QuestionHello. I have 2 issues with my 73 Corvette Stingray. First - I have no functional horn. I tried a new horn, but no go. When I hit the horn, I hear a click coming from a small relay looking item, mounted on the inside of the front left fender well. Is this the horn relay? I am GUESSING it is - and if I try to replace it, I should be in business, but I cant find any reference to it in the manuals that I have.
On a second note - my blower motor doesn't work at all. I am convinced it is not the motor (it doesn't make a peep!). I see references to 2 different blower motor relays, and I wanted to start there. Can you help with locating these? Thanks for your help and time!
AnswerYes, you have correctly identified the horn relay. Since it clicks, it is probably OK. Much more likely, given that your car is a Corvette, is that the horns are not grounded. To prove this, take a piece of electrical wire, 14 gauge or more, and momentarily touch the wire terminal on one of the horns (if you can get to it) or the "H" terminal on the relay, if that's easier (it's the same point, electrically) and put the other end of the wire on the "+" terminal of the battery. This should blow the horns - if it does, I'm wrong, and the grounding is OK. If it doesn't, investigate the wire that grounds the horn - it will be connected to the mounting bracket somewhere, and run to a metal part on the body or chassis that is grounded. You can temporarily run your test wire from the horn mounting bolt to the battery "-" terminal, then try your horn from the driver's seat - that one horn should sound. It will sound funny because you don't have both horns grounded, but it proves where the fault lies- the ground wires.
On the blower motor, you'll have to do some detective work the same way. Don't suspect the relay, which is expensive, until you have proven that the blower motor is OK and that it is grounded. These cars are famous for this sort of problem, due to the lack of a metal body. I know - I drove a 67 for years, and fought all the same problems.
Disconnect the blower motor wires, and temporarily connect them right from the "+" terminal to the "-" terminal of the battery, one wire on each terminal (which one doesn't matter). The blower should run like a champ. Now, connect the ground wire from the blower back to it's previous place (the ground point), and again, put the other wire on the battery "+" terminal. If the blower still runs that way, the ground terminal is OK now,and might stay that way until the next bump. Take it off again and clean the terminal end and the thing it connects to. Now reconnect both blower wires and try it from the control panel. If the blower now works, the problem was the ground wire, which you have "fixed" by fiddling with it. If it doesn't work from the control panel, the problem might be in the switch, or in the wiring. The relay is only involved in the high speed setting, but from what you say, it doesn't run on any speed, so forget the relay, investigate the wires from the switch to the motor, and of course the fuses. With a test light, make sure the heater fuse is good - with the key on, there should be 12 volts at both ends of the fuse, and also on the clips that hold the fuse. If there is 12 volts on one end of the fuse but not the other, the fuse is bad, of course. The tricky thing is the clips that hold the fuse - the fuse can be good but making poor contact, so test the clips also - see if there is 12 volts on both end clips. If not, the problem is a buildup of crud on the fuse clips - a very common problem in an old car that has been east Rockies for part of it's life.
I'm assuming here that your car doesn't have AC - but if it does, the solution is the same, you'll just have to find which fuse works the blower motor - it is probably the AC fuse. Check your owner's manual for that info.
Hopefully, this is helpful. If not, get back to me and I'll try again.
Dick
