So, really pulling my hair out on this one. I have Alldata and I also have the factory service manual on this 1993 626 2.5L which happens to be my own vehicle. The problem is that both the cooling fan and condensor fan come on at full speed as soon as (I'm assuming, since the conditions seems accurate but I lack a Mazda SST for monitoring on this vehicle) it enters closed loop. For the remainder of any restarts as long as the vehicle is warm enough for it to be in closed loop, the fans will come on and run as soon as the vehicle is started.

I've checked every fuse in the engine compartment and in the side of the dash. All are good.

I've tested, and then replaced just to be sure, all three of the relays for the cooling fan and all of the relays related to the AC system, which by the way, has been deleted from the vehicle. Before saying that this is the problem, you have to know that the AC was deleted entirely about two years prior to the start of this problem, so it's not because of the disconnected electronics related to the AC system. It worked fine after doing that for two years and only started this problem a few months ago.

I've also replaced all three coolant temp sensors, since there are two of them near the thermostat housing plus another for the gauge. Two of them are two wire and one of them is a single wire, for the gauge. Honestly I don't understand fully why there are two CTS as every bit of documentation and every forum or video I've been able to reference only indicates one CTS plus one sensor for the gauge on all 93-97 626 although it seems I recall DJDevon3 from the old mazda626.net forum, or maybe Snailman, mention something about some models have multiple CTS quite a while back. Anyhow, all three are new.

I've retuned the TPS sensor in diagnostic mode to be sure it isn't a misadjusted TPS contributing to the problem, using the fan method. Had no effect either.

I'm kind of down to thinking it almost has to be a PCM problem but I'd really like to get some fresh insights before even thinking about going down that road as maybe there's something I'm missing or have overlooked. I'm not seeing any wiring issues that are obvious and clearly the wiring between ignition switch and PCM and PCM and ground are good, as both fans DO function, although only it seems at high speed. Seems like a default behavior like you'd see if the PCM was lacking a required feedback but everything other than the AC SHOULD be accounted for. Even if I completely disconnect the condenser fan for the AC by unplugging it, and unplug the AC relay, and all three condenser fan relays, the cooling fan relay still has the same behavior.

If anybody has some actual insights on this or things I may have overlooked on this specific 2.5L cooling fan system, I'd greatly appreciate hearing it. Thanks.

 

Still looking for insights on this if anybody has any, as I've still not been able to resolve it yet.