Blower motor - resistors
Kristamarie
11-14-2007, 07:23 AM
Will bad resistors cause the heater fuse to keep blowing? I just replaced:banghead: the fan and the relay, but the fuse keeps blowing.
The fan will blow then stop, and when I pull the fuse prior to it blowing...it is already getting hot. I can hear everything else working (ie...the vents moving and the unit engaging, but no fan).
The fan will blow then stop, and when I pull the fuse prior to it blowing...it is already getting hot. I can hear everything else working (ie...the vents moving and the unit engaging, but no fan).
LMP
11-15-2007, 07:55 AM
www.avigex.ca/xport/hvac_diagram_front.jpg
On HIGH, the fuse is not used: feed is through the relay, direct from fusible link connected at starter...so in this position, the fuse should not carry any heavy current: just the relay coil current, less than 1 amp.....
ON other lower positions, current is limited through the resistors..so current should be at a safe level unless there is a short in that resistor pack that makes the heater blower try to run full speed at lower setting and then draw 25 amps though the fuse.
....is your fuse rated 25 amps as it should?
Notice rear blower is fed through same fuse, so make sure this one if OFF...its current adds up with the front blower lower settings; a problem with rear blower cmight have to be investigated too if fuse blows only when the two are working.
On HIGH, the fuse is not used: feed is through the relay, direct from fusible link connected at starter...so in this position, the fuse should not carry any heavy current: just the relay coil current, less than 1 amp.....
ON other lower positions, current is limited through the resistors..so current should be at a safe level unless there is a short in that resistor pack that makes the heater blower try to run full speed at lower setting and then draw 25 amps though the fuse.
....is your fuse rated 25 amps as it should?
Notice rear blower is fed through same fuse, so make sure this one if OFF...its current adds up with the front blower lower settings; a problem with rear blower cmight have to be investigated too if fuse blows only when the two are working.
Kristamarie
11-15-2007, 10:07 AM
The rear blower hasn't worked in about two years...so it is always off!!!! Just started having these conditions. The fuse does not pop until after the system has been on for a while, so I am pretty confident that it IS NOT a short. I have a box of 25 amp fuses and I will have to check to see if it only pops on high or low...or I can spend $25 bucks and buy a new resistor pack and check it that way.
Automotive Network, Inc., Copyright ©2026