1963 AC Evaporator Drain & Follow Up

Good morning Bill –
Thank you for all the advice you provide to us Lincoln car owners. I have also had great help from your sales staff when purchasing replacement parts and assistance with installation advice.
My short question is “where is the AC evaporator drain located on my ’63 sedan?”
The long part stems from nearing the end of our family 2500 mile road trip to the 2015 Eastern National meet. We had been using the AC most of the trip without issue. Good cold air (converted to 134). Passing through Ohio, it was quite stormy, humid but not terribly hot (around 80). AC was started early in the day around 10 AM. About 1 hour later, I noticed condensation around the AC vents, then around the radio selector keys. That afternoon, there was a cool mist vapor which started coming out of the AC vents. I quickly turned off the AC which stopped the blower and the vapor stopped. Tried it again 5 minutes later and even my 6 year old in the back seat noticed the “smoke”. I was trying to postulate as to the cause. Next day I ran AC at 2/3 without further issue.
Fast forward to the question. Could the evaporator drain be plugged allowing water to back up? I don’t recall ever seeing a puddle of water under the car like my modern vehicles do when running the AC. I have NOT seen water spilling into the interior of the car.
Thank you in advance.
Phil
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Hello Phil –
We are pleased that you are happy with our service here at Lincoln Land. Be assured also that our staff is pleased to have you as a loyal customer.
The condensate drain on your 63 should be found behind the engine at the extreme lower firewall area. It will be under the evaporator area and may not be easy to see immediately. If the a/c has been operating and cooling properly for awhile especially in the Fresh position with a hot humid outside condition some condensate should be seen draining from this area under the car and onto the ground. The dripping condensate will help you locate the drain for cleaning any partial clogs. If the a/c is operating properly and no draining at all is noticed you will need to locate and clean the drain.
Usually any vapor ( along with a slight coolant odor ) that is seen exiting into the passenger area though is indicative of a heater core leak . Temporarily bypassing the heater core and driving the car as usual will prove or disprove this possibility. On a 63 though, the evaporator is quite close to the ducts and therefore some vapor and condensing may be seen on the a/c outlet grille chrome under conditions of high humidity. However, there is another possibility that can occur to all a/c systems. The evaporator can freeze up into a block of ice with some droplets carried off into the air stream. This is usually followed by a drop in blower volume and a rise in cooling air temperature at the vents. If this freezing is in fact happening, a large amount of condensate will be seen on the ground after the engine is shut off and the car sits for a while. This can happen on your Lincoln if the programmable thermostatic switch is faulty, out of adjustment or bypassed because of a control switch failure etc. You can de-ice the evaporator ( if this icing is happening ) while driving by selecting Heat or Vent control position with the blower on high speed. This will turn off the compressor and yet allow the blower to melt any ice that is present. The 63 Shop Manual contains the vacuum and electrical diagrams along with some photos. Some skills and understanding of the operation are necessary in order to diagnose and correctly pinpoint a possible problem. I would advise you to do the above simple observation tests before condemning any component. I hope that this helps you.
Sincerely,
Bill
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Bill,
You are a Gentleman and a Scholar!!
Thank you for your detailed answer. It’s all starting to make sense now. All data seems to point toward an iced over evaporator core.
Sincerely,
Phil