BLOWER MOTOR WORKS ON ALL SPEEDS BUT HIGH

[smoothandlow84]

Fan switch replaced, relay replaced, fan replaced...ground connections all checked and verifired. All wire checked at relay for continuity in engine compartment. I noticed that the contact for hi speed on the fan switch was charred. This charring of the contact suggested to me that a wire behind the dash to the switch may be corroded, leading to a short...and thus charring the switch contact. I ran a seperate power wire with a fused link from the blower fan to a switch that is mounted in the ash tray.


With the seperate fan switch I can at anytime have a high speed fan....either with the ac on, heater on or vent on. I no longer have the need to rely on the high speed selector of the factory switch.

It comes in handy. I can now switch the fan on HIGH without having to insert the key into the ignition and ventilate the cab.

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when the "over ride switch" is on...it illuminates. Fan now runs at full blast. Problem solved...at least for me. I didn't feel like tracing and replacing the old fan lead through and behind the dash.

 

[smoothandlow84]

Lol?
Please enlighten us @smoothandlow84 , I hope you brought enough to share with the rest of the class...

I went through the entire cicuit checklist and replaced ALL of the related parts pertaining to the ac fan and the components needed for the operation. Since the parts are cheap and readily available. ..not a big deal. The fan motor was $35...switch $15...relay $8......


As far as the new high speed switch..
$4...

new fused power lead from battery to fan to switch in ash tray....n/a....I have an ample supply of wiring and fuses in my stock to use over the years.

I was tired of tearing apart the dash and tracing wires again and again.....

 

[chengny]

I went through the entire cicuit checklist and replaced ALL of the related parts pertaining to the ac fan and the components needed for the operation. Since the parts are cheap and readily available. ..not a big deal. The fan motor was $35...switch $15...relay $8......


As far as the new high speed switch..
$4...

new fused power lead from battery to fan to switch in ash tray....n/a....I have an ample supply of wiring and fuses in my stock to use over the years.

I was tired of tearing apart the dash and tracing wires again and again.....

There was one important detail that I possibly neglected convey:

When no power is being supplied to the relay coil, the contacts default to the variable speed position. Variable voltage is then supplied to the blower windings from the resistor stack to the relay. It goes into the relay on pin 5, through the contacts, out on pin 1, and finally over to the blower on the PPL 65. So as you can see, provided the contacts are in the default (unenergized) position, the three lower speeds do not require that the relay be operational.

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It is only when high speed is desired that the relay is required to be operational. I am sure you confirmed that power was being supplied by the speed control switch to the relay coil on the ORN 52. You changed the switch and relay. But maybe I should have been more specific about the relay coil's ground leg. If the coil isn't grounded, it won't pull the relay contacts into the high speed position. And the ground connection can't be made to the blower housing because it is constructed of plastic. The relay ground wire needs to be lead right to the firewall and the schematic I provided kind of implies that it is grounded on the engine someplace:

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Anyway, I do apologize if you spent all that money, did all that testing and the coil was still non-operational. It's killing me. If possible could you please take a couple of minutes someday and confirm that there is continuity from the relay to the steel firewall on the BLK 150.

 

[Dougnsalem]

One important detail was possibly neglected:

When no power is being supplied to the relay coil, the contacts default to the variable speed position. Variable voltage is then supplied to the blower windings from the resistor stack to the relay. It goes into the relay on pin 5, through the contacts, out on pin 1, and finally over to the blower on the PPL 65. So as you can see, provided the contacts are in the default (unenergized) position, the three lower speeds do not require that the relay be operational.

You must be registered for see images attach

It is only when high speed is desired that the relay is required to be operational. I am sure you confirmed that power was being supplied by the speed control switch to the relay coil on the ORN 52. You changed the switch and relay. But maybe I should have been more specific about the relay coil's ground leg. If the coil isn't grounded, it won't pull the relay contacts into the high speed position. And the ground connection can't be made to the blower housing because it is constructed of plastic. The relay ground wire needs to be lead right to the firewall and the schematic I provided kind of implies that it is grounded on the engine someplace:

You must be registered for see images attach

Anyway, I do apologize if you spent all that money, did all that testing and the coil was still non-operational. It's killing me. If possible could you please take a couple of minutes someday and confirm that there is continuity from the relay to the steel firewall on the BLK 150.

Don't be so hard on yourself. You gave your time to help him fix it, over the internet, which isn't exactly the easiest thing to do. For free. Checking that ground is a great point, and no one(including myself) brought it up. Good thing is, when he finds the problem, everything is new and he should have no issues for a long time. Just my thoughts FWIW....

 

[echo7bravo]

chengny, are you some kind of computer? How does one retain such knowledge? AMAZING.

I do appreciate you sharing information.

It ended up being a frayed orange wire (52) right near where it connects to pin-3. Who gets the pot?

 

[Rusty Nail]

Man!

 

[smoothandlow84]

There was one important detail that I possibly neglected convey:

When no power is being supplied to the relay coil, the contacts default to the variable speed position. Variable voltage is then supplied to the blower windings from the resistor stack to the relay. It goes into the relay on pin 5, through the contacts, out on pin 1, and finally over to the blower on the PPL 65. So as you can see, provided the contacts are in the default (unenergized) position, the three lower speeds do not require that the relay be operational.

You must be registered for see images attach

It is only when high speed is desired that the relay is required to be operational. I am sure you confirmed that power was being supplied by the speed control switch to the relay coil on the ORN 52. You changed the switch and relay. But maybe I should have been more specific about the relay coil's ground leg. If the coil isn't grounded, it won't pull the relay contacts into the high speed position. And the ground connection can't be made to the blower housing because it is constructed of plastic. The relay ground wire needs to be lead right to the firewall and the schematic I provided kind of implies that it is grounded on the engine someplace:

You must be registered for see images attach

Anyway, I do apologize if you spent all that money, did all that testing and the coil was still non-operational. It's killing me. If possible could you please take a couple of minutes someday and confirm that there is continuity from the relay to the steel firewall on the BLK 150.

Yes...I made sure that thenground from the relaynand the fan are to the firewall...and confirmed that it is in fact a good ground. I am aware that thenhousing is in fact plastic, therefore not a viable ground contact. Withnall of the issues....I am still led to believe that I have a corroded wire in the dash pertaining to high speed operation.

 

[smoothandlow84]

Yes...the relay ground was to firewall and so was the blower fan. There is continuity as well.

 

[Snoots]

I went through the entire checklist that chenghy submitted...and still no high speed....none...so I went another route and obtained high speed

WTF?!

Lol?
Please enlighten us @smoothandlow84 , I hope you brought enough to share with the rest of the class...

Never mind. Okay. Thank you.

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[Rusty Nail]

lol?

 

[Snoots]

I was tired of tearing apart the dash and tracing wires again and again.....

After all that...

Well Dougnsalem, it looks like we both get to keep our money! I'm not putting the dollar I got out of my wife's purse back tho!

 

[Dougnsalem]

I was tired of tearing apart the dash and tracing wires again and again.....

After all that...

Well Dougnsalem, it looks like we both get to keep our money! I'm not putting the dollar I got out of my wife's purse back tho!

Lol. The high stakes gambling around here is pretty exciting! Shoot, you're making money without even winning....