Blower motor 3/4 speed tripped/reset c/b... but c/b is 40a

[jackb]

I don't have this meter but from the description it does look like it will read DC current and is not very expensive.

https://www.amazon.com/Meterk-Multim...DHNBF5W380VKMZ

Oh, you mean the clamp style instead of probe style. That’s what I got last night; I didn’t know the exact term for it. I picked one up from Home Depot last night. I’ll be measuring the current draw tonight.

[Bitsyncmaster]

Oh, you mean the clamp style instead of probe style. That’s what I got last night; I didn’t know the exact term for it. I picked one up from Home Depot last night. I’ll be measuring the current draw tonight.

I hope it does DC current. A lot of the cheap ones only work with AC current.

[jackb]

I picked up one that measures DC at Home Depot.
The current draw on each speed is normal...
#1- 2.48
#2- 5.84
#3- 10.59
#4- 13.9

I didn’t run it until the c/b tripped, but it has only happened maybe twice before, ever.
So everything is fine, until the breaker trips for an unknown reason.

I’m going to replace that 40a breaker with a 25a, but that does not solve my mystery problem.
The connections on the breaker look good, but I’m going to replace them with ring terminals as well anyway.

Any ideas?
The problem did fix itself, but I’m at a loss how to isolate the root cause to prevent it from rising up again.

[jackb]

Upon further inspection, I recognized I have 4 wires on my c/b.

The wiring diagram shows only three- one in (live at all times) and two out (one to each fan speed relay).

My car has 4 wires, two on the input, two on the output.
One of the input wires originates from the starter relay. The other three go into the harness. All are brown.

What is the mystery fourth wire for?

[Bitsyncmaster]

I picked up one that measures DC at Home Depot.
The current draw on each speed is normal...
#1- 2.48
#2- 5.84
#3- 10.59
#4- 13.9

I didn’t run it until the c/b tripped, but it has only happened maybe twice before, ever.
So everything is fine, until the breaker trips for an unknown reason.

I’m going to replace that 40a breaker with a 25a, but that does not solve my mystery problem.
The connections on the breaker look good, but I’m going to replace them with ring terminals as well anyway.

Any ideas?
The problem did fix itself, but I’m at a loss how to isolate the root cause to prevent it from rising up again.

Those seem like rally low currents from what I remember testing my blower. Did you check them with the engine running? I will check mine again.

The blower breaker should have 4 wires with the added wire on the "batt" side for the start relay modification. Yes it's a good idea to replace those quick connect terminals with ring terminals.

[jackb]

Those currents were all with the engine idling.
Before those measurements I checked it off battery only and each speed was about 1 amp lower.

[mluder]

Following this as I'm having a similar problem.

A couple years ago I was loosing fan speed 4 and replaced the relay for that (#24). Fixed it great.
Now the entire thing stops regardless of speed. After about two to three minutes it comes back (I can hear the click from the relay compartment). I assumed the speed 3 relay was bad as I think it controls 1-3 and speed 4 is added to it with the second relay.
Anyway, I attempted swapping it with my high beam relay but that didn't fix it.

For the last several months I've been getting some squealing on initial start up of the fan... I assume the bearings are going. It goes away after a few seconds.
Is it possible the increase in friction from bad bearings is causing the fan to draw more power and trip the breaker?

EDIT: Just did a little more research and i see now there's a circuit breaker #19 that controls the blower. I'm thinking that's my issue. Will check it out.

Cheers
Steve

[Bitsyncmaster]

I checked my blower currents putting the current clamp over the blower wire only, at the blower location. Engine was idling and my idle voltage is 14.6 volts. Room temp is 78 deg. F and mode switch on vent.

1 = 3.06 amp
2 = 6.91 amp
3 = 12.8 amp
4 = 17.6 amp

Now technically if the blower motor was hotter the current would go down a little not counting any bearing load changes. I wonder if some blowers have higher current since the recall changed the 25 amp breaker to a 30 amp breaker. Or maybe because the breaker temperature being higher in the closed relay compartment made it trip below the rated current.

[jackb]

My engine voltage is typically just under 13 at idle. If I start it up right now in a not-boiling hot garage (ambient ~85*-90*) I'll get 13 or a hair under. If I'm driving around and its over 100* outside, when I stop at a light I tend to hold the rpm's a little bit because at a true idle it will drop closer to just above the mark between the 8 and 13. My alternator is from DMC-CA replaced in 2011.

[Ron]

What kind of alternator is it?
If it is a GM style and the light comes on when the key is on then goes off once running, a very common reason for low voltage is the pulley is to big. GM basically has 2 sizes, most of which are the larger one. They have a larger drive pulley than Ds...
(It should never get down to 12V, running.)