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1988 Town Car AC Issues


I'm hoping for some advice, maybe this is a vac leak I am overlooking, or something else. I am trying to gather information before getting deep into this car, dash pulled to get to the heater box, etc.


It's a 1988 TC.

Issue is, switching from VENT to Floor, HI-LO, or Defrost, only 25% or so of the air is directed from the vent to either the floor or the windscreen. The other 75% of the air still flows through the normal vents.

The thermostat works fine. Cold air, hot air when I want it. A/C works fine.

It seemed to me to be a vac leak. However, there does not appear to be a vac leak.

Another person's opinion is that it could be a twig in the heater box, or some sort of other debris. He is recommending taking the dash apart more to explore further....

I'm still thinking it's a vac leak, since it is directing some air to the windscreen when I want it, and some to the floor when I want it.

Anything come to mind?




Hi Richard -

The ac/heat control system on your 88 town car is vacuum controlled as you know and is designed to default towards Defrost in the event of loss of vacuum. If you have 75% of the air flowing out of the a/c Vent ducts when no air should flow from these dash vents then I would advise you to first inspect the vacuum lines for correct routing and attachments to the correct vacuum motors under the dash. At this time the individual vacuum motor operation and their attachments can be inspected as well. If you have recently purchased the car or do not know the repair history, there may be many other possibilities such as previously misassembled components etc. but the above is easy to do from under the dash without removing the heater plenum assembly. To diagnose the system properly though I strongly advise to do so with the correct Shop manual or A/C manual at your side. If the above does not help please contact us for further advise. We can of course also arrange a shop manual or any necessary parts to be shipped to your address.