Scandcar Volvo parts shop

How to fix a 740 940 heater motor resistor

A very common problem of the 740, 760, 780, 940 and 960 is the blower motor that’s acting weird. In some cases it stops working, but a very common problem is the heater fan is only working at the highest speed and doesn’t respond at all when the switch of the blower is in all other positions. Tired of it? This repair manual will help you to fix the blower motor of your Volvo 740 or 940.

In the Volvo 200-series the blower motor was build in a case which was installed in the middle of the dashboard (behind the center console), and when it’s broken the entire dashboard must be disassembled. It took several hours to replace the heater motor and/or resistor. Fortunately Volvo changed the layout at the Volvo 700-series (the blower motor was moved to the passenger side of the car, just behind the glovebox), resulting in a much easier way to access the heater motor and resistor for the blower. Instead of taking hours you’ll reach the resistor and blower in just a few minutes!

Replacing the resistor of the blower of your Volvo 740 or 940

With this step-by-step tutorial (for cars without airconditioning) Volvotips will help you replacing the resistor of the heater motor. Recognising the problem with the resistor of your Volvo 740, 760, 780, 940 or 960 is pretty easy: the heater fan only works at the highest speed. Replacing the resistor is pretty easy and not very expensive. Be aware the old type resistors (used until 1991, Volvo part number 1391789) are hard to get, so you should check if it can be fixed (ask someone who’s handy with electrics if you don’t have a clue) or try a used one. Skandix are selling special cable harnesses which replaces the old version and you can install the new type heater motor resistor. Your local Volvo-dealer should also have these special cables (or build one yourself if you’re a handyman with electrics), it has Volvo part number 9139700 and the resistor has Volvo part number 3522313 or 9171002 which also can be bought at VOMD).

Please note: this tutorial is for the Volvo 740 and 940 without airconditioning (and for cars with aftermarket airco-systems). The how-to below can also be used for cars with airconditioner or ECC but might be slightly different. Enjoy the step-by-step tutorial below for having a nice working blower motor again in your Volvo 740 or 940!

Click on the images for a larger version (will open in a new window/tab).

Step 1: remove the plastic panel under the glovebox

It’s pretty easy to remove it: just turn the 3 plastic screws (with a flathead screwdriver) about a quarter and remove the panel.

Volvo 740 760 780 panel under glovebox how-to replace blower
There are 3 plastic screws/toothed clamps, be sure you don’t break them

Volvo 740 760 780 940 960 panel under glovebox removal replacing repairing blower motor
The panel is now removed

Volvo 740 940 heater fan blower motor housing cables
This is where we’re looking for, but a few steps must be taken to enter the blower motor and resistor 

Step 2: removing the glovebox of a Volvo 740 or 940

In the next steps I’ll show you how to remove the glovebox of your Volvo 700-series or 900-series car. You’ll need a Phillips screwdriver and a wrench or socket of 10mm.

Volvo 740 760 780 940 how to remove dashboard glovebox to fix blower resistor
You’ll need to remove the 10mm nut with a wrench or socket. This picture was taken before I removed the panel below the glovebox 

Volvo 740 940 glovebox cover screw remove repair blower heater motor fan
Open the glovebox and you’ll see on the left and right sides these covers. Behind them are Phillips screws 

Volvo 740 760 940 960 how to remove glovebox blower fix tutorial
Remove the covers gently (otherwise they’ll break) with a flathead screwdriver. Remove the screws with a Phillips screwdriver

Volvo 740 760 780 940 960 heater blower radiator interior
Job done! The tube on the right is the housing of the blower motor. In the middle you’ll see the resistor (with a cable on it) and on the left is the heater radiator in its housing. Now it’s time to focus on the troubles of the heater or resistor

Step 3: removing the blower motor resistor of your Volvo 740 or 940

In this step we’re reaching the problem why your Volvo doesn’t have a perfect working heatermotor (it only works at the highest speed and we don’t want a hurricane in our car): the resistor of the heatermotor.

Volvo 740 760 940 heater fan blower motor resistor troubleshooting guide
There it is: the resistor of the heatermotor (aka blower). You can easily remove it with a Phillips screwdriver. Take it out carefully by pulling it slanted from the left side to you

Volvo 740 940 old type heater fan blower motor resistor troubleshooting guide
The resistor of your Volvo 740 blower motor. Replace it or refurbish the current resistor

Step 4: replace it, reinstall everything and job done!

When you replaced the resistor, it’s time to reinstall everything by taking all steps backwards. When it’s done: test if the blower motor is working in all positions. It’s working fine? Congratulations! You have successfully completed this repair manual!

Any questions or comments? Feel free to e-mail me at info@volvotips.com

 

© Volvotips 2012

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