Blower/Heater circuit breaker tripping

[wngrog]

Man. Maybe a bad breaker even though it’s new? That would be the cheapest try.

 

[red66toy]

Man. Maybe a bad breaker even though it’s new? That would be the cheapest try.

Yeah, I am going to swap it with the other breaker used for the power windows since they seem to the same part number. That would be a crazy thing to be bad but stranger things have happened.
I didn't replace all those parts to chase this issue (thankfully), those were part of a whole HVAC refurbish project since the AC didn't work. I am not sure if this was an issue before since before I fixed the AC it hadn't been run in like 8 years!
However, looking at the old circuit breaker, I am guessing the PO took some frustration out on it

 

[red66toy]

Just checked the compressor clutch. Pulls 3.63 amps when on. That seems to be normal I guess.
So at this point it must be a ground issue (might have to revisit that junction behind the gauges) or a bad CB...
I'll report back with the answer.... hopefully

@beno I'll be giving you a call Monday morning for some assistance with those CBs .... and some other bits

 

[red66toy]

Well..... I swapped the CBs between the heater circuit and the power window circuits to see if the CB was defective. The CB tripped after 13min of the fan being on Hi and the AC on. Seems oddly long. It took about 5-10 before so essentially the same. So then I went hunting for the infamous ground junction behind the gauges:

Ground junction looks perfect to me:

Kind of at a loss for ideas at this point. Anyone have an idea?

 

[wngrog]

Did you replace the amplifier board?

 

[CenTXFJ60]

I’ve been going through the same issue. Changed the fan and still tripped on high. Then did as you and swapped the CB (took one from a donor harness) and it seems to be working. I’m still chasing leaky gremlins so I’m constantly screwing with the system at this point. My truck is converted to a 12HT so the amplifier board is slightly modified. Had to clip one of the connections which I believe had something to do with the tach reading. Will let you know if things change. 20 minutes is about the furthest drive I’ve taken so far.

 

[g-man]

For you newbies out there you can reset your heater CB with a finishing nail. Unplug it an push the nail into the small hole until it clicks. I replaced mine because I thought it was weak but the new CB still tripped when the fan was on high with the AC on. I rewired the fan motor(see my previous post) My motor was drawing over 12 amps on high.

 

[red66toy]

Did you replace the amplifier board?

I have not and that may be the only thing on the whole system I haven't touched yet or suspected. I have been going off of the trials and tribulations of past issues raised in threads.
Is there a specific test in the FSM? I'll hunt for a good used unit to swap and test.

I’ve been going through the same issue. Changed the fan and still tripped on high. Then did as you and swapped the CB (took one from a donor harness) and it seems to be working. I’m still chasing leaky gremlins so I’m constantly screwing with the system at this point. My truck is converted to a 12HT so the amplifier board is slightly modified. Had to clip one of the connections which I believe had something to do with the tach reading. Will let you know if things change. 20 minutes is about the furthest drive I’ve taken so far.

Definitely update this thread when you think you solved it. I am curious, but also this thread should be a valuable resource for people in the future.

 

[red66toy]

Ok, so I cleaned up the common ground point behind the gauges with deoxy electronics cleaner and installed a new-used AC amp board.... still popped. Lasted 25min this time vs the previous 13min. Not sure what the heck that means. I don’t understand why it takes so long to trip.

Argh.

 

[CenTXFJ60]

Ok, so I cleaned up the common ground point behind the gauges with deoxy electronics cleaner and installed a new-used AC amp board.... still popped. Lasted 25min this time vs the previous 13min. Not sure what the heck that means. I don’t understand why it takes so long to trip.

Argh.

I have now run my truck well over an hour with the AC on high and it is holding. I switched back to my original fan (the other one was full of surface rust) and it’s working. So it seems changing the 30 amp fuse (that round thing in the fuse box) helped my situation.

 

[red66toy]

Glad you got it figured out! I think I may still have some corrosion some where on a connection that is heating up over time to cause enough resistance to pop the breaker. Onto the wild goose chase!

 

[red66toy]

Noticed this small tear this evening at the blower motor terminal. I can also see some corrosion in there. Measured 3.8ohms resistance from this terminal to the battery ground. Going to try and get the metal terminal out and rebuild it. Hopefully this helps.

 

[red66toy]

Replaced the terminal and still blowing the CB. Time to move to other areas I guess. I am wondering if I am getting a lot of resistance to ground through the speed switch. I am going to try and yank it out and clean it up. Deeper and deeper down the rabbit hole I go!

 

[Nbndallastx]

Any updates on this AC issue with blowing the CB once on high and AC on? I’m having the exact same issue...

 

[Spook50]

I bought the new one of course.....I don't replace brushes.

Is the 30a breaker an autoparts store part?

Unfortunately no, it's a Toyota specific part. Did you happen to hang on to your old motor? I'm trying to collect junked motors for some experimenting I want to do with restorations and upgrades for more long term service.

 

[wngrog]

I can’t remember 5 hours ago much less 5 years. Sorry man.

 

[red66toy]

I figured my issue out. There was a bad connection in the terminal for the CB in the fuse panel itself that was causing my CB to trip.

 

[Nbndallastx]

Ah ok, nice! Thx for the info!

 

[g-man]

Here's my thread where I struggled with this. A/C blower motor wiring by-pass.
The problem I found was the heater CB was tripping way before 30 amps and I replaced it with a 30 amp inline fuse, no problems since.
this should prob be a sticky in the FAQs

 

[Spook50]

I figured my issue out. There was a bad connection in the terminal for the CB in the fuse panel itself that was causing my CB to trip.

This seems to have fixed my breaker issue as well. Corrosion building up in the connection after 30+ years causing minor arcing and as a result, heat buildup. Cleaned the terminals, reinstalled the breaker and after a 40 drive with everything on max it's still cool to the touch now.