Cooling Fans

[JRNY13]

Without the AC running, about what temperature should I expect the cooling fans to kick on? Is one fan dedicated to cooling and the other for AC, or would they either both be on or both be off?

[David T]

Without the AC running, about what temperature should I expect the cooling fans to kick on? Is one fan dedicated to cooling and the other for AC, or would they either both be on or both be off?

Both fans are switched on and off together unless you have a fancy controller like a Fanzilla which sequences them so they don't both start at the same exact time. Depending on the Otterstadt switch the fans should come on somewhere near the first tick mark on your temp gauge. Or when you turn on your A/C

[JRNY13]

The temp gauge was halfway between the first tick mark and the 220 mark and they hadn't come on. As soon as I switched on the AC they came on however. A quick look at the SpecialT website says the stock otterstat turns them on at 207F.

[DMC5180]

The temp gauge was halfway between the first tick mark and the 220 mark and they hadn't come on. As soon as I switched on the AC they came on however. A quick look at the SpecialT website says the stock otterstat turns them on at 207F.

The gauge is not a 100% accurate representation. They will very slightly.
I've used 3 different otter stats in 21 years.
They all turned ON at the 220 mark and OFF at half way between the middle mark and 220.

[Bitsyncmaster]

Mine kick on just a little above the first mark. I've seen a few other cars that do the same. That is just a little later than when the thermostat opens. You can tell when the thermostat opens by feeling the hose on the drivers side of the car will suddenly get hot.

[andy blackmon]

Both of my fans will kick on at 180. I live in Al and as everyone knows summers here are very hot.My car never reaches the 200 either running hard or at a long idle. I guess my fans are really good or my gauge is off. Either way after 33 years of ownership I have never had a cooling issue with my car. A few years ago I upgraded my fans not because of a cooling problem but to reduce the electrical draw. I would say my Delorean is and has been a great car except for the crappy electric system it came with. Thank to all the folks on this forum and our vendors all of these issue seems to be solved. Andy B

[pk2678]

Because of a cooling issue, I just had to change my thermostat and later on decided to change the otterstat too.
The old thermostat opened at 75C/167F. The new one at 87C/188F. The new one opens at higher temperature to allow the engine to get warm more quickly.
Now when driving on the highway the temperature was just above the unlabeled mark between 100 and 220, without cooling fans running. Sometimes I noticed, that after a short speed-up, the cooling fans started, but did not get switched off again. The temperature was still slightly above the unlabeled mark. And did not get below the temperature where the otterstat should switch off the fans. When driving at 80 mph, I believe it makes no difference to cooling if the fans are running or not. And if it makes no difference, it is better to have them not running all the time.
So I replaced the otterstat with another one which starts the fans at slightly higher temperatures. The old one had the range 92C/197F (on) to 87C/188F (off). The new one has a range 97C/206F (on) to 92C/197F (off).
Now the fans are starting when the temperature is about half the way between the unlabeled mark and 220. This should be 97C/206F. And they are switched off just above the unlabeled mark. This should be 92C/197F. And when driving on the high way at 88mph (sometimes I drive faster, but nothing special happens), no fans are running anymore.


The temp gauge was halfway between the first tick mark and the 220 mark and they hadn't come on. As soon as I switched on the AC they came on however. A quick look at the SpecialT website says the stock otterstat turns them on at 207F.

Did the fans come on without turning on the AC? If not, check if the connections to the otterstat are ok. If a connector has come off, the otterstat would never switch on the fans. You can also try to let the temperature go up to 220 to see if the fans come on. The PRV-V6 is a tough engine and 220F is still acceptable.

--Peter

[DMC5180]

Nice write up Peter. This is something that tends to be overlooked. The otterstat should always be at an operating range above the thermostat. I run a 192F thermostat. Normal A/C off driving at speed puts the temp needle one width above the middle mark. My otterstat cycling occurs ON at 220 or just below and off is at halfway between the marks. About one needle above the normal operating spot.

[JRNY13]

Because of a cooling issue, I just had to change my thermostat and later on decided to change the otterstat too.
The old thermostat opened at 75C/167F. The new one at 87C/188F. The new one opens at higher temperature to allow the engine to get warm more quickly.
Now when driving on the highway the temperature was just above the unlabeled mark between 100 and 220, without cooling fans running. Sometimes I noticed, that after a short speed-up, the cooling fans started, but did not get switched off again. The temperature was still slightly above the unlabeled mark. And did not get below the temperature where the otterstat should switch off the fans. When driving at 80 mph, I believe it makes no difference to cooling if the fans are running or not. And if it makes no difference, it is better to have them not running all the time.
So I replaced the otterstat with another one which starts the fans at slightly higher temperatures. The old one had the range 92C/197F (on) to 87C/188F (off). The new one has a range 97C/206F (on) to 92C/197F (off).
Now the fans are starting when the temperature is about half the way between the unlabeled mark and 220. This should be 97C/206F. And they are switched off just above the unlabeled mark. This should be 92C/197F. And when driving on the high way at 88mph (sometimes I drive faster, but nothing special happens), no fans are running anymore.



Did the fans come on without turning on the AC? If not, check if the connections to the otterstat are ok. If a connector has come off, the otterstat would never switch on the fans. You can also try to let the temperature go up to 220 to see if the fans come on. The PRV-V6 is a tough engine and 220F is still acceptable.

--Peter

The fans didn't come on without the AC, but I may not have let it get warm enough yet. I turned the engine off at that point. In normal driving situations, my temp gauge has never been anywhere near 220.

[iflights]

Reserrecting a relevant thread...

My car came from PO with the Fan Fail socket bypassed to run the fans all the time. Pulled out all that ghetto stuff, and replaced with Dave's Fan Fail module. Fan Fail testing works as designed, pull both fuses from module, get double blink on fan fail indicator, and no fans running. Put 1 fuse back into module, get single blink, + only 1 fan running. All as you would expect.

However, both fans start up as soon as I start the car cold. I'm thinking the only realistic possibility would be a bad otterstat at this point.

Any advice?

Thanks in advance.

[DMCMW Dave]

Reserrecting a relevant thread...

My car came from PO with the Fan Fail socket bypassed to run the fans all the time. Pulled out all that ghetto stuff, and replaced with Dave's Fan Fail module. Fan Fail testing works as designed, pull both fuses from module, get double blink on fan fail indicator, and no fans running. Put 1 fuse back into module, get single blink, + only 1 fan running. All as you would expect.

However, both fans start up as soon as I start the car cold. I'm thinking the only realistic possibility would be a bad otterstat at this point. .

A bad otterstat or the same Prior Owner put a jumper somewhere in the system. Those can be fun to find.

Unplug the otterstat and see if the fans turn off. If they stop, it's bad. If not, unplug the top left (yellow) bulkhead connector and see if they shut off. Do this with the key on/engine off, the yellow connector will kill the engine anyway since it also carries the ignition.

That will tell you if the mystery jumper is inside the car or on the engine.

[iflights]

A bad otterstat or the same Prior Owner put a jumper somewhere in the system. Those can be fun to find.

Unplug the otterstat and see if the fans turn off. If they stop, it's bad. If not, unplug the top left (yellow) bulkhead connector and see if they shut off. Do this with the key on/engine off, the yellow connector will kill the engine anyway since it also carries the ignition.

That will tell you if the mystery jumper is inside the car or on the engine.

Found it, thanks Dave! Bad Otterstat, fans don't run now. Based on its position, I'll add this to my list of winter work with DMCMW.