ludeowner

Hi guys,

Just recently I noticed that my temps seemed to be about 10-15 degrees F higher then normal. I noticed a few things about how my radiator fans worked when I picked the car up a few months ago.

Since I got it I always drive around with my parking lights on since I hear that helps with the fans coming on earlier. One of the things I also learned aboutthe car was that you could control the rad fan speed with the fan control in the cab. On hot days I would run the fan speed on 4 and on cooler days I left it on 2 or 3.

Noew the thing that I am unsure of is, does my AC have to be turned on for this to work? I am asking this because I noticed that my fans would work even if my AC was off. So I had thought that it made no difference if the AC is on or off. But when I noticed my temps rising, I started to check out my cooling system. I saw that my fans no longer turn when the AC is turned off. however the fans did turn when my AC was switched on.

One other thing that I noticed was my AC compressor pulley (the one beneath the PS pulley). I saw that the inner part of the pulley stops when the AC is off, and of course when the AC is on it will turn. The outer part of the pulley will turn regardless of whether the AC is on or off. Now I mention the AC pulley, because I could have sworn that the pulley used to turn all the time (even when my AC was off).

And lastly one other thing that I have noticed is the fans staying on after I shut the car down. Before the fans would stay on almost all the time with the installation of my M2 ECU. However now the fans will not come on when I shut down.

So based on my observations what would you say my problem is? or is this the same type of behavior you guys see with your FDs? I have not yet checked my fan relays. I just gave the mechanical parts a quick look and checked all fuses, to include the AC fuse, to make sure they weren't blown. My front underpanel also is falling apart, but that still doesn't explain why my fans are acting up now.

Anyways, any input you guys have would be appreciated.

TIA

es

There is an electrical load over-ride as well as an AC Load over-ride. The AC over-ride will kick the fans on at a lower temp then the EL.

ludeowner

How is that relevant to my fan problems? before I could control the fan speed with the Air Conditioner off (irregardless of water temps). Now in order for me to control the fans speed I have to have the AC on.

Kento

My rad fans never worked by controlling them by the cabin fan "irregardless of water temps." Even after I switched to a Pettit ECU. The only time the cabin fan **** would have any effect was if the coolant temps were already hot enough to activate low speed on the rad fans. Definitely easier to activate them with the AC.

Not sure why your "10 minute shutdown sequence" is seemingly on the fritz. Although I have encountered some weird behavior from my ECU at times (alarm once activated by itself several years ago, but hasn't done it since).

adam c

iTrader: (2)

First of all, I have a 94 FD. I believe that the fans work the same from 93-95. If that is wrong, please disregard this post.

I don't think the fans are controlled, in any manner, by the interior fans without the AC on. With the AC on, the fans come on too. Regarding the parking lights, yes, that will trigger the fans to come on a little earlier. I don't know exactly how much earlier. Driving with the parking lights on will make you look even more like a Vette. That's a bad thing!

I suggest that you check your fan relays to make sure that they are both coming on. If only one is working, that could be your problem. If you have not done the "fan mod", You should try it. It's easy to do, and easy to undo if you want to remove it.

http://www.scuderiaciriani.com/rx7/fan_mod.html

ludeowner

When I first looked at my radiator fans after discovering my problem I saw that the passenger side fan was stopped, but the driver side was spinning. The AC was off at the time. A few minutes later I saw that both of the fans would not spin with the AC off.

I had read on the Scuderia site a while back that the radiator fan speeds could be controlled by changing the tempurature control in the cab. However I noticed that I could do it with the AC off. It seems that everybody on the web says that the AC has to be on though for this to work.

About the fan mod, I didn't think I needed to do it since my fans would come on anyways. However I think I may have to check my fan relays to se if anything is wrong there.

karken29

I have a 93 FD. Regarding the Radiator fan operation... If you pull the passenger side panel, where you ECU is located, there should be a small black fan-relay box. It use to be bolted to the back side of your stock ECU....

Anyway... You can bridge in a manual switch into that fan circut so you can control their operation as needed.

As for the Airconditioner... I know that turning on the airconditioner will cause the fans to also operate... which is how mine is set up..

I believe that running your parking lights all the time places sufficient load on the engine via the altanator, to also cause the cooling fans to run... at least according to my son "goodfellafd3s" it is. I'm not sure about that though...

Another thing you should check out is the radiator cap on your AST (if you still have one) tank. If this cap is going bad, you engine will run hotter... btw you'll need a 13lb. cap, "Unvented" if you do replace it.

Let us know if that helps and how you make you...

I don't think you mentioned it, but do you have an accurate temp guage... other than the reading your seeing from your ECU hand-held ...?

If not... you may want to consider one.

GooRoo

iTrader: (4)

I had a similar problem recently with wierd fan behavior, and I went with the 'what's easiest to check' root cause finding method.

