95 Sonoma 4.3-bad blower

My blower quit several months ago and I've just been living with it but now want to get it fixed b/f summer gets here. Before it finally died, it blew on only one speed (high---the dash switch no longer regulated the speed) and made a loud, roaring sort of noise. Anyhow, I got out my old Haynes (like Chilton) manual and started reading up on replacement. It said to first check by hooking the battery directly to the power plug for the motor to make sure it wasn't a resistor problem. Did so, and when I manipulated the dash switch I got a clicking noise (like a relay) but no blower. What I'm wondering is this an indication that the problem is actually the resistor and not the motor?

Did the blower work when you applied battery voltage directly to the blower motor? If so, check the high blower relay and the resistor. All blower speeds go through the high blower relay.

Welcome to AF on your first post.
If you are getting a clicking noise like a relay you are not feeding it direct battery power.
Feed the blower some 12 volt battery power from battery positive to a 30 amp fuse or circuit breaker and straight to blower motor.
If the blower motor runs then it is not blower motor.

No, voltage directly to the motor did not make it run.

No, voltage directly to the motor did not make it run.

If you put 12 volts to it and it has a good ground the blower motor and does not run it is bad.
But Always check the ground/wire on it to.
The motor grounds threw the case with a ground wire on the side of blower motor case.
Hook a test light to battery ground and see if it lights up on the blower motor case when you have 12 volts on blower motor hot/positive feed plug in.
MT

thanks for all the helpful responses. ended up being the motor. I replaced, but in the course of doing so, I noticed that only one of my AC/blower relays (the middle one) was working. Since b/f the blower quit, I only had high speed on the blower, I made the connection that the other two speeds might be connected to the other 2 relays? So I replaced them too. But once I did that and installed the motor I still only have high speed like before. Any ideas?

There is only one blower relay. Check the fuses first, if the fuses are good, check the dark blue wire for power on the 3 low speeds at the relay with the key ON. If not ok, then check the blower resistor, remove it and inspect the coils inside it for damage.

the fuses in the fuse block inside the driver's side door are good, if those are the ones you mean (are there any others?).

My Haynes manual (like a Chilton manual, I believe), says that all three of the relays hanging from the firewall (to the right of the resistor you mentioned, I believe) are all A/C/blower relays; this is incorrect? If so, what are the other 2 for? I checked them all and only the middle one clicked when I manipulated the blower switch, so as I said, I replaced the other two. Like I said, I installed a new motor, which is working, but only blowing one speed, which I believe is high. From my earlier questions, it seems to me the motor wouldn't work at all if the resistor was bad?

There are 3 resistors in the resistor pack. At the resistor there are 4 wires: Brown is hot when low speed is selected. Current goes through 3 resistors. Tan is hot in med 1 speed and current goes through 2 resistors. Light blue is hot in med 2 speed and current goes through 1 resistor. All current for the first 3 speeds goes to the relay through the dark blue wire. That current goes through one set of contacts in the blower relay, (dark blue wire to the purple wire). One of the orange wires at the relay is hot at all times. When high speed is selected, the second orange wire also becomes hot. The second orange wire trips the relay and it connects the purple wire to the hot at all times orange wire. Black goes to ground, and purple goes to the blower motor.

Depending on what was wrong with the resistor, it could inhibit just low, low and med 1, or all 3 low speeds. The resistor is bypassed in high speed.

Old Master/MT-y'all have been great. finally got around to taking out the resistor and looking at the coils. it looks fine to me (no corrosion, rust, etc., except a little rust where the coils are soldered to the plate where the plug terminals are---looks insignificant to me but as you've probably been able to tell by now I am no expert)---as a matter of fact the coils still look practically brand new.

So to review, I have circulation now but only on high speed. Do you think I need a new resistor or is this a heat/ac controller/dash switch problem?

Unplug the blower relay, check the resistance of the black wire to ground, should be close to zero ohms. With the key in the OFF position, there should be voltage on only one orange wire at the blower relay plug. With the key in the RUN position and the blower switch not in the high speed position, there should only be voltage on that same orange wire. Select high blower speed and both orange wires should have voltage. Plug the relay back in.

Unplug the resistor, turn the key to the RUN position, use a voltmeter and check for voltage at each of the wires at the resistor plug described in post #9. If voltage is ok on each of the wires, the switch, wire harness and fuse are ok. Connect the resistor and check for voltage on the dark blue wire, (at the resistor plug) in low, med 1 and med 2 blower speeds. If voltage is ok on all 3 speeds, the resistor is ok. Check for voltage on the dark blue wire at the high blower relay, for each of the 3 low speeds. If you have voltage on the dark blue wire on all 3 speeds, and the blower does not operate, the relay is faulty. If you follow these steps, in this order, you will have checked the entire heater blower circuit for all speeds. Post your results, and we can pinpoint the problem, unless you'd rather just install parts until it's fixed ;)