Scorpio AC fan always on

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john keefe
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Re: Scorpio AC fan always on

Post by john keefe »

BTW, I'd love to drop a 4.6L into this car. Or, a 5.0L. Moves pretty well?
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Re: Scorpio AC fan always on

Post by john keefe »

Great call on tracing 31B-18. Turns out there was a Mickey-Mouse'd relay rigged up to that circuit and By/Y 54-37, tucked up under the driver's side headlight bucket.

It was upside down, so must have corroded from moisture over time. Unhooked four wires, problem solved.

Its before the diode. I assume whoever installed the Radido receiver/dryer rigged it up to either by-pass the diode to the A/C compressor clutch, or to make sure it activated the fan at low speed if the diode ever crapped out.

Now I have to figure out how to redo the relay. When I said Mickey-Mouse, I meant it... They used a handy 5-prong (14B192-AA) relay, jumpered two pins (87 & 86) to ground, and left the center 87a pin bare. So, now gotta' figure out why that arrangement worked, and how that applies to a standard 4-pin relay.
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Re: Scorpio AC fan always on

Post by Ed Lijewski »

Anyone else thinking what you found was the "fix" re the TSB?

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Re: Scorpio AC fan always on

Post by john keefe »

Could be. But, this one was definitely done by an amateur.
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Re: Scorpio AC fan always on

Post by Ed Lijewski »

Can anyone find the M57 tech sheet?

"NOTE: VEHICLES BUILT BEFORE DECEMBER, 1987. OWNER NOTIFICATION PROGRAM (M-57) RELEASED A MODIFICATION TO THE CONDENSER COOLING FAN SYSTEM FOR ALL VEHICLES PRODUCED BEFORE DECEMBER, 1987."

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brokencase
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Re: Scorpio AC fan always on

Post by brokencase »

I believe I have the revised manual schematic pages in my service manual that reflect the TSB change. I will try to scan and post this weekend.
I will also draw up my schematic for the 30 amp relay setup that I did.

I was thinking about you yesterday when we had a warm spell. I was testing the A/C. One thing I notice is that with this mod the engine temp actually comes down a few degrees when the A/C is on.

It definitely helps the A/C cooling, but it is still darn hard to get a hot black leather Scorpio interior chilled down.

My usual procedure in the Summer is to park the car in the shade (what little I can find at work lot) and crack the windows/sun roof a little. Then as I leave work to commute home I open all the windows to get things down to ambient.

Next step is to close all windows and turn on the A/C to 00 and recirculate, but leave the sun roof cracked in order evacuate any residual hot air up top.

Plenty of cool air from the A/C at this point but the seats are still radiating. About 20 minutes later into my 25 minute commute the Scorpio begins to feel comfortable cool.
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john keefe
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Re: Scorpio AC fan always on

Post by john keefe »

Well, the answer's obvious... once its comfortable, you gotta' drive the car around the block several times more to get full enjoyment. :D Unless that gets you in trouble for delaying home duties.
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Re: Scorpio AC fan always on

Post by john keefe »

On that M57... turns out my car's build date was March '88. I did find what looks like a single cooling fan relay with the same 4-pin (Hi-Lo) temp sensor arrangement on ALLData.

Best I can do at this point is to provide a link to the ALLData. There are several more pages with a complete Testing procedure which isn't in my '88 1988 Service Manual.

http://www.alldatadiy.com/alldatadiy/DI ... 7/41787826

Shows up when I tap the link, but that might only be because it sees my ALLData profile. Hope that works.

If I can, I'll try to draw up a schematic to show what the mystery relay on mine looked like. If you can do it in your head, the relay was 5-pin, with a take-off/splice into 31B-18 (BR/BK wire) to pin 30. A take-off/splice from 54-37 (BK/Y) to pin 85. Pins 87 & 86 were jumpered together, and sent to ground. 87a ("off" connection) was left bare. Seemed to be working fine, until corrosion started gradually turning the fan on earlier and earlier.

Those splices were just after the 3-way pressure switch connector to the harness, behind the headlight bucket, so physically "before" the diode.
Last edited by john keefe on Fri May 04, 2018 2:48 pm, edited 1 time in total.
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Re: Scorpio AC fan always on

Post by john keefe »

Going from 5-pin relay to 4-pin, the only difference is that 87a is eliminated. So, shouldn't the wiring positions be just the same for the two? 85 - 86 is still the "relay" switch, pin 30 is V-in, and 87 is V-out.

Sorry, just trying to avoid any fried circuits.

Thanks again for all the help!
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Re: Scorpio AC fan always on

Post by brokencase »

Here is a snip from the IMON Archives of the mod I spoke of earlier regarding the fan being triggered by the A/C clutch..

"There was a post yesterday from Todd McCracken regarding the electric cooling
fan on the Scorpio.

This fan, located in front of the condenser, is a two speed unit controlled by
two sensors and two relays. One sensor is located in the passenger side rad tank
near the bottom just in front of the 'horn that always works'. This sensor
triggers the low speed fan if the temp reaches 105C (220F), and off again when
it drops to 95C (173F). This same sensor has a second higher trigger point
(can't recall the temp), that kicks in the high speed if the coolant temp goes
over 105C (220F). The second sensor is located on top of the receiver/dryer (in
front of condensor, driver's side - long black cylinder with sight glass on
top). This sensor turns on the fan (low speed only), if the A/C pressure reaches
1703 kPa (247 psi), and switches off at 1303 kPa (189 psi).

