Replaced blower resistor; didn't fix fan speeds
woodpecker97330
05-24-2005, 02:00 AM
The heater/ac fan in my 98 Malibu works only on high speed. I changed the blower resistor, but it still doesn’t work. The new part is ACDelco 89018413. The old part says P/N 52472768. The new part is almost an inch longer (the part that looks like a credit card) and slightly narrower. The Chevy parts guy said this new part was made by Chevy to replace the old one. The old part looks like hell: the green plastic covering on the card part is mostly broken off and the circuits look corroded.
Does this all sound right? If so, anything else I should be checking before I bite the bullet and take it to the dealer? Or should I take it to auto electric place? Any help would be appreciated!
Does this all sound right? If so, anything else I should be checking before I bite the bullet and take it to the dealer? Or should I take it to auto electric place? Any help would be appreciated!
BeatnikTermite
05-24-2005, 07:41 AM
I searched the board for ten minutes and couldn't find it...but, I remember someone else discussing this same problem.
There is also either a fuse or a relay in the enclosed relay center under the hood. This is the master control for the blower. You may want to check it out.
There is also either a fuse or a relay in the enclosed relay center under the hood. This is the master control for the blower. You may want to check it out.
woodpecker97330
05-25-2005, 08:25 PM
I searched the board for ten minutes and couldn't find it...but, I remember someone else discussing this same problem.
There is also either a fuse or a relay in the enclosed relay center under the hood. This is the master control for the blower. You may want to check it out.
BeatnikTermite:
Search on: booster resistor relay
Is that the thread you're thinking of?
There is also either a fuse or a relay in the enclosed relay center under the hood. This is the master control for the blower. You may want to check it out.
BeatnikTermite:
Search on: booster resistor relay
Is that the thread you're thinking of?
johnschmitt
05-25-2005, 10:37 PM
If I can still read a schematic...
There is a relay under the hood that by default sends whatever comes out of the blower motor resistor to the blower motor on settings 1-4. When you turn the control to position 5 it trips the relay and sends the full 12 volts to the motor completely bypassing the resistor. I'd check that guy. If the circut between the dark blue and purple wires is open the resistor can't send current to the motor. If that isn't it, check the dark blue and purple wires. I don't think it's a fuse because the way it's set up both fuses concerning this have to be good for the high setting to work.
hope you find the problem!
There is a relay under the hood that by default sends whatever comes out of the blower motor resistor to the blower motor on settings 1-4. When you turn the control to position 5 it trips the relay and sends the full 12 volts to the motor completely bypassing the resistor. I'd check that guy. If the circut between the dark blue and purple wires is open the resistor can't send current to the motor. If that isn't it, check the dark blue and purple wires. I don't think it's a fuse because the way it's set up both fuses concerning this have to be good for the high setting to work.
hope you find the problem!
woodpecker97330
06-01-2005, 07:42 PM
If I can still read a schematic...
There is a relay under the hood that by default sends whatever comes out of the blower motor resistor to the blower motor on settings 1-4. When you turn the control to position 5 it trips the relay and sends the full 12 volts to the motor completely bypassing the resistor. I'd check that guy. If the circut between the dark blue and purple wires is open the resistor can't send current to the motor. If that isn't it, check the dark blue and purple wires. I don't think it's a fuse because the way it's set up both fuses concerning this have to be good for the high setting to work.
hope you find the problem!
Thanks for the ideas! I've done the following:
-I checked the relays under the hood by switching the 2 that are alike (one is HVAC, the other might be related) and the blower still only worked on high (5) position.
-I checked all fuses that looked like they could be related; all are OK.
-I looked closely at the old blower resistor and the harness it plugs into. There are 5 contact points; they all have some green-blue corrosion on them, especially the one on the end that seems slightly separated from the other 4 in the harness. I'm thinking maybe the wiring into the harness is bad, something to have checked.
-I made a tentative appointment with an auto electric place to take it in Friday a.m. Anything else I should tell or ask them or try myself before then? I'll take what you wrote, johnschmitt, since it is beyond the realm of my abilities and tools; thanks!!.
There is a relay under the hood that by default sends whatever comes out of the blower motor resistor to the blower motor on settings 1-4. When you turn the control to position 5 it trips the relay and sends the full 12 volts to the motor completely bypassing the resistor. I'd check that guy. If the circut between the dark blue and purple wires is open the resistor can't send current to the motor. If that isn't it, check the dark blue and purple wires. I don't think it's a fuse because the way it's set up both fuses concerning this have to be good for the high setting to work.
hope you find the problem!
Thanks for the ideas! I've done the following:
-I checked the relays under the hood by switching the 2 that are alike (one is HVAC, the other might be related) and the blower still only worked on high (5) position.
-I checked all fuses that looked like they could be related; all are OK.
-I looked closely at the old blower resistor and the harness it plugs into. There are 5 contact points; they all have some green-blue corrosion on them, especially the one on the end that seems slightly separated from the other 4 in the harness. I'm thinking maybe the wiring into the harness is bad, something to have checked.
-I made a tentative appointment with an auto electric place to take it in Friday a.m. Anything else I should tell or ask them or try myself before then? I'll take what you wrote, johnschmitt, since it is beyond the realm of my abilities and tools; thanks!!.
johnschmitt
06-02-2005, 02:56 AM
Just a quick edit of my above post...
The dark blue wire I mentioned is the wire coming OUT of the resistor going TO the relay under the hood for speeds 1-4. The purple wire comes OUT of the relay and is the lead that feeds the blower motor no matter what speed it's set on. If something gets in the way of the dark blue wire in particular, speeds 1-4 won't work.
Diagnostics:
You basically test a spot on the hot wire in the circut. If it's cold you probe farther back until it's hot. If it's hot you probe forward until it goes cold. Your problem must be somewhere between the two adjacent spots that were different.
I would start by backprobing the dark blue wire on the resistor with the fan on various settings between 1 and 4. To backprobe a connection you stick a needle in the back end of the connector where the wire comes out and connect a voltmeter between the needle and a ground from somewhere. You should get various readings less than 12 volts. If nothing, see if you get 12 volts from any of the other 4 wires. If not, the switch on the dash is probably dirty.
If all that comes out ok, see if you have current at the appropriate terminal on the relay then at the purple wire on the blower motor.
That's the whole circut for 1-4 with the exception of things it has in common with the circut for number 5.
P.S. the Haynes manual for the malibu seems to have fairly accurate wiring diagrams in it should you need them.
The dark blue wire I mentioned is the wire coming OUT of the resistor going TO the relay under the hood for speeds 1-4. The purple wire comes OUT of the relay and is the lead that feeds the blower motor no matter what speed it's set on. If something gets in the way of the dark blue wire in particular, speeds 1-4 won't work.
Diagnostics:
You basically test a spot on the hot wire in the circut. If it's cold you probe farther back until it's hot. If it's hot you probe forward until it goes cold. Your problem must be somewhere between the two adjacent spots that were different.
I would start by backprobing the dark blue wire on the resistor with the fan on various settings between 1 and 4. To backprobe a connection you stick a needle in the back end of the connector where the wire comes out and connect a voltmeter between the needle and a ground from somewhere. You should get various readings less than 12 volts. If nothing, see if you get 12 volts from any of the other 4 wires. If not, the switch on the dash is probably dirty.
If all that comes out ok, see if you have current at the appropriate terminal on the relay then at the purple wire on the blower motor.
That's the whole circut for 1-4 with the exception of things it has in common with the circut for number 5.
P.S. the Haynes manual for the malibu seems to have fairly accurate wiring diagrams in it should you need them.
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