2000 Mercury Villager Q&A

2000 Mercury Villager Question: Front AC/Heater Fan speed resistor keeps failing every 8-9 months.

The fan speed resistor for my front A/C - Heater keeps failing. Part only seems to last about 8-9 months before it burns out (then only high speed works). Any ideas why? -
Answer 1
Get specs and test other parts in the circuit for improper resistance. Possibly blower motor pulling to much current. -
Comment 1
Agree with 1 resistance is also a bad connection anywhere in the circuit. Check connector's for signs of high heat ie melted conn.plastic,blackened metal terminals. Repair connector kit avail. -
Comment 2
Thanks all! Good advice, although where can I find the specs for the Fan blower motor circuit? My repair manual only provides a wiring diagram and fuse rating. BTW, I did check wiring for evidence of over heating. All looks OK, but the failed resistor boards do show signs of overheating (excessive current draw?). Would a low voltage condition cause the problem? My alternator is orignal (156K miles), but I do not have a starting problem or low battery issue. -
Comment 3
Check all grounds carefully & if in doubt clean/repair as necessary.Are you using an ohmmeter or just visual inspection? -
Comment 4
I have an ohm meter, but i do not know what resistance is acceptable. -
Comment 5
I have an ohm meter, but i do not know what resistance is acceptable. -
Comment 6
For any ground circuit -as close to zero as possible. Also just thought of something else-- is there any damage to the heater box that would restrict or block airflow past the resistor? -
Comment 7
No damage or blockage that I can see. I'll check the wiring when I replace the resistor board. Thanks for your help! -