Radiator Fans not working w AC jumpered

[Beachdrifter]

Hi all,
So radiator fans come on when otterstat reaches temperature.


In another scenario I turn mode switch to MAX and jumper the ac low pressure switch. I notice compressor clutch engage but no fans come on. I always assumed fans come on when low pressure switch activates.
I have Herveys 2x2 fan fix module. Would this mean that the module is going bad or gone bad?

It's not a complicated circuit but I find it strange that fans work via otterstat but not ac switch jumpered??


Thanks!!

[Jonathan]

Bad diode, maybe? If memory serves, there are two of them lying in the fuse/relay area behind the passenger seat that allow the fans to run with either the otterstat and/or the A/C compressor.

[DMC5180]

Check for a bad (open) diode. The diodes (2) are located in the main harness just to the right of the fuse box. The easy way to quick check this is to just unplug the diode and reconnect the wires without the diode. Your looking for the diode withe the pink wire. If the fans then work when switched to Max A/C with key ON low pressure switch jumped then you know you have a bad diode.

I had this same diode fail on my car once. It did exactly what you described, fans worked with Otterstat, A/C clutch would click but fans wouldn’t run.


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[Beachdrifter]

Thanks guys. I'll check the diodes when I have a chance and report back. I've never replaced them in my car; have no idea if they're original or not.

[Beachdrifter]

Also in the event I do have to replace my diodes. What are the specs on these? Which type?

Thanks.

[Bitsyncmaster]

Also in the event I do have to replace my diodes. What are the specs on these? Which type?

Thanks.

Pretty sure the OEM diodes are 1 amp rated. I typically would use a 3 amp diode so you have larger wire to attach to. I try to use 250 volt or greater voltage rating on automotive diodes so inductive noise does not blow them.

[Beachdrifter]

Pretty sure the OEM diodes are 1 amp rated. I typically would use a 3 amp diode so you have larger wire to attach to. I try to use 250 volt or greater voltage rating on automotive diodes so inductive noise does not blow them.

Great thanks so much Dave.

[Beachdrifter]

Hi friends,

So just a follow up. I ordered a new set of diodes and worked like a charm. Not to mention I decided to replace my ac lines with the split hoses and new condenser accumulator, plus r134 now, and system is working great. Blowing about 49 on highway speeds. Took two weekends of work but got it done.