Blower Speed for New Build


 
M

MLewisClark

New member
I've finished my heater meter, and it booted up first try! After a bit of tinkering I think I've got everything working except the blower doesn't change speeds. When the heatermeter says 100%, the blower speed is the same as 10%, or even 0%. Any ideas what may be happening? I've attached some photos below. Thanks for you help!

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Until your target temp is reached, the fan will stay on 100%, try lowering the target to what the probe says at room temp.
 
Thank you Ralph Trimple. Below are a couple photos of the part I believe you are talking about. Is this the MOSFET that drives the blower? If so I don't believe I have a solder bridge.

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After re-reading Ralph's reply, I now think the part you are speaking of is part # "Q3". If so, could the issue be that I did solder the tab to the PCB? The instructions say it's "not required" to solder the tab to the PCB with the standard blower - but I read that as it's not required, but wouldn't hurt. So I went ahead and soldered the tab in case I got a different blower in the future. I'm at work now and can't try un-soldering the tab - does that sound like the issue to you heatermeter/electronics wizards?
 
There is only one transistor that is larger than the rest, I thought that would give you the clue you need. It's not the tab that I am talking about, its the three legs on the transistor. See the photo below, from what I can see with the low detail in the picture it appears there is a solder bridge between the two legs where the arrow is pointing...


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Thank you Ralph. I apologize for having to deal with my ignorance - I'm still learning resistor/transistor/mosfet/capacitor/diode/etc. I have zero knowledge as to the difference between them, and what their functions are. I'm at work now, but will check when I get home. I'll upload better photos if necessary and will report back either way. Again - thank you.
 
I cleaned between the connections and added a bit more solder and the blower still only has 1 speed. Attached are higher res photos. Any other suggestions? How would one go about testing the Q3 component to make sure it's good?

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OK, solder looks better. I notice the transistor looks like it got pretty hot when you were soldering the tab, not sure if that is just flux or if the transistor kinda melted a bit? (prob just flux) Not impossible that you over heated the MOSFET during soldering, but not the most likely scenario either....

Speaking of most likely scenarios... Are you sure you are using the proper wires from the CAT5 cable? There is +5V in the CAT5 jack to power the servo right next to the BLOW pin, if you were to connected the +5v wire to the blower by mistake it might spin at a slow speed.... Verify by continuity you are using the right wires...

If you have verified you are using the right wires, then next I would go in the HM Config and change the blower from VOLTAGE mode to PULSE mode. In Pulse mode it doesn't use the feedback circuit, so if it works in Pulse mode check what's going on with the feedback circuit.
 
Ralph - Your help has been most appreciated. I assumed that I had grabbed a standard CAT 5 patch cable (I didn't even look at the terminations, I just cut an end off and went to work. Turns out I grabbed a CAT 5 cable terminated as follows (white orange/orange; white blue/blue; white green/green; white brown/brown). Therefore the middle two wires were blue/white green and not blue/white blue. Once I wired it properly it worked great! Thanks so much! Now I just need to get this sucker connected to my WSM. Glad my only issue was so easily fixed.
 
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