Repairing HVAC Fan Motor Resistors / Blower Motors

HVAC Fan Motor Resistors

HVAC Fan Motor resistors are responsible for controlling the blower motor speed. They do this by varying the voltage supplied to the blower motor. They are prone to shorts, corrosion, and overheating. When the resistor fails, typically, the highest setting is the only option that still functions. 

When replacing your heat, A/C, & ventilation blower fan motor or HVAC van motor, we always replace the resistor. We do this due to the potential that the old resistor may damage the new motor. We also replace the inexpensive relay just to ensure that you HVAC motor will not prematurely fail and that you’ll always have air flow though your HVAC system.

Some Blower motors look like this and need assembled inside the blower motor housing.

Other fan motors, mostly on modern cars, come like this ready to install.

Another reason your fan motor might not be working is the switch on your dash. Although very unlikely, we have seen these fail on some cars. Vehicles with more modern digital temperature controls are a little more complex. These digital controllers are also known to fail, however diagnosing the problem is sometimes a little easier. Using a OBDII factory scan tool, we are able to scan the entire vehicle for fault codes. The HVAC system will typically tell us what to look at, although it never says, “replace this part”. We would have to manually inspect the components related to the fault codes and identity the exact problem.

Sometimes performing a service on your air conditioning system will fix the problem. Systems that have leaks and are low on refrigerant will not function. Other times too much pressure will cause it not to work as well. One thing we see a lot of is people trying to charge their own A/C systems with a over the counter bottle. This is by far the best way to damage your A/C system. We see more damage to A/C systems cause from owners thinking they can fix it with a bottle for $25. In the long run you might pay hundreds, if not thousands of dollars to repair this. Over pressurizing the system will damage sensors, pumps and expansion valves. Bring it to the professional with the correct A/C service machine and avoid costly repairs in the future.

For more information on how to get your European cars HVAC, A/C or Fan motor repaired in Renton, call 425-254-0627. You can also email us by clicking here. Meister Werks European & Import is located one block south from The Renton Landing in Renton, WA, across the street from the former Boeing Store and on the westside of the Paccar / Kenworth plant.