By on February 16, 2018

1989 Ford Taurus Electronic Temperature Control, Image: OP

Ryan writes:

Hi Sajeev,

I have a problem with the air conditioning not functioning properly on my ’89 Ford Taurus LX equipped with Electronic Automatic Temperature Control (EATC).

When I start the car on a warm day the AC can blow icy cold air immediately, but the temperature gradually rises to ambient temperature by the time I reach the freeway, and is bad enough that I turn the EATC off. When I turn on the EATC by pressing AUTO, it often feels like it’s blowing maximum heat. I have noticed that when this happens the AC compressor clutch is not cycling on and off. During the winter, the AC compressor clutch clicks on and off. The problem seems to be intermittent and only occurs during warmer months. Also, during startup, you can hear an audible “whirring” noise in the dash, and that started to sound abnormal about the same time the AC stopped working. By “abnormal” I mean it lasts much longer than it used to. I believe the noise I’m hearing is the temperature blend door being moved so the EATC knows the position of the blend door.

The pressure in the AC system is normal, and I have tried a functional test of the EATC, which showed no fault codes by lighting up all of the LCD segments (above).

I have tried swapping a lot of items, thinking there might be a problem with a temp sensor out of calibration, or a problem with the EATC controller, but nothing I have swapped caused the AC compressor to click on. I did not change the blend door actuator or the relay module above the radiator. This problem only seems to occur during the summer, which makes me think the relay is the problem.

1988 Mercury Sable Wagon, Image: OP

I have recently acquired another relay module surrounded by an entire 1988 Mercury Sable LS wagon that could be swapped in as a test, which I assume is a good part since the Sable LS only has 95,000 miles, and the Taurus LX has over 337,000 miles. Any ideas for what the fault could be?

Sajeev answers:

Thank the Heavens: someone else loves the first-gen Taurus/Sable! I’m still waiting for my dream 1986-88 Sable LS sedan with dark brown velour and digital gauges to surface in near mint condition…or the almost cocaine-themed “White Knight” Edition:

I weep for anyone who watches this Miami Vice inspired TV spot and doesn’t turn into a raging Lincoln-Mercury fanboi. But, once again, I digress…

You have a comprehensive understanding of the ETAC system, and your shop manual (unpublished photos) informed you of no faults, so I reckon your A/C clutch is worn and can’t engage at higher engine loads.  Original clutches won’t last this long, and remanufactured A/C compressors (with rebuilt clutches) for this era of Ford are a mixed bag in my experience.

The failure under freeway driving is what put it all together for me.
1989 Ford Taurus LX Wagon, Image: OP

Aside from one failed 1985 ETAC head unit in 1992, my time with Ford Electronic Automatic Temperature Control systems from 1972 to 1995 has been trouble free. For decades! The rest of the HVAC system is subject to wear and tear, but knock on wood, those electronics are rather solid. And the Taurus/Sable’s bespoke head unit is the coolest of the bunch.

Slap in a new A/C clutch or compressor/clutch assembly and report back!

[All Images: OP]

Send your queries to [email protected]com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

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39 Comments on “Piston Slap: Bullish on Ford’s Electronic Automatic Temperature Control?...”

  • avatar

    Sajeev, you need to spend less time joyriding with your cousin and more time writing Piston Slap articles.

    Always a pleasure to see more in this column.

  • avatar

    We sometimes forget just how revolutionary the Taurus/Sable were when they were introduced in late 1985. My late Dad bought two new 3.0-liter Sable LS wagons on my recommendation in his lifetime – 1986 and 1990 models. These followed a long string of Lincoln/Mercury biggies. Both wagons proved to be reliable. He said the Sables were the best-driving cars he ever owned, and he loved the look of the front “lightbar”. I drove the wagons too and although neither were fireballs, they were quite pleasant, roadable cars. By the way, the Taurus wagon pictured in the article has the slotted cop-car nosepiece.

  • avatar

    I wish some manufacturer would have the courage today to go in a new styling direction like ford did then. This angry appliance/disappearing window/slashes/mega grill trend cannot end soon enough.

    • 0 avatar

      Then there is a strong possibility that it can backfire, as with the 1996 Taurus. It remained a top seller, always in the top 3, but it was too controversial overall. I think the design has aged well, though, it looks down right normal today.

      Also, remember that there are limits as to where they can go and what they can do today with impact standards being much more strict. And I don’t just mean the front, I mean the whole car.