First up was the fuse, in the main fusebox and lo and behold it was dead. However after I replaced it seemed that the fans were working but week later they were acting wierd again.

Next up was the fan relays near the front passenger side. They are easily tested with a 12v battery and a Multimeter. All in my case were fine, however the wiring looked really bad so I rewired them all.

I should say somewhere in the middle here someone suggested that I check the thermostat, so I replaced that as well. There theory went that if the thermostat never opened that the fluid never goes to the radiator or hits the thermoswitch to kick on the fans. I'm not sure if this is true, but it can't hurt to replace the thermostat.

Still no dice, so I moved to the fans themselves. I hard-wired them to test the battery and one spun but one did not. After a bit of wiring diagram reading I ordered a new fan motor, which worked fine when hard-wired. I replaced the one that didn't spin and found it was pretty much 100% siezed. Replaced the fuse and all has been good since.

The next thing I would have checked was the continuity of the wiring going to the fans from the battery etc and the wiring from the relays to the ecu.

That's how I'd check out your problem, but I'm still a newbie around here.

Oh yeah, I can verify that when you turn on the A/C the fans should go on, regardless of how high you have the fan on (as long as it's on.) Also the fans should only stay on after you turn the car off with a 3 minute high temp condition. One of the fan mods essentially tells the ECU this is the case all the time so the fans always stay on for 10 min. Anyway, if they did this without the fan mod there probably was a problem or it's just really hot and you were driving really hard.

Also if you don't have the wiring diagram I suggest you pick it up and check it out. It's not the most easy thing to figure out but once you get into it there's much to be learned. (It's available here.)

Someone please correct me if I've said anything incorrect.

spurvo

This is a little long...

According to the manual, the electrical load sensing circuit (a little box in the ECU area) will turn the fans on to low IF the temp reaches 210F AND one or more of the following is true: The rear window defrost is on, the parking lights are on (of course, this includes the headlights, as the parking lights are on at that time as well), or the heater blower fan is set to three or four. If none of these conditions is true, the fans will turn on low at 221F via the ECU which received temp signal from the green connector sensor on the backside of the filler neck. IF the A/C button is on AND the cabin blower fan is turned on (one through four), THEN the fans will be kicked to one speed higher than they are running at prior to activation of the A/C system. If the fans aren't onwhen you turn on the A/C AND the blower fan they will get turned on to low, if they are already on low they will turn to medium, and if they are already on medium, they will turn to high (you are in a world of **** by then!). I have tested all this with my 93 Touring, and it works exactly as described. Note that there is one more independent fan control circuit, which is the thermoswitch located UNDER the green connector on the backside of the filler neck. The stock thermoswitch switching temp is 226F I believe. So if your engine was running 228F and you had your A/C on for some unbeleivable reason, then the fans would be screaming at high.

Lastly, there is a recall for the cooling system on the 93's that was incorporated into the 94's and 95's. On the 93's, it's a little black box attached tot he backside of the ECU, and has a black wire with spade connector that can be traced back to it. Here, the fans are kept on for ten minutes after shutoff IF the the thermoswitch was switched for two full minutes before shutdown. This was a weak attempt to cool the engine after hot shutdown to lower the risk of either the coolant that has leaked down the backside of the upper turbo coolant line form a shitty clamp catching on fire, or to keep the fuel system from being so overpressurized against equally shitty clamps that it catches on fire. Curious they didn't update the FPD.

That's all I know, except the fan mod rocks. I chose the Dysney mod, rather than the ten minute version. SOOOO happy

2-Rotor

The ultimate lazy and cheapest fan mod courtesy of RonKMiller (have to give the guy credit from a past thread he posted stating this) is to disconnect the wire that goes to the heat filiments where it attaches to the glass creating an open circuit. This open circut will now be on an already dedicated switch (your rear defroster switch) and you wont have to splice any wires or add switches if you dont want to. Thanks again Ron

ludeowner

Thanks for all the replies guys.

2-rotor, something you said about the defroster made me think. Would unhooking the grounding wire on my antenna motor have any effect on my problem?

A few days ago my antenna motor went haywire and would not stop running. In order to keep the motor from burning itself out or causing damage to something else, I disconnected the grounding wire that runs from the motor to the chassis.

I will try hooking that grounding cable back up and see if that somehow fixes my problem. If it doesn't then I will try all the other stuff everybody else suggested.

potatochobit

iTrader: (1)

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2-Rotor

I wouldnt think so. I dont think the antenna and the rear defroster use the same ground. I will look into it.

ludeowner

You're probably right about them not sharing the same ground. But I was thinking that undoing the ground for the antenna motor had the same effect as unhooking the defroster. Except I dont have any way to switch my fans off/on.