On design flaw in the Scorpio A/C system is the fact that the fan does not
automatically kick in when the compressor engages. This is not a cause for
concern at speeds over 60kph (40mph), at slower speeds in hot weather this can
place a great deal of stress on the compressor. Head pressure can climb
dramatically which translates into reduced compressor life, added load for the
engine, and less cooling from the A/C. I have modified mine by adding a relay
that is triggered by the A/C clutch circuit and grounds the low speed side of
the rad tank switch. Big improvement in cooling (engine and you), on hot days in
stop and go traffic. (I believe FLM issued a bulletin for this mod)

Due to the location of the fan and the fact that it rarely sees any action
causes the bearing surfaces to dry and/or corrode. Best way to test is to spin
the plastic hub - there should be a slight amount of drag but a good spin should
allow the fan to continue turning for a few revolutions. If it drags, try
sliding the hub back and forth as well as in a slight circular motion to see if
you can free up the bearings. If this proves unsuccessful you will have to
remove the fan, disassemble and lubricate. This is all quite straight forward
the only potential headaches are the steel mounting bolts corroding themselves
into the alloy support frame (may have to drill out the broken piece and re-tap
or use short bolt/nut combo), and removing the 2 left hand bolts (tight spot).

Hope it helps and take care,
PKC"

I have the TSB 90-25B-27 WIth the manual revisions in PDF format but I can't post a PDF here.
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Re: Scorpio AC fan always on

Post by Ed Lijewski »

Could you post the pdf to Drive, Dropbox or equivalent?

".... as well as in a slight circular motion to see if
you can free up the bearings. If this proves unsuccessful you will have to remove the fan, disassemble and lubricate. This is all quite straight forward ".

The nuts and bolts free up easily enough but those only secure the motor to the fan frame. The motor cases on both year Scorpios as well as all year XRs do not disassemble by removing those bolts; the cases are stsked together quite solidly, enough to dissuade the DIYer from pounding on them. The front bearing can lubed (TriFlow, e.g.) easily enough but not the rear bearing.

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Re: Scorpio AC fan always on

Post by brokencase »

I would not hesitate to replace the electric fan on the Scorpio with one of the aftermarket ones on ebay if it came to it.. Mainly because I believe the newer fans blow harder and draw less amps. You can get a 14" one for around $25 that is ~2200 CFM.

I put one of the 10 inch ebay units on the Sprite and it worked out amazingly well.

You might even be able to do some mods to preserve the old Scorpio fan shroud/grill so it would still look stock.
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Re: Scorpio AC fan always on

Post by john keefe »

Thanks for tracking down that IMON topic. How'd you get into the Archives? Thought they were down for a while yet?

In case anyone else is thinking of trying this unique relay setup I found on my Scorpio... Not so sure its a smart solution. The coolant fan is always on any time the A/C is turned on. Doesn't matter how pressurized the system is. Good recipe for quickly burning up the fan.

Now that I've studied it, this "solution" just looks like a jumper to take power from the WOT cutoff relay, and send it directly to the lo-speed fan any time the EATC on A/C. This could just as easily have been done using a 10/15 amp mini-fuse.

The fan is already annoying as hell being so loud. I have a couple XR fans laying around, and they're all the same. Might spin easily on the bench, but in the car they all sound like you've installed a turbine, or its going to grenade. Doesn't seem like they even push much CFM.

It hasn't been hot enough out here yet to see if the 4-pin temp switch in the radiator is working OK, though I think the few times I drove it last Summer the fan did seem to kick on for longer and longer periods of time. Or, maybe that relay was just starting to go... I suppose if I have the time, I could take it out, hook up some wires, and read resistance when submerged in boiling water. PITA, though. The mechanical clutch fan looks to have a new clutch, and seems to be fine.

Looks like the better way to go would just take signal off the A/C compressor clutch, as mentioned in the IMON topic.

And/or, since I don't know how well, or if the 4-pin coolant temp switch system actually works, I'm thinking an alternative would be to bypass that whole arrangement, and just use an XR fan switch. Works just fine in the 5.0XR, but I also have a relayed in-cockpit switch for backup. I like the design-intent of the setup as stock, but too many variables to go wrong.

Any ideas?
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Re: Scorpio AC fan always on

Post by brokencase »

I have a local backup copy of the Archives that goes up to 1999.

I am happy with the A/C clutch activation mod. A/C is colder, and I have control of the fan by turning A/C on or off.

The only thing I don't like is the "electrical surge" that occurs when both the A/C clutch and the fan start at the same time.
Also Scorpio horsepower drop was always noticeable when the A/C was turned on. With this mod even a little more so as the alternator
is now putting out current to drive the fan.

It would be nice to know what the amp draw is of the original Scorpio fan.

I thought about putting an arduino board to control the fan relay so that it could manage the fan a little more intelligently.
The idea would be that it would watch the A/C clutch activation and then PWM modulate a FET to drive the fan and some variable speed.
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Re: Scorpio AC fan always on

Post by Ed Lijewski »

What year are your Scorpios? The 89 Scrorpio fan is the spiral blade model. It may both blow a bit more CFM and also.be quieter My car is an "88 and on low speed the fan isn't really out of the ordinary re noise, on high speed it is loud; but it very seldom operates on high (very high ambient temp/humidity/stuck in traffic...).

I've got an '89 style fan in good lube condition and also bench tested for good operation, and after switching connectors from an old '88 style fan I installed it but it wouldn't operate automatically. I unwrapped and double checked the splicing I made at the connector but goubd nothing amiss. So I removed it and reinstalled a good "88 fan. If I figure out how to get the '89 fan wired so it will run I'll istall it.

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