Help! How can I get my heater fan to stop running????

[jhow66]

Clicking sound under hood is compressor clutch kicking in when you turn the fan switch on with all the levers to the left. Normal. Do you still have the anti-diesel relay as shown in the diagram? Do you have #14 brown (dotted line) line coming off fuse panel to blower switch? (as shown in diagram)

[kna4977]

Originally Posted by jhow66

Clicking sound under hood is compressor clutch kicking in when you turn the fan switch on with all the levers to the left. Normal. Do you still have the anti-diesel relay as shown in the diagram? Do you have #14 brown (dotted line) line coming off fuse panel to blower switch? (as shown in diagram)

This system never had an anti-diesel relay, but the new harness has a connection for one. I have all the wires in the right place. I have quadruple checked it.

I did make some progress. I took apart the control switch and cleaned the contacts. When it came apart, it kind of exploded on me, so I was not sure how to put the copper T-shaped piece back in (horizontal piece toward the top of the switch or toward the bottom of the switch), so I tried it both ways. With the horizontal piece toward the top, I was able to have either off or high, but the switch was very sensitive, and even the smallest amount of jarring would switch it from off to high. The other way I have low or high, but no off. Again it's sensitive that way too. I believe since I have made this progress, it would be best if I replaced the control switch. What do you think? Bad relay and control switch??

[jhow66]

Just try the switch first.

[kna4977]

Originally Posted by jhow66

Just try the switch first.

I've replaced the control switch and the relay, and still when the switch is at Hi = fan at low speed, everything else (Off, Low Med) is high fan. Any suggestions??

[kna4977]

Does anyone have a picture of the fusebox and all the wires connected to itin a truck where everything works right? If so, I would really appreciate it.

[hotrodhomi]

check the FAQ for the diagramn

[kna4977]

There's a diagram posted previously in this thread. I tried the FAQ, but didn't see the diagrams.

[hotrodhomi]

Do you have a DMM? Do you know ohms law? E=I*R

[kna4977]

Originally Posted by hotrodhomi

Do you have a DMM? Do you know ohms law? E=I*R

I don't have a DMM, but do have access to one. I'm not sure that if I had it in hand that I would know what to do although I have used one before and knew how to use it then. I should know Ohm's law, but at present my memory is failing me. Please remind me about it if possible.

[krue]

I don't remember Ohm's law, but the equation reads as
voltage=current x resistance

[67chevy2wd]

Volts = Amps x resistance
Resistance = volts / Amps
Amps = Volts / Resistance

[mrein3]

Originally Posted by kna4977

I don't have a DMM, but do have access to one.

It really is time to get a DMM out. I had to when I put my AC set-up in. Just print out the wiring diagram posted eralier and start checking voltages.

That is EXACTLY what I had to do.

[mrein3]

kna4977,
I just read your other post about the orange wire and how as soon as you hook it up you get high speed.

Now it all makes sense.

One of two things is happening.
1. Your relay is stuck in the accessory gets power position.
2. You are always supplying voltage to the signal side of the relay, which closes the contacts which powers the accessory you are trying to get lots of power to.

Since you said you already replaced the relay once, I'd look real hard at the wires coming out of the switch. In all likely hood you have #2 above happening.

If memory serves, that orange wire is a big, 12 gauge or so wire. It is meant to carry lots of current to the fan for the high-speed selection. The cigarette ligher circuit is a big beefy sucker that can carry lots of amps.

When I wired mine I made a seperate circuit off of a newer relay. My "new" circuit gets 12+ volts right off the battery and is switched on through a new relay. The "orange" wire off the battery has an in-line 20 amp fuse in it for protection. And yes I did make this new wire orange which on most GM vehicles of this vintage means "many amps worth of 12 volts in here".

Now I'm not saying you should re-wire everything. You just need to check the wires coming in and out of that switch. The best way to do that is to get the switch out of the control panel and let it dangle. Then you can select different speeds and test voltages from the back of the connector on the back of the switch. Judging from your other post I would say you are going to find 12 volts coming out of there and heading to the relay in every position of the switch that you get high speed out of.

One other possibility...
Did you wire it correctly? Is that orange wire connected directly to the purple (big wire to the fan motor) wire?

[kna4977]

If I do find 12 volts at each position, what does that mean?

Also, if the orange and purple are connected, what does that mean?

[mrein3]

Originally Posted by kna4977

If I do find 12 volts at each position, what does that mean?

Also, if the orange and purple are connected, what does that mean?

It has been a while since I did this so I spent a few minutes over lunch here studying the wiring diagram posted above.

