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Blower Motor

9928 Views 22 Replies 9 Participants Last post by  rtkraken, 
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First, I want to say thanks to everyone who posts here, I have been able to find the answers to all of my questions the past 5 years without having to register or post - so thank you

The car, 2000 P-38 4.0

Now, for the problem: The air conditioning system is not working anywhere near as good as it should! I have a left hand blower motor that is not running and my wife is complaining as we live in the Mojave desert
- Pollen filters are on order - I cleaned the ones in there until they arrive - they were filthy
-Relay 7 has been replaced after looking through the relay bin at Autozone (duralast 19899 fit perfectly)
--There appears to be only minor damage to the fuse box even though the relay was burned out.
-I checked with a test light, and there is voltage to the red wire that goes into the blower motor

Is it possible that I am not getting enough amps to run the blower through the line even though the test light goes on? it was an LED test light
Is there a way to tell if the blower motor is burnt out or if it is just a bad fuse box?

Any help on narrowing down the problem and fixing this would be appreciated. My wife loves the car and I just installed headrest monitors for the kids, so I would really like to get this fixed ASAP


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D
Jos Geuze said:
If the blower is running at full speed it indicates a short to earth that bypasses the speed regulation electronics.
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the high speed relay does exactly this. it will "short" to ground the leg of the transistor that will allow full current to flow through the transistor. this gives you the highest speed.

rtkraken: the high speed relay is on the circuit board next to the two transistors.
there is a thread around here somewhere that someone posted the pn and method to replace these transistors with parts from an electronics store. a little searching should bring it up.
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ahh here it is.
viewtopic.php?f=3&t=32538&hilit=blower+motor+transistor

i had this same constant high fan setting on mine. i pulled it out and cleaned it up but to no availl. the high speed relay was working when bench tested and had good coil resistance and good contact. so I suspect the transistor(s) were just blown and allowing full current flow all the time. a replacement blower fan assembly cured my problem. and like shupack said that plastic conduit for the wiring had a few tabs broken off of it during the process. a little more time and patience and i probably could have done it but i had run out of finesse.

one item of note, don't let it go to long like this. the constant pulling of maximum amp draw through the underhood relay box will add lots of heat to this already problematic area. i am sure thats what caused my relay box #7 relay problems.
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rtkraken
FANTASTIC! :thumb: Thanks. Looks like I'll be doing the transistor replacement in a few weeks. I'll try to get a few photos and post them with the original posted procedure. Always up for a challenge if it means saving a few bucks!
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