« 1964 Continental "Mysterious Leak" | Main | 1977 Mark V Overheating Issue »

1976 Lincoln Town Coupe ATC Problems And Follow Up

Hi Bill,

1976 Lincoln Town Coupe ATC blower problems. Hope you guys are well. May I tap into your vast knowledge of my Lincoln ATC system again please? Ever since I got the car there has been a intermittent fault with the system in that the blower fails to operate in both Low and Vent positions only, rest OK., very sporadic, usually after start up after a run, not normally after an overnight start up. Since fitting the ATC box from your good selves, the problem seemed to go away, (more than likely a coincidence) with the system performing faultlessly. Unfortunately, whilst driving home from friends on a particularly cold Saturday night a week or so ago, the system, which is normally left on Low all the time, did not start up when the engine warmed as normal. (The outward journey was trouble free with the usual sumptuous warm environment) The system (blower??) would work as normal in High, Defog and Defrost, but not in Low or Vent. Usually, when this occurs, the system "repairs itself" overnight and all is well the next day. Not this time however. It does seem to be the blower switching system, as you can hear the vacuum system and doors operating as normal. I even seemed yesterday to get a very gentle waft on both Low and Vent, which then seemed to stop all together. All the wiring and connections behind the control unit seem to be sound. Would a relay or the blower resistor cause such a problem? Must admit some of the wiring at the resistor connector block does look a little fried!! Have not had a chance to check it out properly due to the inclement weather. Boy what a wimp!! Any ideas you have to solve this problem would be very much appreciated. Thank you.

Kind regards to all,

Jim

----------------------------------------------------------------------------------------------------------------

Greetings Jim -

Yes, loss of the LOW operation can certainly be caused by a fault at the blower motor resistor pack or a relay on the firewall. If you have spotted a possible bad connection at the resistor connector as you have stated, that is where you should begin. The resistor should be removed and the coils inspected carefully for breaks etc. and the individual pins at the connector cleaned as well as the female ends removed and tightened one at a time. A badly damaged connector plug or wire contact pin would need to be replaced. If repairing that connection does not correct the problem, the Range Relay on the engine side of the firewall should be properly tested next. The wire colors and internal contacts are shown in the Factory Shop Manual wiring diagram. The other relay in this circuit is the High Blower Relay but I would suspect the Range Relay first in your case. These relays are very popular fail items and we offer a rebuild service for them or replacements if they are too far gone. These first inspections should reveal the issue. If not, email us back and we will go to the next steps. A further good practice after the repair is to perform a blower motor draw test with an ammeter to be sure that the blower motor is not drawing excessive amperage which could cause future wiring problems. Let us know what you find Jim and we will be ready with any necessary parts that you may need.

Sincerely,

Bill

----------------------------------------------------------------------------------------------------------------

Hi Bill,

Thank you for the fast response. I will check out the items you mention as soon as I can, and let you know the outcome. You guys are life savers, especially for us overseas with no such thing as "Lincoln-Mercury" dealers.

Take care,

Jim

----------------------------------------------------------------------------------------------------------------

Bill -

On 7th March 2016

I have done a little investigation as per your suggestions on the blog.

Firstly blower resistor connector: This has proved impossible to separate from the resistor module, and not wishing to do any damage (without replacement parts in my back pocket), I removed the resistor pack with the connector still in situ. The actual resistor module seems in excellent order. All the coils are present, without any breakages or signs of touching, overheating, scorching or general deterioration. In fact it looks brand new! However, the wire which I mentioned as looking somewhat fried in my first blog enquiry is actually terminal number 6, orange with black stripe. (All the other wires look fine from the outside) The insulation at the connector end is quite badly deteriorated for about 1/4 inch from the connector. I am unable to ascertain whether the actual male and female connectors within the units are damaged or corroded.