Look at the resistor block in the diagram. 14Y should be a 14 gauge yellow wire coming from the switch. When it is switched on it should send 12 volts to the resistor block. This then should produce a voltage less than 12 volts on the 14 DBL (14 gauge dark blue wire) coming out of the resistor block.
16LBL (16 gauge light blue) coming out of the switch when it is switched on should produce a different voltage less than 12 volts on the 14 DBL wire.

14DBL out of the resistor block should switch between 3 and 6 volts or 6 and 9 volts or something like that depending on low or middle settings of your switch. I can't remember the exact numbers.

18OR out of the switch goes right to the relay so this must be the high-speed wire on the switch. It should switch the relay on putting 12 volts on 12PPL which goes to the fan. (These 12 volts come out of 12OR hooked to the CIG circuit).

The wiring harness you bought should have a 12 gauge orange wire that you hook up to "CIG" on the fuse block. This supplies the high amp supply to the relay. When you select high speed this should have 12 volts as should 12PPL.

14 BRN gets 12 volts from the fuse block to the switch.

So key switch on, fan off, 14 BRN should be 12 volts.
Key off fan on, 14 BRN should be zero.

12 OR is alwasy hot (you can use your cigarette lighter any time).

12Y, 16LBL, and 18OR behind the switch should have 12 volts with the key on and the switch in one of the positions low, medium, and high. I think it should be
18OR = high
12Y = medium
16LBL = low

Key on:
At the blower relay 18OR should be 12 volts when the fan is on high. At this time 12PPL out of the relay should have 12 volts too.
14DBL should switch between two different voltages, both below 12, when the fan is on medium or low. This same voltage should at this time be on 12PPL.

[kna4977]

Originally Posted by mrein3

It has been a while since I did this so I spent a few minutes over lunch here studying the wiring diagram posted above.

Look at the resistor block in the diagram. 14Y should be a 14 gauge yellow wire coming from the switch. When it is switched on it should send 12 volts to the resistor block. This then should produce a voltage less than 12 volts on the 14 DBL (14 gauge dark blue wire) coming out of the resistor block.
16LBL (16 gauge light blue) coming out of the switch when it is switched on should produce a different voltage less than 12 volts on the 14 DBL wire.

14DBL out of the resistor block should switch between 3 and 6 volts or 6 and 9 volts or something like that depending on low or middle settings of your switch. I can't remember the exact numbers.

18OR out of the switch goes right to the relay so this must be the high-speed wire on the switch. It should switch the relay on putting 12 volts on 12PPL which goes to the fan. (These 12 volts come out of 12OR hooked to the CIG circuit).

The wiring harness you bought should have a 12 gauge orange wire that you hook up to "CIG" on the fuse block. This supplies the high amp supply to the relay. When you select high speed this should have 12 volts as should 12PPL.

14 BRN gets 12 volts from the fuse block to the switch.

So key switch on, fan off, 14 BRN should be 12 volts.
Key off fan on, 14 BRN should be zero.

12 OR is alwasy hot (you can use your cigarette lighter any time).

12Y, 16LBL, and 18OR behind the switch should have 12 volts with the key on and the switch in one of the positions low, medium, and high. I think it should be
18OR = high
12Y = medium
16LBL = low

Key on:
At the blower relay 18OR should be 12 volts when the fan is on high. At this time 12PPL out of the relay should have 12 volts too.
14DBL should switch between two different voltages, both below 12, when the fan is on medium or low. This same voltage should at this time be on 12PPL.

Thanks for the helpful advice. I used a multimeter today to check voltage with everything wired the way it should be according to the diagram. Here are the results. Please let me know if this gives more of an indication of what is wrong, or what else I need to do to help pinpoint. Thanks

fan problem.txt


For the purposes of this illustration: b=brown, o=orange, y=yellow, lbl=light blue, dbl=dark blue, s/o=single orange, b/o=big orange double wire, p=purple






Note: With the control switch at high, the fan turns off. In all other positions, the fan blows on high regardless of off, low, or med.

[kna4977]

Okay, that didn't work so well due to formating problems. Here are the results in words. Please download the text document if this doesn't make sense. The 2 together should. I checked the control switch, resistor, and relay voltages with the ignition on then off, and the control switch moved through each position (off, low, medium and high)

Keep in mind that the fan blows on high through all control positions with the ignition turned off. When the ignition is turned on, it blows on high through all positions except when the control switch is turned to high. This is when the relay clicks and the fan cuts off.

The CONTROL SWITCH has a brown wire, an orange wire, a yellow wire and a light blue wire. With the ignition off, all wires to the control have 0v except when the control is at high fan. This is when the fan cuts off and all wires have a voltage of 11-12v. With the ignition on and the control in off position the only wire that has voltage is the brown wire. At low and medium the brown, yellow and light blue have voltage, but the orange doesn't. With the ignition on and fan switch on high all have 11-12v and fan cuts off


The RESISTOR has yellow, dark blue and light blue wires. With the control turned to off position all wires have 0v whether the ignition is on or off. With the ignition on, all wires have equal voltage (10v in low and medium, 12 v on high). With the ignition off, no wires have voltage until the control is switched to high in which they all have 12 volts.

