AC Blower keeps tripping (1 Viewer)

[UGA2018]

Looking for some advice on next steps. My AC fan blower trips the switch on all speeds now. It started only on high speed but now does on all speeds. I pulled the fuse box and felt the wire get hot before it tripped the circuit breaker so I don’t think the circuit breaker is bad. I think it is really getting hot.

I cleaned the air intake as it was full of leaves. Although I got more wind it still tripped the breaker. My #1 speed wasn’t working so I replaced the blower resistor doubting it was it but why not. Still trips.

I replaced the blower motor thinking it has gotten old and drawing too much current but that wasn’t it. it still trips the circuit breaker.

Any thoughts on what to look at next? I can wrench all day but this electrical stuff has me stumped. Thanks!

 

[OSS]

If the fan motor was replaced with a China job since new ones aren't available from Toyota any more - it's still suspect.

Pull the plug at the motor and make a jumper to the terminals to measure DC current with a hand held volt meter. Most meters can handle 10A.
This is what the motor should draw:

LC heater blower fan power amps:
1. 3.3A (low speed)
2. 5A
3. 7A
4. 10A (max speed)

 

[UGA2018]

If the fan motor was replaced with a China job since new ones aren't available from Toyota any more - it's still suspect.

Pull the plug at the motor and make a jumper to the terminals to measure DC current with a hand held volt meter. Most meters can handle 10A.
This is what the motor should draw:

LC heater blower fan power amps:
1. 3.3A (low speed)
2. 5A
3. 7A
4. 10A (max speed)

Thanks @OSS! I’ll give that a go tomorrow and let you know what I found out.

 

[g-man]

I did some work on this a while back and found out that the circuit breaker was weak and not holding anywhere near 30a. Mine was tripping at much less amps. I put a 30a inline fuse in it's place and it's held up.

A/C blower motor wiring by-pass.

I wired a 12 gauge wire with 30 amp inline fuse to the positive battery terminal. (skip to pg 3 post #57 to find the results of this testing and skip a bunch of rambling)

forum.ih8mud.com

 

[John Staton]

Mine would trip on high...I bypassed the OEM fuse with a modern fuse and it has worked ever since. I monitored it at first to make sure the wires did not get hot and it was fine. I might have a few of these laying around if you want to try it. I think I had to buy a 5 pack.

 

[cruiserpilot]

Mine would trip on high...I bypassed the OEM fuse with a modern fuse and it has worked ever since. I monitored it at first to make sure the wires did not get hot and it was fine. I might have a few of these laying around if you want to try it. I think I had to buy a 5 pack.
View attachment 2676401

If you have to go this for a solution, I’d pull the fuse panel completely and do a continuity check to the
blower and check the wiring. Clean it all up.

 

[John Staton]

If you have to go this for a solution, I’d pull the fuse panel completely and do a continuity check to the
blower and check the wiring. Clean it all up.

I did this Sept of 2018, so almost 2.5 years ago and no problems. I just dont think those old style fuses are very reliable. If I had bigger problems the new fuse would have gone bad.

 

[cruiserpilot]

So you still have the ‘jumper’ fuse installed? TBH, I think the fuses are the same.
30 yr old wiring.

 

[John Staton]

So you still have the ‘jumper’ fuse installed? TBH, I think the fuses are the same.
30 yr old wiring.

still installed...mine would only trip on the highest blower setting. The jumper is rated the same (30A, if i remember correctly) as the old so I felt like it was isolating the problem to that old fuse.

 

[cruiserpilot]

Mine tripped on the 3 + 4 positions. Replaced the resistor and cleaned up the wiring it’s as new.
I still have a thin wire taped beside the steering column that I used to reset the breaker through
that little hole. It doesn’t hurt to clean up fuse boxes, they corrode over time and wire gets
chaffed and brittle.

 

[UGA2018]

Thanks for all of the tips. I’m trying to measure the amps with this voltage meter and the numbers just keep going up even when I’m not adjusting the speed. Check out the setting in the picture. It closes the circuit and the fan will kick on but I don’t get a steady reading. Thoughts @OSS ? Thanks!

 

[OSS]

I tested a replacement motor just like you're doing and I got those values I posted above. I don't recall if the Amp reading was a little jittery, but if my Low reading was 3.3A, it couldn't have been jumping around that much.