High speed blower relay, (was Working on "bugs")

[mark grady]

Neely -

No, but most likely your high speed blower relay is shot, or the wire that
is the power feed to it has corrosion on the push on terminal.

The high speed blower relay kinda' looks like a horn relay. On my '77, it is
on the firewall on the passenger's side.

Mark

> -----Original Message-----
> From: owner-gmcmotorhome
> [mailtowner-gmcmotorhome]On Behalf Of Neely Butler
> Sent: Monday, December 21, 1998 4:44 PM
> To: GMC chat
> Subject: GMC: Working on "bugs"
>
>
> The heat/AC blower motor will not run on high speed, OK on lower
> speeds. Is
> their a separate fuse for high speed? If so where.
> Thanks.
> Neely B. Tenn
> '78 Eleganza
>

 

[neely butler]

Mark,
Thanks so much for your response. Will check it out ASAP. Looks like we
are in for bad weather beginning tonight.
Neely
- -----Original Message-----
From: Mark Grady
To: gmcmotorhome
Date: Monday, December 21, 1998 4:11 PM
Subject: GMC: High speed blower relay, (was Working on "bugs")

>Neely -
>
>No, but most likely your high speed blower relay is shot, or the wire that
>is the power feed to it has corrosion on the push on terminal.
>
>The high speed blower relay kinda' looks like a horn relay. On my '77, it
is
>on the firewall on the passenger's side.
>
>Mark
>
>> -----Original Message-----
>> From: owner-gmcmotorhome
>> [mailtowner-gmcmotorhome]On Behalf Of Neely Butler
>> Sent: Monday, December 21, 1998 4:44 PM
>> To: GMC chat
>> Subject: GMC: Working on "bugs"
>>
>>
>> The heat/AC blower motor will not run on high speed, OK on lower
>> speeds. Is
>> their a separate fuse for high speed? If so where.
>> Thanks.
>> Neely B. Tenn
>> '78 Eleganza
>>
>

 

[mark grady]

Neely --

Should have added this to make it more clear:

> No, but most likely your high speed blower relay is shot, or the wire that
> is the power feed to it has corrosion on the push on terminal.

With the engine off so you can hear better, turn the key on, move the top
heater / AC control lever to any setting but "max", then move the fan speed
switch up to high.

You should hear a 'clunk' as the relay energizes. That tells you how big
your problem is. If you don't hear the clunk, then the relay coil is open or
the ground to the relay is no good. You can test for voltage on the coil of
the relay with a 12 volt test light.

If you hear the clunk, it could still be the relay, but most likely it is
the voltage source to the relay. That wire (which I think is red) carries
enough current that the push on connector can go bad.

An easy check is to turn the fan on high (and it won't even be running) then
go out front and wiggle the whole plug assembly on the high speed blower
relay.

You can also check it with a 12 volt test light, the kind with an awl like
pointed end is the best way to test problems like this.

> The high speed blower relay kinda' looks like a horn relay. On my
> '77, it is
> on the firewall on the passenger's side.

This is under the little access door at the passenger's front of the coach,
not inside.

Just re-read the assumptions message and realized I could have done a better
job of explaining what I meant.

________________________________________

Note:
Eugene Fisher, I can't remember... but this is a common problem that many
first timers face...

Do you have any pictures on your web site of this relay?

Mark Grady
mgrady
N Webster, IN
'77 Kingsley

 

[ritch hwang]

In addition to checking relays, etc, re inoperative blower high speed,
here's what I have from the notes taken at a Q & A session w/Duane Simmons,
et al, at Marion:

"At the high speed setting, the blower runs direct from the alternator .
If you suddenly can't switch to high speed with the engine running while on
the road, odds are your alternator has died or you have thrown an
alternator belt." Also recommended using a 10 ga ground wire for the blower.

>>
>> The heat/AC blower motor will not run on high speed, OK on lower
>> speeds. Is
>> their a separate fuse for high speed? If so where.
>> Thanks.
>> Neely B. Tenn
>> '78 Eleganza
>>

Hope this is helpful....

As always, best regards.

~ Ritch & Betty Hwang ~ Clarkston, MI ~ mailto:rhwang
Visit our home page ~ http://www.concentric.net/~rhwang/
~ =^..^= Trinket ~ the shy Persian kitty ~
~ 76 GMC Birchaven ~ FMCA F249339 ~ RVClub 00930 ~ ICQ# 6408591~
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