2000 Alero HVAC & Fuel Electrical ?'s

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Dave - 22 Jan 2006 18:28 GMT

I, unfortunately have two problems I am hoping someone can help me with.

First, I am having some difficulties fixing a problem I have with my
HVAC system on my alero. The problem is that the blower will only
operate on the high speed setting (the other 4 setpoints on the knob do
not cause the motor to do anything).

The first time this happened was nearly 18 months ago, at which time I
replaced the resistor pack which fixed the problem. Around 4 months ago
the same thing happened. I put another resistor pack in and this time
it didnt fix it. At which point I removed the replacement pack and put
the old one back in (I didnt smell any burnt or shortcircuit type smell
when I put the new one in). After that I found that the wiring harness
for the blower motor fit very loosely so I replaced it. Since I
installed and then removed, because it didnt fix the problem, a new HVAC
controller (the part the sits behind the mid dash board that the knobs
interact with).

I don't know what to try next, the fact that at one point a new resistor
pack fixed things only confuses me more. I'm not even sure what other
points I might mess around with a voltmeter on.

The second problem started 2 weeks ago and involves the fuel gauge in
the driver instrument cluster. Two weeks ago on a couple hundred mile
trip I filled the car up and upon leaving the gas station the fuel
needle dropped to empty and then a few minutes later back up to full.
Since then this has not occurred. Instead my indicated fuel is way off
(essentially I am using up about a half tank before it even indicates
on quarter used and I might have 1.5 to 2 gallons left when it indicates
3/4 empty). It isn't a significant problem because I always rely on the
trip odometer but I would like to fix it.

The only other information is that about 3 months ago I had to replace
the gas cap because the seal had broken down to the point where I got a
check engine light.

Any ideas?

I appreaciate any help.

Dave
djmartin555@hotmail.com

2000 olds alero
1998 pontaic grand prix gt
2005 honda interceptor

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Silver Surfer - 23 Jan 2006 17:57 GMT

Some possibilities;

20-amp HVAC BLOWER fuse in the right hand instrument panel junction block

Failed normally closed contact in the blower motor relay (located in the
underhood junction block)

Burned or corroded terminal in one of the relevant connectors

Double check the resistor pack with an ohmmeter; terminal E is the output
and should have a different low resistance to terminals A, B, C, and D.

Use your voltmeter to check that voltage is arriving at a different terminal
(B, C, A, D is the sequence from low, M1, M2, and M3 speeds) on the resistor
pack as the speed switch is placed in each position.

> I, unfortunately have two problems I am hoping someone can help me with.
>
[quoted text clipped - 42 lines]
> 1998 pontaic grand prix gt
> 2005 honda interceptor

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Brian - 24 Jan 2006 00:33 GMT

I agree with the relay problem...had a similar issue with my 79 delta,
resistor pack fixed it for a while but replacing the blower relay at the
same time did the trick

Your gas gauge may be the sending unit on the pump failing. Not sure how to
check that but replacing it means dropping the tank

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Dave - 27 Jan 2006 02:41 GMT

Thanks for the help, I'll try those this weekend. Previously I had checked
the 20-amp fuse and it was fine. I looked at the blower motor relay but
didnt know what i was looking for.

How can I tell if the contact in the blower motor relay has failed?

Dave

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Silver Surfer - 27 Jan 2006 15:27 GMT

A good way to test the contact is to pull the relay from its socket and
measure resistance across the normally closed contact's terminals with a
volt-ohmmeter. Should be essentially zero ohms.

Barring that you can turn everything on and check for voltage with a test
light before and after the relay contact while it is plugged in. If the
control is not on high speed the test light should light up if the contact
is good.

> Thanks for the help, I'll try those this weekend. Previously I had
> checked
[quoted text clipped - 4 lines]
>
> Dave

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