Blower fan/relay
- Thread starter 84chevguy
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Wallace6
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Do you have any ideas which wires I can cross to see if it turns on , I have a feeling that it's the relay in my 1st picture bottom relay. It's cheap enough but would be nice to somehow test it. Thanks. Also my purple wire goes to nothing and didn't before, while it worked. I really need my blower motor working this time of year LoL
Bextreme04
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Unplug the wire to the blower motor. Use a mutimeter or a dummy light and with the ignition switch on, see if you have power at the blower motor. If yes, replace the blower motor. If no, move over to the relay. If you are getting power going into the relay, but not out then it is a bad relay. If you are getting no power in or out of the relay its most likely a bad fan switch or a broken wire/bad fuse.
Wallace6
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Thanks for the reply,I have rear a/c and at one point rear heat, that has been removed. There are so many wire's in that area. Like I said my purple wire goes nowhere and it worked like that before. Honestly I don't wanna rip the a/c under hood plastic plenum apart,when it was working fine a few months back.
If I just knew which wire to jump straight from the battery to make sure the blower still works.
Thank you
If I just knew which wire to jump straight from the battery to make sure the blower still works.
Thank you
Ricko1966
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1 point missed a relay needs 2 powers 1 ground and has 1 output. So yes check for power to the motor . Check for power to the relay,but for the relay to close it needs either a switched power or a switched ground to pull the points closed. I don’t have time to look for a wiring diagram. If you find one and post it I'll tell you what to check. But it really is simple. If you can find the hot in and the hot out then the other 2 are another power and ground but switched. When there is power and ground the relay closes.Supply a power and ground to those 2 if the relay closes its good,you can do this on a bench with a battery charger. Edit. I just reread your original post you can close the points and the fan runs. So the entire problem is on the low power side of the relay. Either the low power side has no power,no ground or the coil in the relay is open. Put 12v to the low power side of the relay,see if the points close.
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RanchWelder
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Hard wire your blower directly to the battery.
Fuse it.
Use a real quality 12v switch and a new heater blower resistor unit... 3 different wires on the circuit connector...
Replace the dssh switch if it's bad. Consider a 12v on/off switch instead of the three way or buy a 3-way for a Peterbuilt and never go back.
If you add a Zenor Diode and a normal regulator diode as a fly-back circuit protection, with a 5 pin relay, durig th restoration process, and a 12v fuse, (at the recommended fuse rating), you will have dash gauges issues ever again.
...and what do I know?
Just take my last paragraph apart, line by line and search for the solution... for the things you do not know?
Fuse it.
Use a real quality 12v switch and a new heater blower resistor unit... 3 different wires on the circuit connector...
Replace the dssh switch if it's bad. Consider a 12v on/off switch instead of the three way or buy a 3-way for a Peterbuilt and never go back.
If you add a Zenor Diode and a normal regulator diode as a fly-back circuit protection, with a 5 pin relay, durig th restoration process, and a 12v fuse, (at the recommended fuse rating), you will have dash gauges issues ever again.
...and what do I know?
Just take my last paragraph apart, line by line and search for the solution... for the things you do not know?
Wallace6
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I will try all of the above and thank you. Is there a simple way to run a wire from the hot side of the battery to a single wire and make sure the blower spins. Thanks again
Bextreme04
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I can't find where he ever said that. He has been asking us which wire he needs to jump to the battery to do that.
Bottom line, the blower motor should always be on. That relay does not "turn on" the blower motor. It switches the power from the resistor lines that vary the fan speed to a direct connection to the fuse box in order to run the blower at high speed. I had an issue where my blower motor wouldn't work at all some times and would screech and work at slower speed other times. It turned out to be the relay going bad and the internal contacts were corroded and making poor or no contact internally. For you to have NO blower activity in ANY fan speed setting, you would have to have either no power to the circuit at all, a bad relay, or a bad blower motor. A bad ground on the relay switching side would only keep it from going into high speed. There are no other grounds in the entire system.
Ricko1966
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At the bottom of post 1 he said he closed the points manually and the blower came on. I past track of it also,after all the running new wires,regrouping the motor etc.. his blowers good he has power to the main lead on the relay,only thing I can figure is he has a bad switch or no power to the switch.
Bextreme04
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Does the fan come on when you turn the fan switch to HI? That's all the way up. The fan switch will send the power signal through the blower motor resistors for the first three speeds of the fan and then through the relaxed state of the relay. The high speed setting switches the relay on and makes a direct connection between the fan and battery feed.
So, if you have no power to the blower in any fan setting, you likely have a problem in the fan speed switch or blower motor resistor circuit. You need to get a mutimeter or test light and actually check these circuits in order to know which one for sure.
Bextreme04
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Oh, yep you are right. It's not worded great, but I guess that's what he is saying.
The relay only switches between the power coming through the blower motor resistors and the direct connection for high speed, so he needs to put the fan speed on HI and see if it kicks the relay on. If it does, it must be the smaller fuse for the AC, the fan switch, or the resistor pack.
