My heater fan only blows when it is set to 4. On 1, 2, and 3 it doesn't do anything other than what wafts in from the forward movment of the vehicle. Fan switch? Resistor in the box?

 

Im pretty sure it's the blower motor resistor which is behind the glove box.

 

Either the resistor or the relay.

Im 90% sure when on 4 it bypasses the relay. But I could be confusing it with the resistor.

 

Well mine is the resistor and it only works on 4. 1 you can't really tell because it is so little so the 1 might work too.

 

X2^^ Had that happen to myself, and it was the blower motor resistor... Quite confident it would be that. Shouldn't be too expensive for you either.

 

My guess is the fan blower switch. Mine only blows on high. Autozone has em for like $15

 

Sounds like a bad resister to me...

 

I Just had the same problem on my MJ earlier this week, blower motor resistor took care of it. $23.99 at Advance Auto

 

It IS the resistor! Get a new one. The resister changes the voltage to the blower fan depending on what speed position the switch is in. If there is no voltage drop due to a "resistor" in the circuit then it will only blow on HI or 4.

The fan speed has NOTHING to do with the relay.

If it were the switch it would either work or not work, or be intermittent. Not only blowing on 1 speed.

Not trying to be a dick head. But people just shouting out answers not knowing what they are talking about really shouldn't even post because it causes the OP confusion and possibly wasted time and money buying parts they didn't need.

 

Thanks for the replies. How do I get at the resistor? From under the dash or under the hood? Thanks again.

 

ON my 88 its under the dash, right side. Not sure about all years.

 

Mine was doing the same thing. On my 2001 it was under the dash on the right side also. my replacement and bad one looked something like this.

 

I say again.

 

Here is a photo of it, the white thing is the BMR:

 

43 bucks? Damn. Is it worth my time and effort to grab 2 or 3 out of the junkyard?