Model: Town Car
Engine Size: 4.6
Refrigerant Type: 134a
Ambient Temp: 85
Country of Origin: United States
How do you discover the pressure required to activate the low pressure cut-out switch?
That is what is the minimum pressure to get the compressor to run?
A simple switch-controlled CCOT system would engage above 50 psi. Luxury cars may have more complicated controls.
If the system static pressure is +45 psi and the compressor still won't engage, you may have an issue with the EATC control head in your Town Car. This is a very common problem with Lincoln TC, Ford Crown Vic and Mercury Grand Marquis vehicles through the 90's and beyond.
If you are mechanically inclined and know how to solder, the problem can usually be easily repaired. The issue is bad solder joints on the EATC control circuit board.
With the engine running and the AC on (Thermostat set to 60*), check for +12V at one terminal of the Cycling Switch connector. Sorry, I don't remember which one but there are only 2.
If you don't see 12V+ at the switch connector, the EATC controller is the likely culprit.
Here's a How To:
Hope this helps.
BTW. If you can't solder or don't feel comfortable opening the module, an Ebay search will turn up folks willing to do it for ~$100. A new Controller is well north of $300 and used ones are a real crapshoot.
Edited: Sat July 14, 2012 at 11:13 PM by newton5
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