electric fan install question

ericbphoto · Aug 25, 2016

Hey, Y'all.

I did the VOLVO electric fan install as described in the tech articles and I have a question. I used the volvo harness and relays, the BMW dual temperature switch (brand new from rock auto) and a separate "enable" relay and fuse with cutout switch on the dash. Just like the diagram in the tech article.

Background - 93, 3.0l, 4x4

When I got done, engine cold, I turned the switch on and the fan started running. Was this supposed to happen? I was thinking the fan should not run until the coolant temperature got to the first switch setpoint for low speed. Is that how it works? or does the bmw switch just toggle between high and low speed?

I didn't get to troubleshoot yet. Went to bury the neighbor's dog for him and my Case "general purpose pipe and cable locator" (ie; backhoe) located a few things that took the rest of the day to repair.

RonD · Aug 25, 2016

From the drawing on that page the switch in the dash will just close the power relay for the Volvo relay set, switch is just to shut off fan, not to start it.

So no, the fan shouldn't run until thermostat opens and warm coolant is circulated thru the upper rad hose, assuming that's where temp sensor is installed.

Just a heads up, this temp sensor needs to be mounted side ways or pointed down, so it is always covered by coolant in the hose, upper rad hose is where air collects.
This isn't your problem

The temp sensor unGROUNDS the Volvo relay, thats how the system works, when coolant temp gets to minimum temp then #1 is ungrounded then low speed wire to fan gets power.
When hot enough #2 gets ungrounded and High speed wire gets power.
So I think you may have the sensor mis-wired or Volvo relay has a stuck relay inside

When #1 and #2 are grounded fan should be off, so if sensor ground is not hooked up then fan would be on all the time.

ericbphoto · Aug 26, 2016

Thanks, Ron. I thought the temperature switch is actually Grounding the coils in the volvo relay package. I will have to check the switch with a meter and see what's really going on.

The problem is that I had to assemble the harness plug for the temperature switch. I first did it as shown in the picture in the tech article, with the ground (green w/black stripe) in the center position. The instructions are unclear about which terminal is which on the temperature switch. The fan first came on in high speed. So I swapped 2 wires and it came on slow. That's as far as I went. I just figured the switch was meant to toggle between high and low, with one of them always on.

If what you are saying is true, that the temperature switch contacts are normally closed and then open at temperature, then having the wires wrong at that switch would do what I am seeing. I won't get to play with it again until monday.

Yes, I do have the temperature switch horizontally mounted.

(don't laugh at my intake plenum. That's a work in progress.)

ericbphoto · Aug 30, 2016

I checked the bmw dual temperature switch and it is definitely conducting through one set of contacts at ambient temperature. This is contrary to any drawings I have found regarding the way it is supposed to function.

I also found that the volvo relay package I got with my junkyard fan is flaky. I can bump it and turn it off while the fan is running.

I will order a new BMW temp switch to verify it's function and replace the relay package with either a new volvo replacement or separate generic relays.

ericbphoto · Sep 2, 2016

Got it working today. The first temperature switch I ordered was bad.

I designed my own relay circuit for it. Drawings to be posted next week.

My circuit uses 4 relays;
1 master cutoff relay
2 slow speed relay
3 fast speed relay
4 relay to make sure fan runs when A/C compressor is running.

RonD · Sep 2, 2016

Sound interesting, Good Work :icon_thumby:

ericbphoto · Sep 5, 2016

Here is the wiring diagram I mentioned. It is functioning fine in my truck. My fan is installed on a sheet of plexiglass right now, But I will replace that with Lexan which is stronger and less brittle, so it should withstand bumps and vibrations better.

3 of the relays are bolted to the top of the fan support. The main cutoff relay (R1) is in the underhood fuse/relay box. That took a bit of work, but I like the result. I repurposed the Power door locks fuse as a fuse for this since it was already wired.

JoshT · Sep 6, 2016

Interesting, I'll be watching this. Will probably be doing a 2 speed fan on one or both of my Rangers.

Got to refresh myself on relay wiring so I'll know what you are doing with the blue wires in the middle, but I assume it's to keep both relays from going active at the same time?

Looks like you've got the fast and slow sides of the BMW Temp Switch swapped and run to the wrong relay. May be wrong about that though.

The master override off switch is a good idea especially if you plan to play in deep water and mud.

Mark_88 · Sep 6, 2016

Nice...but I must ask...is that plexiglass you mounted the fan on or aluminum?

Either one will work...but I thought aluminum would be a better material for that application...aside from the fact that plexiglass prices are ridiculous. A sheet that size in Canada can run you $50 to $75...at least the last time I priced it...

ericbphoto · Sep 6, 2016

Josh,
Yes, the blue wired are the electrical interlock to prevent energizing both speeds simultaneously.

Mark,
I think this is plexiglass. It is what I had on hand and is temporary. I think plexiglass is too brittle, so I will soon replace it with Lexan or aluminum.

Mark_88 · Sep 9, 2016

ericbphoto said:
Mark,
I think this is plexiglass. It is what I had on hand and is temporary. I think plexiglass is too brittle, so I will soon replace it with Lexan or aluminum.

that's what I would be concerned with. Although not fragile under normal use, the heat and possible cold/heat exposure would likely cause it to fail.

Road signs are typically aluminum if you can find an old one that has not been sent for recycling. I found a large construction sign on the side of the road once that must have blown off the back of a road crew truck. It would be an almost perfect fit for the rad opening...maybe a bit of trimming needed.

ericbphoto · Sep 9, 2016

I thought roadsigns were free between midnight and 4:00am?!?
:shok:

RonD · Sep 9, 2016

ericbphoto said:
I thought roadsigns were free between midnight and 4:00am?!?

40 years ago a friend had a bit too much "chemical enhancement" i.e. alcohol and pot.
He decided that hunters would have an unfair advantage in using the Deer Xing signs on the highway.
They could sit and wait for the deer to cross there and shoot them.................

So he went out in his Dodge Power Wagon and proceeded to knock all the Deer Xing signs down, and so hunters wouldn't know where they were he loaded each into the back of the truck......................
He started at about miidnight

He had 12 Deer Xing signs in the back of the truck when he was pulled over, about 6am.
So I don't think road signs are free between 12:00 and 4:00am,

Mark_88 · Sep 9, 2016

LOL...after I posted that I realized that there might be a sharp increase in missing road signs...but I am not endorsing this as either a legal activity or that you should obtain specifically a road sign for your e-fan mod...

I would suggest going to a road crew station and ask nicely if they could tell you where to buy the material or if they happened to have any old ones that they were not going to use again.

Since these are typically government run operations there is a good chance that they would not be allowed to sell you anything....but better to ask...

electric fan install question

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