However, when I fitted the bits back together, horror upon horrors, the High auto function had also stopped working, but not the two demist functions, no doubt due to me messing around with the orange and black wire. Before I put the car away, I sprayed WD 40 all over the connector block in the hope of loosening the connector from the resistor module for the next attempt. When I reached the car storage facility, I tried the High function, and it worked fine. This will need to be check out of course, but I am reluctant to do too much work without any necessary replacement parts, fearing being without heating. Which leads me onto a question as to whether or not you can supply new connectors ready wired up to splice/ join into the wiring harness and push into the resistor module?

Secondly, the range relay. Not easy for me to check out due to lack of facilities. I am tempted to risk buying one to try it, as I feel that it is the most likely contender. Do you have these in stock?

On 10th March 2016

The High auto feature is still working great, and reduces the blower speed to quite low speeds when the temperatures are balanced. Tried again today to separate the connector from the resistor module, without success. The unit is in a difficult place for this old guy to get a good grip onto the connector, to apply sufficient force to separate the two, but if I could remove the whole assembly from the car, it may well be much easier. However, this would of course need the seven wires to be severed!! Oh dear. This is really frustrating. Oh for the hands and strength of youth. (And other things!)

To clarify: Please let me know the cost of: 1) replacement blower resistor connector with fitted wires, if these are available, or would it be feasible to cut the wires close to the actual connector, remove the assembly, separate the connector and resistor module, fit new female connectors to each wire, and re assemble. What would you do? I am afraid I don't know what bits are available. 2) replacement blower resistor--just in case. 3) replacement range relay.

I can then decide how to proceed, and have the parts with me before getting "stuck in". Hope all that made sense. Thanks again for all the help and advice. Very much appreciated.

Look forward to your reply,

Kind regards to all,

Jim

----------------------------------------------------------------------------------------------------------------

Hello Jim -

Sorry to hear that you are having such a hard time with that resistor connector. A bad contact here has obviously heated and fused some elements together. If you are certain that a forced separation will destroy the connector plug and resistor pack we should be able to find and send you an undamaged connector and resistor with a length of the original wires attached and ready to splice. You could try to cut or saw your connector apart at the melted location in order to save some or most of the original wiring and attach them to the new connector and new resistor. You may then only need to splice one or two wires ( the ones that have the burnt connections ). These wires can be removed separately and one at a time as necessary from the connector by tripping a built in locking tab pin at the connector with the connector unplugged. This way you will be able to choose the correct path for the situation at the time of repair and have all necessary wiring at the ready.

As for the relay it would be easier I believe to send it to us for testing in order to verify a fault and then rebuilding as and only if required. I strongly advise to send in the blower high speed relay as well for testing here. We then could send them back to you with the above mentioned replacement wires, replacement resistor and replacement connector plug. I could even advise the color of wires to temporarily jump to lock the system on " low range " blower speeds. That way the car can still be used with the climate control mostly operating operating. Let us know what would be best for you or if you have further questions.

Sincerely,

Bill

----------------------------------------------------------------------------------------------------------------

Hi Guys,

Well we've done it! I managed to fit the refurbished parts on Good Friday without any problems. The main help was me seeing, from the resistor connector you sent, that there was a second clip fastener which is hidden from view when fitted in the car, and even with the resistor pack removed from the heater housing, not easy to see, without removing it from the car. When I discovered this, and released both clips, guess what, yes, the connector was easily removed from the resistor pack. Talk about feeling a fool!! Anyway the true extent of the damage was now easy to see, and it was a wonder the system had been able to function at all.

It seems that the male connector for number 6 connection, Orange and Black wire, had rusted through from the inside, (possibly due to the car not seeing much use during the 10 years prior to me buying it), and indeed there was little left protruding through the fibre/plastic casing of the resistor, the resultant resistance at the connection, and subsequent heat generation, causing the plastic connector (housing the female connector), to melt away, together with a substantial amount of sleeving from the wire. Evidence of sparking too. What a mess!!

As the connector was now separated from the resistor pack, I was able to fit the original 5 wires into the "new" connector, as per your suggestion, and leave the 2 heavy duty cables/wires you supplied in situ, with these spliced into the wiring harness. Job done. Of course the relays were a doddle to fit, and I am pleased I now have these refurbished too. Can only help the situation.

All wired up, and hey presto, the unit functions a treat. What a result. Splendid! A nice warm cabin environment, achieved in near silence. It's funny, when you manage to repair such problems, the system, whatever it might be, always seem to work much better than it before. Not hard to believe in this case!

Unfortunately I ran out of time to do a current draw test on the blower, but will do that ASAP. Just wished the weather would warm up a bit.

It only remains for me to thank you guys for all your time and trouble. I am sure you know how much it is appreciated.

Take care, and best wishes to all,

Jim

----------------------------------------------------------------------------------------------------------------

Hi Jim -

Congratulations on the repair! We love to hear customer success stories. The blower draw test is good to do in the near future to ensure that the blower will not damage the wiring again if it is in fact over drawing. If it is within specifications, the connection that caused the burnt wiring plug was faulty for some time. Enjoy your Lincoln Jim.

Erik, George and Bill

----------------------------------------------------------------------------------------------------------------

Hi Bill,

Managed to do a blower draw test, at last, on Friday. Yippee, within tolerance, at 22 amps on high blower speed. So all is now well. I know you guys would appreciate knowing the results. Seems it was the corroded terminal in the resistor module causing the trouble.

Take care,

Jim

----------------------------------------------------------------------------------------------------------------

Hi Jim -

Excellent results on that test Jim. Case now closed, time too enjoy that nice Lincoln.

Sincerely,

Bill

----------------------------------------------------------------------------------------------------------------

Hi Bill,

Well the old ATC is playing up again, just as I thought we'd solved it. I've now lost the high blower range. It does seem similar to Dan's problem with his MK III below. Here we go then: when you move the control lever to de frost, the system will switch to full heat and the blower to full speed, but after only a few seconds running at full speed, the blower will switch out altogether, or at the best will run exceptionally slowly. I experienced this, if you remember, when I first examined the wiring at the blower resistor, thinking that me messing around with the wires had caused the problem. However it righted itself at the time and has been fine after the fitment of the refurbished resistor module and relays. Indeed it allowed me to check the blower current draw using the de frost setting without any trouble. So it does seem to have been in the background before I replaced these components. It also manifests itself in HIGH AUTO(when selected, blower will run on "intermediate" speed, then suddenly move to high speed, and again drop back to intermediate, were it will stay for the duration.)& LOW AUTO(when selected will run at very low speed and then after a while will surge to the high lower blower speed, and again after short time drop back to minimum.) I don't know if it's my imagination, but whilst the blower is running at any speed, it does not sound to be consistent, but with a very slight surging or variation in speed?? If I jump into a hot car with the system set at low auto, there is very little cool air admitted to the cabin, and then after about 5 minutes of driving the blower may or may not suddenly move to a high setting, and allow more cool air in. In high auto the same occurs, but with an initial slightly higher blower speed. I am unable to achieve max a/c. Then again, sometimes during the drive, I will get cold air?? The whole scenario is very unpredictable. I despair!! Continuity check of main switch is OK, and the system works, after a fashion, in all selected functions, it seems that the system just cannot decide what blower speed to utilize to fulfill the required function. I do hope all that made sense. As always, any ideas you have will be very much appreciated, and if you need any further info I am only too willing to help.

Kind regards to all, take care

Jim

----------------------------------------------------------------------------------------------------------------

Jim -

Your description sounds like a high resistance somewhere in the blower circuit at the resistor multi plug or one of the relays. I would check for heat at all of the above connectors ONLY at the time that the fault is occurring. Of course we stand behind those parts that we have previously rebuilt for you. Before the above tests are done you should consider two other possibilities. The blower motor could be overdrawing amperage only after it has been on for awhile and is overheated. This in turn of course could damage any connections in the circuit. The blower motor draw test may need to be repeated and carefully observed with the blower motor on for a period of time. Power to the high relay from the battery is through a fuse link under the hood (bonnet). A faulty fuse link connection ( not completely failed ) could cause an intermittent relay feed. As I am not back to Lincoln Land until October we may need you speak with Erik for the fuse link location if the important blower draw test proves that the motor is drawing correctly in the lower 23 amp area when hot. The parts that we rebuilt can certainly handle the normal amperage draw. Let us know when your testing is done and you have more information in order to proceed to the next step.

