QuestionI have a 1974 Chevrolet Camaro LT. The A/C compressor works fine but nothing blows out of the vents. I've been told it's a blower motor but I've also been told it's simply a fuse. I replaced the fuse (30 amp) and still no luck.
Any help is appreciated.
Thank you.
AnswerWe need to do a little detective work here, Scott.
First, turn on the key and the blower to the highest setting. Then;
If you have a voltmeter, or a test light, find the two wires that go into the blower motor, then identify the wire that is grounded to the case or some other body part. Then, probe the other wire (find a place where you can get your test lead right on the metal of the wire or the connector nearest to the motor). When the blower should be putting out air, there should be 12 volts on that wire, and the blower should be putting out a strong stream of air.
Now, we can figure out where the problem is:
1. If the 12 volts is present (approximately is close enough, or if the test light lights about as brightly as it does when you test it on the car's battery), the fuse and switch are OK, but if you don't hear the blower running, the motor is definitely bad (or else the ground wire isn't making good contact - so check that visually).
2. If you hear the blower motor running, but still no air moving, the fan squirrel cage is probably loose on the motor shaft - take the blower out and inspect it to see what the problem is. You might only have to tighten up the allen screw.
3. If you don't hear the blower motor running, but the 12 volts is there, either the motor has failed, or something is blocking the fan squirrel cage from turning. This is a pretty common problem, if you have rodents in your area and they like to build nests in secluded places. Take the blower motor and fan assembly out and see what you can clean out of there. You can power the motor directly from the battery - just put 12 volts on one wire, and ground the other to the negative battery post, it should run then.
4. If you don't have 12 volts at the test point, there is something wrong with your wiring, the blower speed switch, or the power feed to the switch from the fuse. Make sure the fuse is good, and making good contact by probing both ends of the fuse holder.
If you don't have a voltmeter or a test light, get one! If you are going to maintain an older car, you have to have one - it will pay for itself on the first job! Go to your local NAPA store and get a good test light - don't buy a cheap one, it will give you wrong answers. Pay the $8 or so for a good one, and don't loan it to your brother-in-law!
Good luck, and let me know what you find out, please.
The blower motors are not that hard to find (NAPA has them) and not that hard to change, if that is what it turns out to be.
Dick
