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Why does the heater fuse keep blowing?

10K views 9 replies 6 participants last post by  CopperFiremist 
#1 ·
My mom went out and started her 98 Astro the other morning and absolutely no air would blow from the vents...found a blown heater fuse. I replaced the fuse and all was well for a couple days. Went out again this morning and again, no air coming from the vents. Put a new fuse in and it started blowing. I turned the fan switch all the way down, and when I turned it back up, it blew the fuse. Now every time i turn the fan switch down then back up, the fuse blows, but only when I turn it back up. The heater switch has only worked on low and medium since she got the van 4 years ago, but that was good enough for her so we never messed with it. Now that its getting cold out, I REALLY need to figure out why this fuse is blowing. She needs to have heat in the van because she always has at least one grand child with her. Any help would be greatly appreciated. This van has a/c if that matters. Thank you in advance.
 
#2 ·
Start out by opening the hood, and looking at the heater box. There is a gizzy there that is part of the wiring for the fan called the resistor pack. Look at the connector and see if it looks like it has

been hot. There is a good possibility that you need to change out the fan motor, the resistor pack, and the connector. Trace the wire that connects to the fan, back to the next connector on the

heater box. You may have to remove the cooling system overflow tank, and the w/s washer fluid tank to get a better view.

Bob
 
#3 ·
Very likely you will need to replace the fan motor , when they get old and worn they begin to draw too much current and cause problems , it be possible your fan switch has a short in it , when you inspect the resistor plug you will likely see some signs of wires overheating the red one is for high speed , that will also indicate the need to replace the fan blower and replace the connector plug
 
#4 ·
The connector looks fine...doesn't look as though its been too hot. Should I just change the blower motor? I've been told by a couple people that its the blower motor drawing too many amps, and others have told me to change the switch because it was not working properly before...I'm very limited on funds and looking to find the cheapest fix. I appreciate the quick response
 
#5 ·
The blower motor can be had at Advance auto for about 25 dollars with lifetime warranty , considering that a resistor will cost more than 40 dollars and the reason they go bad is when the motor gets old it will draw too many amps , so since you do have low speeds working , you can protect your resistor by replacing the motor with new m that way you have caught it in time before it blows the resistor . , you should be testing for voltage at each of the wires on the resistor plug to make sure there is 12 volts at each wire , you can use a test light , if you have power at each wire terminal color , you can then test the switch , For me since this is a common age wear problem , and the resistor costs more than the motor and it is the motor that causes the resistor to blow , I would change it just to be sure , winter is coming and you need to be sure it all works right , there is also another plug behind the battery that gets the red wired burn problem , a gray plug with 5 wires
 
#8 ·
Tommy99 said:
be glad fuse is blowing my fan sw just went up in smoke, wife thought van was going to burn up does anyone know if this is typical when they go
Not typical ,, quite unusual actually , there must have been something unusual causing a short in it or someone may have put a too high amperage fuse for that circuit in the fuse box ,that the reason why there are fuses , so they blow and not the circuit or wiring . Sometimes people will put any fuse or stretch wire across just to get voltage flowing ,, not a good idea as that can cause fire , go through your fuse boxes and make sure the correct fuse are in them
 
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