      • 0 avatar

        The 96 revision was a step down from the original models. My dad replaced his 86 Taurus wagon with a (I think) 2001 Taurus wagon and whereas the original was perfectly sized, the new one was uglier, larger in every dimension except actual usable space, and wasn’t as reliable. He still owns it but only others drive it for him now. [edit] not I am remembering failed transmission in the old car. Doesn’t matter, still prefer that one.

  • avatar

    I love it, so nice to see others interested in keeping an earlier Taurus on the road. I wish the OP luck in fixing the A/C.

    I finally installed the rear struts/springs and new sway bar links on my 1995 yesterday. With new struts/springs at all four corners, the car drives great. Bumps no longer upset the car’s composure, its much more controlled and stable. The old units were original with 237K miles/23ish years on em, they long overdue for replacement. And, no more SAS (saggy @§§ syndrome)!

    I want a 1986-1988 Taurus sedan again. I have had several early ones, and I hope to have one again.

  • avatar

    It always seemed like the Taurus had foggy headlight lenses, even when compared to other Ford models.

  • avatar
    SCE to AUX

    You’re driving a 29-year-old car; time to part with it.

  • avatar
    bumpy ii

    I’m thinking there is also a problem with the blend door, specifically the connection between the door and the motor stripped out.

  • avatar
    Add Lightness

    9 comments and still nobody has mentioned the wonderful SHO version of this chassis…

    • 0 avatar

      It appears the wagon pictured has the SHO/Taurus Police Interceptor grille with extra slots in it. Very sharp.

      Sadly the modern equivalent (at least in my mind) Fusion Sport (2.7 Ecoboost V6, AWD 325 horsepower and a husky 380 lb-ft of torque) is already pretty well discounted from what I’m seeing at local Ford dealers. Even a hot rod sedan isn’t selling in this current market.

      • 0 avatar

        Actually, the SHO didn’t get the slots – only the police versions.

        • 0 avatar

          Darn I was sure they did for increased cooling and better breathing.

          My bad.

        • 0 avatar
          DC Bruce

          Police versions had the extra slots because more airflow was needed to ensure adequate cooling airflow during long periods of idling, which is part of police duty. The electric fans sucked air through the grill; under way most cooling air was deflected upward towards the radiator by the chin spoiler. Cooling was absolutely fine at speed with the stock setup (although I admit I never drove in the desert southwest in the summer).

          BfDC: SHO owner 92-02

        • 0 avatar

          The police grille was a popular mod for first-gen SHO owners, but didn’t come stock on the SHO.

        • 0 avatar

          Some early models (some MT-5 and L models) had a full slotted grille in the front (not the cop car grille). I’ve only ever seen it in a brochure. But here’s an MT-5 with one, on Curbside Classics:

    • 0 avatar

      Wonderful to drive, not to own. My ’89 SHO was by far the least reliable car I’ve ever had. And one of the issues was various climate control parts. I had the compressor fail twice, the compressor clutch fail once, and the blower motor fail once.

      But I have to say that when the whole system was working the SHO’s EATC was very good, better than the ACC systems in any cars I’ve owned since that were not premium or luxury brands.

      • 0 avatar

        I’ll second that. Although I never had any trouble with the climate control. Worst car I ever owned by a wide margin, and I’ve owned an early water-cooled VW.

      • 0 avatar

        And you’ve admitted that the one you bought had been trashed before you got it.

        I had a customer that had 2 of the early SHOs that he ran for over 200k each w/o any significant issues other than the POS Nipondenso and Ford produced licensed versions of the coil and compressor.

    • 0 avatar

      There is a mint, black ’95 SHO running around in my area. Plates say “2 4 SHO”…always thought that was really clever.

  • avatar

    Check the air gap on your compressor with a feeler gauge. The big clue was that it works when cold, then stops when it’s hot. Google “how to check air-gap on Ford compressor” and you should be all set. HTH!

  • avatar

    For how many of these cars that were sold, they virtually don’t exist anymore. Especially 1G Sables. Like dragons or unicorns, I know what they look like, but they are nothing more than mythical now.

    a 1G Sable still looks like a spaceship to me.

    • 0 avatar

      Most of them were killed by transmission failure with generous side helpings of leaky heater cores (10 hours labor to replace!) and Essex V6 blown head gaskets.

      • 0 avatar

        Yep. I cut my teeth working on them. They weren’t built for longevity.

        Though, if you got a 3.0L vulcan version, they could live long enough for the body to rust out.

      • 0 avatar

        I owned an ‘87 Sable wagon, purchased new, along with a 7 year 60,000 mile warranty. We went through 3 transmissions, one head gasket, one A/C compressor and one heater core, as well as innumerable small items like power door locks, window lift regulators and other parts. Paid $15,000 new, traded it at Ford dealer for $2600 toward a new ‘95 Windstar. Had I not purchased an extended warranty, it would have been a disaster.

