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Climate Control A/C Problems

I have a 2003 Lincoln Town Car, that I am having problems with the air conditioning on. It has dual climate control, I have set the temp at 60 degrees and it will not cool until I have driven the car for approx 20 minutes. When the a/c kicks on, it works fine until I turn the car off. When I restart the car, it does this all over again. The freon has been checked and it is fine. Has anyone had this problem? If so, what was your solution? It’s hot in Bama and I need to fix this. Thanks in advance!

First step at least for me would be to check for TSB’s and the get into getting operating specs for the AC system.

The DATC (Dual Automatic Temperature Control) module has many inputs that determines when the AC operates. These are: Ambient Temperature, Cabin Temperature, Sun Ray Temperature, Head Bolt Temperature, and Vehicle Speed.

What needs to be done is, have a scanner connected that can pull body codes for the AC, and see if there’s a problem with one of these sensors, or a problem with the DATC module itself.

Tester

Please note that when set to 60 degrees, it ignores most of those inputs. 60 is a manual max cooling setting, not a true maintain this (60) temperature setting.

It sounds like a bad compressor or a bad expansion valve. Get the operating pressures measured.

The 2003 Lincoln Town Car utilizes a fixed orifice tube/cycling clutch system. No expansion valve. If the operating pressures where low, the low pressure switch would prevent the compressor from operating at all.

Tester

Not if the low pressure side is okay (or even high), but the high pressure side is low.
An orifice is a fixed expansion valve. (Yes, I know that in general automotive terms when someone says expansion valve they usually really mean temperature controlled expansion valve and not fixed orifice expansion valve.)

OK???

Tester

You get a big 10-4 on that one Tester,what is he talking about?

The low side pressure could be okay meaning that the switch would let the compressor run. However that doesn’t mean the high side pressure is correct.
Then again, maybe it’s just stupid to follow the standard diagnostic checks when looking for a problem. After all, compressors never ever fail, especially Ford compressors of this vintage.
But like Tester said, since the compressor is running, there is no need to check anything at all…