Fan only blows on high

my A/C and heating work fine, but the fan only blows it on the highest setting.

What could be the problem and how much will it cost?

The fan speed resistor.

High speed is 12v direct to the motor.
All slower speeds go through a resistor to slow the motor down.
That resistor has a non replaceable thermal breaker ( as opposed to a fuse ) built in.

Only high speed says that breaker is blown, a new resistor is needed…


Why did the breaker blow ?

Is the blower motor old and binding up causing increased load ?
Is there debris in there ?

Simply replacing the resistor may not be the whole story.

I don’t know what year & engine Forester you have but here’s an example from

2002 SUBARU FORESTER 2.5L 2458cc H4 FI (6) [EJ251] : Heat & Air Conditioning : Blower Motor Resistor Price Core Total

$57.99 $0.00 $57.99

very useful… thank you…
the car is old… 1998…
there could very well be junk in there… I suppose getting to the resister (and cleaning necessary things) is the expensive portion of replacing this thing