99 ford taurus ecu

I have a 99 ford taurus with 60,000 miles on it and the a/c stopped working.I took the car to mechanic and he said it was the ecu.I changed the ecu with a used one for 80.00.The used one lasted about 3 months and now the a/c is doing the same thing.The a/c compressor runs all the time no matter what the controls are set too.Does Ford or someone make an aftermarket ecu that wont do this or has anyone had this problem?any advise is much appreciated thanks

THE PCM (or ecu as you call it) DOES CONTROL THE A/C COMPRESSOR CLUTCH....TO A DEGREE. BUT THE MAIN CONTROL FOR A 96-99 TAURUS WITH ELECTRONIC CLIMATE CONTROL IS "MAINLY" CONTROLLED BY THE "RCCM" REMOTE CLIMATE CONTROL MODULE. NO ONE MAKES A DIFFERENT PCM TO ANSWER YOUR MAIN QUESTION. I WOULD HAVE YOUR MECHANIC LOOK AT THE RCCM. THIS IS STRAIGHT FROM THE FORD SERVICE MANUAL:
The electronic automatic temperature control (EATC) system is available as an option on Taurus, Sable vehicles.

The EATC uses the integrated control panel (ICP) as the driver's interface to the system. The ICP communicates with the remote climate control (RCC) module via the audio corporate protocol (ACP) communication network. The RCC module controls all of the EATC hardware.

With the use of a microcomputer, the remote climate control module analyzes inputs from the following major sources:

l set temperature, function and blower speed selections (made by the vehicle occupants)

l in-car temperature sensor

l ambient temperature sensor

l A/C sunload sensor (19E663)

THE PART I ALWAYS HATED ABOUT FORDS A/C SYSTEM (on most all Fords) IS THAT EVEN IN THE WINTER, IF YOU USE THE WINDSHIELD "DEFROST" THE A/C COMPRESSOR ACTUALLY KICKS IN, DOESNT MATTER, EVEN IF IT IS ZERO DEGREES OUTSIDE. THERE IS A COMPLETE DIAGNOSTIC PROCESS TO DIAGNOSE THE TAURUS' CLIMATE CONTROL SYSTEM. BUT I WOULD START WITH THE RCC MODULE. YOU CAN ACTUALLY DO A DIAGNOSTIC ROUTINE RIGHT WITH THE CONTROLS OF THE CLIMATE CONTROL BUTTONS. ITS A LENGTHY PROCESS, BUT IT IS WAY TOO LONG TO EVEN TRY TO POST HERE. IF YOU CAN GET A COPY OF THE FORD SERVICE MANUAL FOR ANY 1996 TO 1999 TAURUS'. I THINK ALL 1996-99 ARE ALL THE SAME ON THE CLIMATE CONTROL SYSTEM. I BOUGHT MINE AS AN ORIGINAL FORD SERVICE CD FOR THE PC (same thing Ford Techs use) ON eBay. HOPE THIS AT LEAST STEERS YOU IN THE RIGHT DIRECTION......TONY