1988 mercury grand marquis, my A/C hi/low speed control is not working. It kn blows air when I have it in HIGH but if it gets to cold and I want to turn it down just one notch it'll turn off. Can anybody help me out with this problem?.If so, what part/s will I need to change?
Mercury had 2 systems in the Grand Marquis, the ATC system and the standard. What one do you have?
I have no idea :/
OK look at the temp control lever if it has numbers on the scale then it is an ATC unit, if it has only a scale that goes from blue to white to red then it is a standard.
If your system is standard there is a resistor block under the hood fairly close to the blower motor, it will be held in by 2 small screws and might be a faded red color if it hasn't been replaced before. It is available at most parts stores. If it is a ATC unit the fan is controlled by a small mode control unit kinda like a computer, if that needs work I would suggest taking it to someone you trust in an auto repair shop.
I second the blower motor resistor block, under the hood. The HI setting is the normal blower speed, so HI will always have juice. The resistor gives you MID and LO speeds. Its right behind the intake plenum, screwed on to the heater box. Its straight forward to replace but, its in a tight spot.
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