  • avatar

    I find the ‘auto’ setting on A/C systems never seems to work as I’d like, much prefer to use the manual. On my Lexus, when I push the auto function, it simply goes to full blower, annoying as heck. My Volvo had such a crappy HVAC system they actually placed a fault-code indicator light on the control panel.

    • 0 avatar

      If you left it on auto, the fan speed should decrease once the selected temp is reached.

    • 0 avatar
      Tele Vision

      My 2007 CTS-V does that, too: hit the ‘Auto’ button and it tries to get the cabin to the selected temperature as soon as deafeningly possible. I’m not dying of heat or cold – I’ll be ok for the extra few minutes it takes. It does work well but it’s no laminar airflow system – more like a shrieking turbine. It does, however, modulate once the temps near the desired value.

  • avatar

    Sometimes the AC clutch can freeze up from corrosion. There is a fixed plate and a moving plate. The moving plate runs on a toothed hub on the AC shaft. The electromagnet coil pulls the moving plate against the fixed (on the pulley) plate. If the hub to plate surfaces get corroded then the moving plate… can’t. Try some penetrating oil on it.

  • avatar

    The problem is the Nipondenso clutch coil. As they heat up the resistance increases and/or a short occurs and it is unable to create a strong enough magnetic field to pull in the plate. Unfortunately the coil is pressed onto the nose of the compressor and if you do it/have it done by the book it is a several hour job. However if you know the trick it is a 45 min job.

  • avatar

    Long time reader, never felt compelled to post here… until now!

    TL;DR – replace your *ignition switch*!!!

    Long version:

    My father purchased an ’88 Taurus LX wagon as a lease-return off a local used car lot in early ’93. Car had ~90k kms (~55k mi) on it at this point, and being an LX, was fully loaded (this same auto HVAC system, cross-spoke alloys, digital dash, etc.). My dad low-balled the dealer at the end of the month, using the notoriously fragile Ford transaxle (which was already starting to slip noticeably) as a negotiating point. One week later, my Mom had a new Valentines Day present.

    As a 10 year-old kid growing up in the back of a ’78 L20B 4-speed Datsun 510, it might as well have been the starship Enterprise. My friends, equally in awe, used to announce every KPH clicked off by the digi dash as my mom accelerated to cruising speed on the way to cub scouts (47, 48, 49… 50!).

    The car served us well for the next 20 years, accumulating some 340k kms total driving between various hockey practices, school outings, my Mom’s office daily (3 miles round trip!), and several family road trips south, until finally I found my parents a Lexus and the Taurus became our 2-month-per-year “cottage car”. In exchange, it only ever asked us for 2 fuel pumps, 2 alternators, front rotors, one set of Bosch platinum plugs, one repaint (peeling clear-coat), one heater hose, and a rebuild of the aforementioned transmission at 98k kms. Aside from these issues, it ran like the proverbial Casio watch. In fact, I believe it still has its original plug wires.

    That was until two years ago, when the HVAC started acting up. As our subject posts, the car would cycle on to MAX heat (32 deg C) a few seconds after starting the car, 4 times out of 5. Curiously, a few thousand k after this started happening, the IP would fail to illuminate, until you fiddled with the ignition key a little. Piecing these two tidbits together, my father decided to replace the ignition switch/key tumbler with a new unit from our local AutoZone (or equivalent). Most likely from China…but I digress. Total cost? Including “good guy” discount, $38.

    Result, both problems cured. Car has perfectly functional ignition and HVAC systems.

    Only downside is we now have a different ignition key vs. the rest of the body. Which, considering the tailgate was always a different key (for a reason only some junior Engineer at Ford, circa 1984 knows), means we now have 3 keys for the car.

    Best car I’ve ever known.

  • avatar

    Back in ’94 I took over my mother’s ’89 Taurus GL. It had 26k miles on it. Between late ’94 and mid-’99 I put about 85,000 miles on it. By the time I donated it (I couldn’t knowingly sell that piece of crap to anyone), it was on its fourth (AXOD) tranny, its fourth power steering pump, its second head gasket and it still leaked every type of fluid imaginable.

    Amazingly I bought another Ford after that: A ’99 Ranger XLT Supercab w/4.0 V6 and 5 speed. I still have it and have 313,000 miles on it. It’s bulletproof. Ford does trucks well I believe. I doubt I’ll ever buy a car built after 1970 from Ford again.

  • avatar

    I really want to find a 1986 Ford Taurus LX Wagon in red and do a restoration on it. Too bad these cars are so hard to find today.

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