274Welmoed - I considered that it might be cool to power it off the door lock module as Bill suggested, but being always on, the fans would stay on (like many moden cars) after the key was shut off and stay on until the otterstat cooled. With that sensor so far from the radiator the running fans would do nothing to cool that sensor anyway. If someone does need to run a temp power line as Bill Suggested earlier, its probably better to stick with a switched source. Thanks.[/QUOTE]

Read my reply in Radiator fans - low amperage replacement options? thread.
I explained how I wired my electronic otterstat and how long it runs after turning IGN off.

The temp power line only has been suggested for the duration of the search for the cause of your problem.

By using the MM at various points down the wire from the firewall connector to the fan relay you may be able to pinpoint the culprit.

Hopefully it doesn't take too long to find the interruption.
Good luck.

[Ryan King]

2686

Here it is Ryan - forward inside corner in the relay area.

Thanks Bill - it was unplugged at the diode

Welmoed - I considered that it might be cool to power it off the door lock module as Bill suggested, but being always on, the fans would stay on (like many moden cars) after the key was shut off and stay on until the otterstat cooled. With that sensor so far from the radiator the running fans would do nothing to cool that sensor anyway. If someone does need to run a temp power line as Bill Suggested earlier, its probably better to stick with a switched source. Thanks.

Thank you Tom, Ill check it out! :approve:

[TTait]

I'm good now - how about you Ryan?

Thanks Guys!

Welmoed - I think you should come over and see if you approve of the work I've done recently!

[WelmoedJ]

I'm good now - how about you Ryan?

Thanks Guys!

Welmoed - I think you should come over and see if you approve of the work I've done recently!

I love to come over.
Only just to be for an approval inspection: way to much honour, I'm not at that level :)