The RELAY has a single orange wire, a double orange wire, a dark blue wire and a purple wire. With the fan on high whether the ignition is on or off all wires have 12 volts except the purple one of course. With the control at low or medium and the ignition on, all wires except the single orange wire have 10 v. With the ignition off, the double orange wire and the purple wire have 10 v and the dark blue has 0v. With the fan in off position, the double orange wire and the purple wire have 10 volts each regardless of the ignition position.

I know this is confusing. Please let me know if you have questions, and please provide me with all the help you can. This is becoming frustrating, and I know it has to be something simple.

thanks

[jhow66]

Good info. Here is the way the system works:
1--Large ORANGE wire from fuse panel goes to the relay only.
2--BROWN wire from fuse panel supplies power to fan switch.
3--With fan switch in off position there should be no power to any wire on fan switch with ignition OFF.
4--With ignition ON and fan switch OFF there should power on BROWN wire only.
5--With fan switch on HI there should be power on Orange wire from fan switch to relay-this cause the relay to close and rout power from LARGE ORANGE wire from fuse panel out thru the PURPLE wire to fan motor for high speed.
6--With fan switch in low or med.( yellow or blue wire) the power from the fan switch is routed to the resistor and back out of it on thr DARK BLUE wire to relay onto the purple wire to fan motor.
7--It is routed this way for both heat and AC ( for AC all levers are to the left so when the fan switch is moved to any speed the AC compressor clutch is engaged by a switch on back of heater box (it is closed by one on the lever cables when they are all to the left).
8--Now for the solution (I hope)--The BROWN wire from fuse panel is inserted into the wrong hole in the connector that plugs into your fan switch and has power on it with ignition switch off (this wire (BROWN) should be dead with ignition off).
9--To test, remove brown wire from fan switch-fan should not run with ignition on or off. With ignition still off check to see if you have power on the Brown wire. If you do the Brown wire is probable shorted behind your fuse panel. (fuse panel is held in place by 2 screws--easier to remove if you take the firewall connector under hood off first)
10--Also with ignition on or off there should be power on LARGE ORANGE wire on relay ONLY with fan switch OFF.
11--I will disconect my fan switch tomorrow and draw you a diagram of where each wire goes if you think this will help.
12.--disclamer-all the above info carries no warrenty.

[kna4977]

[/B]

Originally Posted by jhow66

Good info. Here is the way the system works:
1--Large ORANGE wire from fuse panel goes to the relay only. CHECK
2--BROWN wire from fuse panel supplies power to fan switch.CHECK
3--With fan switch in off position there should be no power to any wire on fan switch with ignition OFF.CHECK
4--With ignition ON and fan switch OFF there should power on BROWN wire only.CHECK
5--With fan switch on HI there should be power on Orange wire from fan switch to relay-this cause the relay to close and rout power from LARGE ORANGE wire from fuse panel out thru the PURPLE wire to fan motor for high speed. SHOULD THE IGN BE ON OR OFF? ALL WIRES HAVE 12 VOLTS HERE WHETHER THE IGN IS ON OR OFF, AND THE FAN CUTS OFF. ALL EXCEPT PURPLE WIRE ON RELAY HAVE 12 V AS WELL THEREFORE THE FAN CUTS OFF, IT JUST SHOULDN'T
6--With fan switch in low or med.( yellow or blue wire) the power from the fan switch is routed to the resistor and back out of it on thr DARK BLUE wire to relay onto the purple wire to fan motor.LOW OR MED ALL WIRES ON SWITCH HAVE 10V EXCEPT ORANGE W/IGN ON. IGN OFF NO VOLTAGE ON ANY WIRE. ALL RESISTOR WIRES HAVE 10V W/IGN ON. NO VOLTAGE WITH IT OFF. ALL ON RELAY HAVE 10V EXCEPT THE SMALL ORANGE WIRE W/IGN ON WHICH HAS 0V. THE ORANGE AND DK BLUE WIRES HAVE NO VOLTAGE W/IGN OFF THE BIG ORANGE AND PURPLE BOTH HAVE 10V THIS IS WHY THE FAN RUNS
7--It is routed this way for both heat and AC ( for AC all levers are to the left so when the fan switch is moved to any speed the AC compressor clutch is engaged by a switch on back of heater box (it is closed by one on the lever cables when they are all to the left).THIS SWITCH WORKS AS IT SHOULD
8--Now for the solution (I hope)--The BROWN wire from fuse panel is inserted into the wrong hole in the connector that plugs into your fan switch and has power on it with ignition switch off (this wire (BROWN) should be dead with ignition off).THE BROWN WIRE IS DEAD WITH THE IGN OFF, BUT THE FAN STILL RUNS. THERE IS ONLY ONE PLACE FOR IT TO GO IN THE CONNECTOR BESIDE THE ORANGE WIRE WHICH IS IN THE CENTER BESIDE THE YELLOW WIRE. THE LIGHT BLUE IS ABOVE THESE
9--To test, remove brown wire from fan switch-fan should not run with ignition on or offBUT IT DOES, THIS IS THE PROBLEM. With ignition still off check to see if you have power on the Brown wireTHERE IS NO POWER ON THE BROWN WIRE, BUT THE FAN STILL RUNS BECAUSE THE PURPLE WIRE HAS VOLTAGE. If you do the Brown wire is probable shorted behind your fuse panel. (fuse panel is held in place by 2 screws--easier to remove if you take the firewall connector under hood off first) IF YOU CAN DOWNLOAD THE TEXT DOCUMENT IT WILL PROVIDE A BETTER EXPLANATION OF THE VOLTAGES THAN THE WORDS LISTED ABOVE AND CAN HELP YOU COMPARE AND CONTRAST WITH YOUR SYSTEM. I TRIED TO POST IT DIRECTLY, BUT THE FORMATTING MESSED UP THE CHART
10--Also with ignition on or off there should be power on LARGE ORANGE wire on relay ONLY with fan switch OFF.THERE IS ALSO POWER ON THE PURPLE WIRE, THIS IS THE PROBLEM
11--I will disconect my fan switch tomorrow and draw you a diagram of where each wire goes if you think this will help.THAT WOULD BE GREAT
12.--disclamer-all the above info carries no warrenty.

