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78 Mark New Owner Heat AC Question

Bill –
I just bought this Mark V, it has been sitting for 12 years in a controlled climate environment. When I started it, it was revving fairly high, thought maybe the choke wasn’t releasing and tried to get it to release but it wouldn’t. So just before I started to drive it I played with the heater controls and low behold when I put it on economy vent it idled down, couldn’t get the heater to work but it stopped the revving and drove decently for the trip home. So, is there something with the vacuum system that needs attention or is the issue else where?
Jim
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Hi Jim –
Welcome to the land of Lincolns and congratulations on your Mark V purchase.
What have you checked so far to diagnose your issues? Your sticking choke could be the result of 12 years of inactivity and/or related carburetor adjustments. I have no idea from the information that you have provided if any vacuum system needs attention. Complete loss of vacuum to the heater / air conditioning system though will immediately result in full heat and defrost. A ” no heat” problem could be as simple as low coolant in the engine cooling system, a sticking (open) engine thermostat or sticking (closed) water shut off valve. I also do not know what “I played with the heater controls” consists of. The Economy Vent selection will disengage the a/c compressor and lower the idle somewhat. If you are repairing these problems yourself, a factory shop manual is strongly advised. We can arrange for these manuals to be sent out to you.
Sincerely,
Bill
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Sorry for the confusion Bill, I will try again.
When we started her at the sellers location you knew the choke was on, so I tried to release it by the usual means of tapping on the accelerator but this did not work after several attempts. After the money exchange I then proceeded to an oil change location and changed the oil, had her greased and all fluids checked again with everything being normal ( I will replace the radiator fluids and flush in spring). With it sitting so long I figured there is something with carb. I then proceeded to an auto parts store and bought some Sea Foam and added it to the tank of #1 fuel I added. When I restarted it at the auto store I tried the heater controls and as I moved heater selector switch you could hear the vents opening and closing at each position but when I put it on economy position the car idled down which made me happier but no fan. I wasn’t to worried then as it was not going to be that cold between Medicine Hat Alberta and Rockglen Saskatchewan where I live. We stayed the night and when I started it in the morning it fired right up but then when I moved the heater selector switch on the heater control it again started to rev up on other positions so I put it back on the economy position and all was well for the whole trip and traveling at 65 mph I obtained around 16 mpg which I wasn’t to bad I thought. Heat came through the vents on its own but still no fan for the trip.
Now after being home and being parked for a few hours the head light covers opened up indicating a vacuum leak I think… I have since started it once since bringing her home and played with the heater selector and it still revs up in all positions except economy. The head lamps close immediately once you start it but whats interesting with this is that when I purchased her they were closed and being parked over night they were closed still in the morning so not sure what is happening with the vacuum system as when I shut the car off now they go back open in a few hours.
With all that, the car was purchased from a senior couple and she has only about 38 thousand miles so I couldn’t pass this car up for 2,500 dollars and knew there would be some issues such as the vinyl roof needs repair and obviously a full tune up which will happen in the spring but hoping you can shed some light on the issue at hand with the heater controls/fan as to why this is affecting the idle, no fan and head lamps open. I did find on line the electrical and vacuum manual on a site and will print out but I didn’t know you had manuals etc for one to purchase, is their an online store to view your products?
Its a beautiful car that needs some attention just want to do it right. I like to try things on my own but I suspect it should be taken to a professional such as yourself and get it done.
So hope this is a better explanation.
Jim
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Hi Jim –
Your latest information certainly helps to appreciate what you need to do to correct the issues that are appearing on your Mk V. It does look like you will be busy. The suggestions that we made earlier still apply.
These problems that you are experiencing need to be dealt with one at a time in a logical manner and sequence. Each faulty item or system should be examined separately to verify the fault and then you need to read the “proper” shop manual to find out exactly how it operates and to learn where the various components are located on the vehicle. Then each suspect component needs to be tested as per the manual starting first with the easier items to test or items that are suspect. These above methods help to avoid replacing good parts. New parts now are scarce and expensive. As an example of testing the components, the vacuum operated headlamps are known to leak vacuum from the vacuum motors at the grill area. These motors are a good starting place to test separately for vacuum leaks with a hand held vacuum pump. A vacuum leak can occur anywhere that vacuum is routed. Some systems have several leaks that must be found.
If you are unable to do these tests yourself and are using a local repair shop, that technician will certainly be able to use your shop manuals to save you time and money.
At Lincoln Land we have many good used and some new parts available for your car whenever you need them.
Sincerely,
Bill

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