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bcobe
New User
Jun 5, 2008, 12:11 PM
Post #1 of 8
(1470 views)
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I have a'98 Pontiac Grand Am and a year ago one speed of the heater blower(fan) started acting up. It would cut out when I stepped on the gas then start again when I get up to speed. Eventually it quit working while the other speeds were ok. So I started using the next speed up and now it is doing the same thing on the new speed, while the other two speeds that are left are ok. Is this the fan motor or a voltage regulator? what's the fix?
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DanD
Veteran
/ Moderator
Jun 5, 2008, 2:41 PM
Post #2 of 8
(1464 views)
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90% of the time when we hear this kind of problem with GM heater blower motor, it turns out to be the blower motor resistor assembly.
You’ll find this assembly close to the blower motor housing under the hood. If you’re not sure what or where the motor is; turn the ignition switch to the run position and then the heater fan; follow the noise.
The wires that plug into the blower motor go to the resistor assembly. Usually only about a 10 or 15 minute job to replace.
Dan.
Canadian "EH"
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bcobe
New User
Jun 7, 2008, 6:01 AM
Post #3 of 8
(1454 views)
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That's great to hear. I looked under the hood and found the resistor assembly. I ordered one and will put it in Monday morning. Thanks!!!!
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bcobe
New User
Jun 12, 2008, 9:44 AM
Post #4 of 8
(1443 views)
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Got the resistor replaced and there is no change in blower speed. Still cuts out when I step on the gas untill I get up to speed. Two other speeds work fine. Any other ideas?
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DanD
Veteran
/ Moderator
Jun 12, 2008, 2:00 PM
Post #5 of 8
(1440 views)
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Sorry; like I said most times the resistor is the issue and I guess I should have paid more attention to your post about it shutting off while accelerating; which doesn’t make much sense at all.
The only thing I can think of right off hand is that possibly, the torque on the engine during acceleration, is pulling on a wiring harness, causing either a power feed or the ground for the blower motor to disconnect?
Maybe try turning on the blower motor (engine off) and start pulling and wigging any wiring harness that you can get your hands on?
Dan.
Canadian "EH"
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bcobe
New User
Jun 13, 2008, 4:20 AM
Post #6 of 8
(1432 views)
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I will try that, but want to add that when I run the blower and rev up the engine in park, it doesn't do it. Can it be that the blower motor windings are getting weak for those speeds?
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jun 13, 2008, 5:31 AM
Post #7 of 8
(1430 views)
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As Dan said, when speeds requested change the problem or especially when HIGH fan only works the resistor is the likely problem.
Same behavior with a new one rules that out. This pic shows the engine side with two wires going to the motor - this shows PS pump already moved but you get the idea. Those two wires must have good contact. One grounds the flare of the housing to body ground which could be intermittent. You could just use a jumper wire and add a temp ground to any good contact on the bolts of the flared part to engine ground while key on, engine off but when blower would and should be running and if added ground kicks it to check integrity of the regular one.
Makes sure those wiring connections are good - sometimes just removing and replacing gets a better contact.
Still nothing? Try tapping on the body of the motor with a light tap with hammer and an extention bar if needed - if that makes it behave for the while I'll blame the motor as tight at its bearings or moderate contact with it's brushes inside - not serviceable.
This problem is a little different so I'm trying to focus on what might snap it to with the engine off but key on "run" for the testing to rule out engine vibrations and alternator outputs as a cause.
Hit or miss with this and what works of any of those tries targets the problem a bit better. If a spade connector seems like the problem, try slightly distorting the spade with needled nose plier a tad to get a better connection, clean contact and I like a drop of WD40 or something on them to protect against corrosion.
Note: Depending on engine - either alt or PS pump is in the way of that motor to remove it,
T
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DanD
Veteran
/ Moderator
Jun 13, 2008, 6:21 AM
Post #8 of 8
(1426 views)
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Follow Tom’s advice and let us know what you find.
What I meant by engine torque is when you’re pulling away from a stop and accelerating, the engine will actually try and twist on its mounts. It’s not unusual to have an engine move an inch or two on hard acceleration and a lot more then that if you have a weak or broken mount.
You could try applying some torque to the engine by putting it in drive and or reverse; with one foot on the brake and then giving some throttle with the other.
Don’t hold the throttle on to long because while doing this the transmission temperature will go up by quite a lot and you don’t want to overheat it.
Dan.
Canadian "EH"
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