THe blower motor stopped running a few days ago, it was running fine, no noises and then it just didn't turn on the next time i went to use the heater. The blower motor is fine, I ran a power wire from the battery to the motor and it whirred away. My next test is on the thermostat switch. Does anyone have an idea of where this thing is located in a 1976 Electra? I don't know what it looks like, and the shop manual doesn't say anything about where it is. Thanks alot friends.
Actually I need to find the blower switch and the engine thermo-switch, as stated in the shop manual. An ideas?
Well, I think Schucks have the part, but I didn't specify. I'm looking for the location in the car. I looked around on the engine side and under the dash but I didn't see anyhting I thought would be a switch. Anyone know? It's a 1976 Electra. Thanks
Are you refering to the relay? The switch in the dash should be wired to a small box on the firewall. That way the high power doesn't go to the dash. Try following the wires from the blower motor plug.
Nah, the shop manual calls it the engine-thermo switch and the blower switch. The realy is somewhere around there too. The blower motor is on the engine side so it's easy to get too. I pulled the temperature controls out and looked around on them but I don't think the switches were there, I think they might be on the right side of the car. I'll have to take a peek into the wiring diagrams.
You can try calling a local parts store and asking them - doesn't mean you have to buy it from them. An electronic "switch" can be many things - anything that turns something on or off, or helps turn something on or off (like a relay, thermistor, reed switch, thermostat (like in your house, not the one in the engine), etc). I doubt the manual is refering to something you can physically flip or push. It could be a sensor that screws into the intake, though I doubt it for the heater blower. I'd still follow the wires. If you can find the correct relay, you can trace the wires from that too. If its not the relay, its probably wired too it.
Anyone know if this thing comes apart and how? The Buick shop manual says nothing about this unit. Its for the automatic temperature control froma 1976 Electra.
I located the low blower relay. My wiring diagram shows it and the automatic relay together. They are both bolted to the firewall. Howcome there isn't a high blower relay? Could this low blower relay be my culprit? How would I go about checking it?
I'm not sure about the high/low thing. I thought one relay did it all. Also, I'm going on general knowledge here as I've a 70 Skylark. I'd think a 76 would be similar enough, though - I can't think of any major tech changes until the 80s. If you could find a diagram showing what blades on the relay do what, you could test it by removing the relay, and applying voltage to the correct blades. This way you're using a wire (or screwdriver) to act as a switch, and you should hear a "click" when the relay activates. The best way would be to use a test light when you do it - as it may be too quiet to hear. You could take the relay to a local auto store and see if they can test it - but you'll have to trust they aren't just trying to sell you one (not that they're that expensive). Oh, have you checked the fuses? There should be one in the passenger compartment, and sometimes there is a fuse in-line with one of the wires on the engine side (will probably be a rubber covering in the middle of a wire somewhere). Also, on the housing for the blower motor you should fine a plastic plate that can unscrew. Follow the wires from the relay. It should have a few resistors (they may look like stiff springs). If one of those is shorted or broken in may cause part of your problem. However - if a resistor is burnt out, I'd look around for a short in the wiring before replacing them, or it may happen all over again. Hope this helps.
Ill check again tomorrow evening and update. When I was looking at it today, I noticed something inline with the climate control brain which controls the vacuum routing and heating/cooling temperature. I noticed a plastic shroud that looked like it had scorch marks around it. This may be another fuse although I though the only fuse it was connected to was in the fusebox by my feet. Thanks for the help Truzi
Sure, no problem. All this time I've been hoping someone with more knowledge would chime in - but we should be able to get it eventually.
One thing that often go wrong on the mid-seventies ACC units is the 30 amps inline fuse. I had problems with both my former 76 and my actual 75 as they burned them often. The fuse overheats and burns. I don't know for sure what causes this condition but it looks like there is resistance in the fuse holder itself, between the fuse and the copper contacts... That causes the fuses to burn the hidden part of the metal strip, so it looks good when you look at it through the glass... The fuse is located inside a plastic housing on a big red wire, near the a/c programmer. It's a pain to replace on the cars that are equipped with air bags but quite easy on the others. As you say, it could be the thermostatic switch behind the passenger side head too, but if I remember well, the blower would still work on the defrost position as it bypasses the switch... The blower relay is another possible cause but I'd check the fuse first!
The problem was fixed. I found the fuse last night and replaced it. If it keeps doing it though, that may be from a short somewhere. But for now I won't worry about it, I have heat. That in car switch with the hose and 4 wire plug would be hard to find a new one. That looks like a special part.
The cars with the automatic climate control have a problem with that fuse getting hot, then starting underhood fires. There may be a couple of causes. The high blower relay may stick open and heat up the fuse, or the blower motor may be worn enough to heat up the wiring, but not trip the fuse. I saw a bunch of Cadilllacs in the wrecking yard that burned due to that relay/fuse.
On this car, it has no high blower relay, it has an auto matic blower relay which I believe controls all other settings other than low. It allows the ACC to do the auto part and heats and cools as necessary, I will definately keep an eye on it. THe plastic shroud that encases the fuse looked like it had a scorch mark on it and I knew at first glance that te fuse was blown, it was pretty blown.
Uhh oh, now the heater isn't blowing really hot air like it used to. It's like luke warm. For this to all of a sudden happen what could be wrong? I don't think it would be radiator cap or coolant levels just because I haven't noticed any leaking.
The heater core could be clogged. It happened to me on my 75 and on other cars. Sometimes it happens suddenly! With the blower running and the engine warmed up, touch both heater hoses near the heater core to see if the return hose is much cooler, it would confirm that the heater core is clogged, Some cars have water valves that do not allow the coolant to run in the heater core if it is defective or it gets no vacuum but this is unlikely to happen on the mid-seventies cars since the water valves closes with vacuum applied instead of opening like it was on 60's cars. As I think about it, 76's (at least those with ACC) did't have water valves, that's the only difference I know in the ACC system between 75 and 76 models.
Check the coolant level first - just to be sure. Always check the simple things first. Do not open the radiator cap if the engine was running even for a few minutes. I did that once, and it shot coolant about 20 feet. If its okay, with the car hot, feel the top radiator hose to make sure its getting hot (thermostat is opening). Make sure the heater is on, and feel the heater hoses - one should be hot if the valve is opening. The valve should be in the ingoing heater hose, and should have a vacuum hose attached to it. Make sure the hoses are connected and in good shape. You might have simply dislodged a vacuum connection when you were doing the other things. Then, go in the car, but with the fan off (or car off) move the lever for the heater control from one end to the other - a cable will cause a door in a fiberglass box to open and close. You won't see it, but if its quiet, you should be able to hear it. If the door won't move, the heat won't get into the passenger compartment. Now, if all these things check out fine, the heater core may be clogged. Keep an eye on this thread too, not everyone replies to all the similar posts, so you might get additional info.