Sincerely,

Bill

----------------------------------------------------------------------------------------------------------------

Hi Guys,

Thank you for the usual speedy response, and your patience and advice.

I have been attempting to do the tests you suggest. Unfortunately I am unable to get high blower speed to check the amperage draw, as at present the system will not provide this facility, apart from about 2 seconds duration when defrost is first selected, dropping almost immediately to very slow.

What I failed to mention last time was that in vent the blower works perfectly well, (This being the only position were it does) and, as it should, on the pre-determined speed and at a constant speed. So what I did this morning was to start the car and select Vent, jumped out and checked the current draw with the blower running at this speed. Result was 9-10 amps., and left the switch in vent for the following 1/2 hour drive. When I stopped I left the engine running and jumped out to check the blower draw again, and got the exact same result of 9-10 amps, so it does not look as though the blower is getting hot.

I have found the fusible link George referred to, near the passenger side firewall, with the yellow band identification. Looks a bit scary!! Don't know what to do with that. Is there anyway to check this out?

With the system switched to defrost, which is the position which seems to highlight the problem the most, I checked out the terminals at the resistor module and both relays.
All seemed to be well without any signs of heating. Please be aware that after fitment of the two relays and the resistor module, I did use the defrost setting to get the 22 amp reading for current draw, and at the time the system was running at full blower speed, so I am sure the relays and resistor module are performing correctly. I also say this because this very same problem, re very slow blower speed in defrost and other positions, did occur prior to the fitment of these components, and first became noticeable after my first attempt at checking the terminals on the resistor pack, because I thought it due to me messing with the wires. However this rectified itself, only to resurface on my first attempt at the current draw test after fitment of the new components. Again, rectified itself sufficiently for me to do the successful draw test later, only to re-occur later with fluctuating, "slow then high and then slow speeds" in both low and high auto, "steady speed" in vent, and then "initial high speed immediately dropping to very slow speed" in defrost. Oh boy, what a confusing mess!

What I have found purely by accident, whilst attempting to trace a rattle under the passenger side dash and burning my finger in the process, is that the compressor clutch relay (situated to the right of the ash tray) connection(s) is/are getting very hot. This occurs only when the compressor is switched in, the relay remaining cold when the compressor is switched out. I don't suppose this will be connected to the blower problem will it? After all the problem only seems to be prevalent in the positions when the compressor is switched in. May be coincidental. This will have to be looked into at a later date, as the weather has closed in again, with rain, rain and more rain. I will not use the compressor until this is sorted.

Over to you with the hot potato. (Only joking). As always any suggestion/advice you can give would be most welcome. Thank you.

Best wishes,

Jim

----------------------------------------------------------------------------------------------------------------

Hi Jim -

A much better way of testing the blower motor amp draw is with a 10 gauge wire properly connected to the battery positive terminal and then through your ammeter gauge directly to the blower motor connection closest to the motor itself. Do this with the engine and the key in the off position. That way there is no other resistance involved, only the blower motor itself. This should be done for a reasonable period of time with a battery charger keeping the battery fully charged during the test. Any fluctuations in blower speed can also be noted.

The fuse link can be checked for excess heating by hand on the wire wrapping with the system on and the Defrost selected to maintain high blower. At the same time the link can be wiggled slightly to check for a bad internal connection. The compressor relay should not affect blower speeds or heat to such a degree that it literally burns your fingers in my opinion. If you believe that the compressor circuit could be a culprit you could pull that fuse out from the fuse box for a test without that circuit involved. Did you already include checking for excess heating of the multi plug and wire splices that you connected when you installed the new resistor and multi plug?

If nothing at all is found with the draw test or any other testing, we may need to discuss sending the relays back here for inspection.

Sincerely,

Bill