2003 Mercury Grand Marquis LSE Heater & A/C motor NOT Blowing


ascorbate
05-25-2007, 01:41 PM
I have read thru another post in this forum about heater and a/c blower motors that stopped working suddenly.

I have a similar problem with a 2003 Mercury Grand Marquis LSE with climate control (Electronic Automatic Temperature Control or EATC for short). I have checked the obvious including the inside passenger compartment fuses plus the power distribution box underneath the front hood with particular attention to both the blower motor relay and blower motor fuses. I even swapped them out with other working relay and fuses in the power distribution box. I then measured the voltage being applied to the blower motor itself under the hood. It read anywhere from 1 to 6 DC volts or so. I have a similar blower motor layout in a well maintained 1997 Ford Crown Victoria (without EATC) and that voltage reading was 13-14 volts whether the fan speed control was set on low or high. So I'm suspicious of the lower voltage I measured in my Grand Marquis versus my Crown Vic... why would there be this big difference?

While traveling down the highway yesterday at 50-60 mph with the a/c set to 70 degrees, I could feel cool air coming from the vents in my 2003 Grand Marquis probably because of some of the air being recirculated from the outside to the inside. The faster I went, the more cool air I could feel coming from the vents BUT still the blower motor wasn't working. So the A/C system is working, it just ain't blowing this cool air around the inside of my car!

I read about a EATC module self test today at: http://www.p71interceptor.com/eatcswap/selftest.html (http://www.p71interceptor.com/eatcswap/selftest.html) which I performed with NO Diagnostic Trouble Codes (DTC) indicated. I then disassembled the fan speed control switch, cleaned it with a cotton swab and some rubbing alcohol, reassembled everything but still the same result... the heater and a/c is not blowing any warm or cold air whatsoever.

What else am I overlooking?

miamibob
05-26-2007, 12:44 PM
The manual suggests (and this is for an older GM but should apply) that you check the leads to the blower motor, fuse for the blower motor, motor itself and the connector at the control head.

You could pull the blower motor and see if the shaft turns when power is applied to it. You may have a "resistor assembly" in the air control box (otherwise known as by the "air blend door"). Usually, though, if that is bad you only get high speed. I would check power to the switch and perhaps replace the fan speed switch as they are cheap enough. As long as you have no "burn outs" or shorts usually the switch goes before anything else! MB

ascorbate
05-26-2007, 02:58 PM
I have read thru another post in this forum about heater and a/c blower motors that stopped working suddenly.

I have a similar problem with a 2003 Mercury Grand Marquis LSE with climate control (Electronic Automatic Temperature Control or EATC for short). I have checked the obvious including the inside passenger compartment fuses plus the power distribution box underneath the front hood with particular attention to both the blower motor relay and blower motor fuses. I even swapped them out with other working relay and fuses in the power distribution box. I then measured the voltage being applied to the blower motor itself under the hood. It read anywhere from 1 to 6 DC volts or so. I have a similar blower motor layout in a well maintained 1997 Ford Crown Victoria (without EATC) and that voltage reading was 13-14 volts whether the fan speed control was set on low or high. So I'm suspicious of the lower voltage I measured in my Grand Marquis versus my Crown Vic... why would there be this big difference?

While traveling down the highway yesterday at 50-60 mph with the a/c set to 70 degrees, I could feel cool air coming from the vents in my 2003 Grand Marquis probably because of some of the air being recirculated from the outside to the inside. The faster I went, the more cool air I could feel coming from the vents BUT still the blower motor wasn't working. So the A/C system is working, it just ain't blowing this cool air around the inside of my car!

I read about a EATC module self test today at: http://www.p71interceptor.com/eatcswap/selftest.html (http://www.p71interceptor.com/eatcswap/selftest.html) which I performed with NO Diagnostic Trouble Codes (DTC) indicated. I then disassembled the fan speed control switch, cleaned it with a cotton swab and some rubbing alcohol, reassembled everything but still the same result... the heater and a/c is not blowing any warm or cold air whatsoever.

What else am I overlooking?

I read in another forum where some Ford tech at a local dealer was replacing tons of Ford basic part # 19E624 which seems to be known as the blower speed controller. I took a chance and purchased one and replaced mine; it fixed the problem and now the A/C will blow your hat off!

Let me tell you though that this was an absolutely "miserable" module to replace. It is under the hood sandwiched below the two heater hoses and underneath the vapor mangement valve and secured with two 8 mm screws. What should have been a 10 minute job turned into a 2-3 hour miserable job thanks (once again) to the forward-thinking engineers at Ford Motor Company. I don't know what those automotive engineers were smoking but it must have been damn good!

I did read somewhere that if this blower speed controller needed replacement, that something else (like the blower motor itself) may have been the real culprit. Anyone else have any opinions about this?

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