When you’re driving in the heat of summer, have you ever had your AC cabin fan suddenly stop working? Usually it’s speeds 3 and 4 that stop - 1 and 2 keep working just fine. After a few minutes at speeds 1 or 2, 3 and 4 will magically start working again and the cycle repeats itself. What’s going on?
Fan speeds 3 and 4 are controlled by a single 25A circuit breaker in the relay compartment behind the passenger seat. This circuit breaker can get tripped due to high resistance along the fan speed 3 and 4 circuit - simply replacing the circuit breaker alone will not fix the issue if the area of high resistance is still present. Areas of concern to check include:
Condition of the cabin fan - does it squeal or rattle when running? Has your AC box ever been clogged with debris and not draining properly, causing water to backflow into the cabin fan motor? This can cause rust to develop in the internal components of the cabin fan, which leads to high resistance. Also check the conditions of the wire terminals at the cabin fan and make sure they are secure and making a clean connection. Sold with and without a squirrel cage, a new cabin fan can be found under part # 101273A (with cage) and 101273B (without cage).
Condition of the cabin fan speed resistor - like the cabin fan, the portions of the resistor that sit inside the AC box can become corroded over time due to moisture and will cause higher than normal resistance. The coils of the resistor can also get covered with debris that has fallen into the AC box, such as dead leaves, and we’ve even seen rodent nests built inside this area of the AC box! If the resistor is in need of replacement, it can be found under part # 101275.
Condition of the fan speed resistor connector - what do the terminals for the car’s connector look like? Are they corroded or tarnished? Is the whole connector melted or warped in shape from any heat buildup due to excessive resistance? Does it have a strong connection to the terminals on the fan speed resistor when you plug it in? If not, a new wiring pigtail is available that can be spliced in - part # 101275A.
Condition of the wire terminals at the circuit breaker itself - the 25A circuit breaker for fan speeds 3 and 4 can be found mounted vertically in a clip on the bottom right corner of the relay compartment mounting tray, next to the 40A circuit breaker for the radiator fans. The 25A circuit breaker should have either three or four wires plugged into it depending on whether or not a starter wire mod has been performed (part # 114017 is what you need if it hasn’t - and this is something that every car needs!). What condition are the wire terminals in? Are they corroded or fitting loosely on the circuit breaker tabs? Is the wire leading up to each terminal flexible and with solid insulation that isn’t cracking or showing signs of overheating? A fine-grit sandpaper can be used to remove any corrosion or discoloration on the tabs, and the terminals can be gently crimped so they have tighter engagement with the tabs when installed. If you cannot achieve tighter engagement, you will need to replace the terminals.