[mrein3]

You need to start at the fan. The purple wire. With the ignition off, it is getting power from somewhere. You need to find that.

Follow it back. With ignition off, this should never have power.

[kna4977]

The harness I have has the wires for the anti-diesel relay. Since the system never had this relay, do I need one since the harness has a plug for it?

Also, what does this part do?

I will check on the purple wire.

[kna4977]

The anti diesel relay wiring has no power to it. I don't understand how the purple wire is getting current at the wrong time because the wire only runs from the relay to the fan unless the problem is within the relay, which is new. I switched the positions of the double orange wire and the purple wire on the relay, and now instead of high cutting it off, it puts it on low producing a voltage at the resistor of 2 volts. All the other positions produce high fan. The relay only clicks when it is placed on high. I am stumped.

[kna4977]

I know by now everyone is probably getting as tired of this thread as I am trying to get this to work, and you probably think I'm a complete idiot in the department of trying to make this work, but I need your help now more than ever to make this system work as it should.

I did some more testing, by switching the wires on the relay around. The results are as follows:

Looking at the relay, it should look like this on the bottom (please use the following as a reference):

_ is 4

_ is 1 b=blue, o=double orange, s/o=single orange, p=purple
_ is 2 _ is 3


With 4=s/o, 1=b,2=o,3=p---->with the ignition(ign) on; off and high were off and low was low, medium was high and with the switch off, nothing happened

Same as before but 2=p & 3=o--->ign on, high was medium, and all others were off. with the ign off, and control switch at high, the relay whined, all other positions nothing

With 4=s/o, 1=o, 2=p,3=b--->high was high with ign on, whine with ign off, all other positions were off

Same as before with 2=b, 3=p--->ign off, fan always on high regardless of control switch position; with the ign on, and control switch on high=fan off, all other positions resulted in the fan on high with the ign on.

With 4=s/o,1=p,2=b,3=o--->ign off, fan on high always, ign on, fan ran low with control on high and fan was high on all others and never cut off

Same as before with 2=o, 3=b--->fan ran high regardless of conditions

With 4=o, 1=b,2=s/o, 3=p--->nothing happened

Same as before with 2=p, 3=s/o--->ign off nothing; ign on, off=off, low=low, med=high and high=low (THIS IS PROBABLY AS CLOSE TO CORRECT AS I HAVE BEEN)

With 4=o,1=s/o,2=p,3=b--->ign off nothing; ign on, fan works on high when control is placed on high, all other positions result in nothing

Same as before with 2=b, 3=p--->nothing

With 4=o, 1=p,2=b,3=s/o--->clicking sound from bottom blinker in fuse box + switch off=nothing with it on, off=off, low=low, medium=medium and high=low (ALSO CLOSE TO HOW IT SHOULD BE)

Same as before with 2=s/o, 3=b--->high=high all others off with ign on; ign off, nothing

[jhow66]

'4977 I did not to get your info before dark (had company)-will get it for you tomorrow. Sorry.

[jhow66]

Here is how mine is wired: