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June 26, 2019

1970 Sedan Horn Issues, 1989 Town Car Loosing AC At Acceleration

Hi Bill,

Hope things are good in the North!

Several questions. 1st, (the 1970 Sedan continues to be about my favorite... I love that car for lots of reasons, and it has a great story). The air horns aren't working. This happened once before and I asked a garage to look at it, and they said they work fine, and it did. Now, the relay can be heard clicking, but no horn. Any thoughts?

2nd, the 1989 has the typical problem of under acceleration all A/C is lost and much heat comes on thru the dash. I have read the manual and it says "vacuum leak." Great. Do you have ANY idea where to start looking for this or and suggestions? Also, the other day when driving the 1989 the horn started to blow. I tapped the horn button and it quit. A day later, sitting in the carport at the funeral home, it starts again, all on it's own. Same deal, tapped the horn button and it quit. Now only one of horns blow and it sounds like a clown car. Any thoughts on fixing the problem and can I put older "Lincoln sounding" horns on it?

Many thanks and best to all,

Carter

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Hi Carter -

Good to hear that you love that 70. I still miss that one.

I assume that the electric horns are working o/k. I showed you where the toggle switch is that changes the horns from Air Horns to Electric. Your description sounds like an " intermittent" electrical problem at or inside a relay or at the air valve solenoid at the air tank. Next time it quits have an assistant operate the horn so that you can trace where this " click " is coming from under the hood. If it is from a relay, tap that relay with a screw driver. If the horn then operates it can be an electrical contact at the relay or a bad contact at the points inside the relay. If the click is coming from the solenoid valve on top of the air tank the problem could be at that tank assembly or the pump is not building air pressure in the storage tank or the storage tank or solenoid ( located on top of the tank ) has a leak and will not operate the horn when the engine is first started because it needs engine running time to generate air pressure. If so, the leak will drain pressure soon after the engine is turned off.

Your 89 town car will revert towards HEAT if you have a vacuum leak in the system. Vacuum is needed for a/c to remain in the COLD position. Under acceleration the engine looses vacuum and if the a/c control system has a leak it will revert to the Heat mode. The most common point of a leak is at the vacuum valve under the hood that prevents vacuum from migrating back to the engine under acceleration. When you release the accelerator pedal vacuum to the control resumes. This valve needs to be examined and tested.

Your description of the horn problem indicates to me that the switch is shorting and turning the horns on. Tapping this switch makes the short disappear for period of time. Warpage or binding near the switch and some normal in car heat cause the fault to return at a later date. The switch would need to be examined to find out if is repairable or needs to be replaced. Other horns can be used in place of the 1989 originals.

Sincerely,

Bill