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73-87chevytrucks.com
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Lost blower motor and no AC/ Compressor
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Topic: Lost blower motor and no AC/ Compressor (Read 3307 times)
miket007
Newbie
Posts: 21
Newbie
Lost blower motor and no AC/ Compressor
«
on:
February 24, 2018, 05:18:38 PM »
78 C10 small block with ac...working perfectly for the last 4 years....today nothing.
Fan speed switch does nothing....slide the selector lever over to def or AC...no compressor. Checked fuses inside by drivers kick...all fine. Checked for voltage at blower when it should be on...nothing. Resistor in heater core locks solid with no breaks...checked there for voltage...nothing.
Is this a blower switch or is it the switch connected to the selection lever? I pulled that piece out and apart and all looks good...nothing burned/black or broken.
What else would cause both to cease functioning?
Logged
78 C-10 Silverado Big Ten
A/C, Tilt, 350/350, posi Two-Tone
Headers, 2.5" duals with Dynomax 17749's
bd
Global Moderator
Senior Member
Posts: 6459
Re: Lost blower motor and no AC/ Compressor
«
Reply #1 on:
February 24, 2018, 06:06:20 PM »
Check for power on the brown wire that connects to the A/C selector switch.
Logged
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)
miket007
Newbie
Posts: 21
Newbie
Re: Lost blower motor and no AC/ Compressor
«
Reply #2 on:
February 25, 2018, 12:00:49 PM »
Hi BD....
Thanks.
So checking the plug that connects to the AC selector lever on the controller in the cab....with ign on "accessory"....no voltage out of any of the terminals.
I also checked the underhood relay and it seems I have power there but nothing coming out ever.
Logged
78 C-10 Silverado Big Ten
A/C, Tilt, 350/350, posi Two-Tone
Headers, 2.5" duals with Dynomax 17749's
bd
Global Moderator
Senior Member
Posts: 6459
Re: Lost blower motor and no AC/ Compressor
«
Reply #3 on:
February 25, 2018, 04:32:32 PM »
Ignore the blower relay for the time being. A/C does not power up on "accessory." Recheck for power on the brown wire that connects to the A/C selector switch with the ignition switch in the "run" position.
Logged
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)
miket007
Newbie
Posts: 21
Newbie
Re: Lost blower motor and no AC/ Compressor
«
Reply #4 on:
February 25, 2018, 06:57:39 PM »
Nothing out of that plug with the engine running.
I am not sure if it makes a difference but I have the entire HVAC controller out of the dash...the blower speed switch is disconnected when performing the above test.
Logged
78 C-10 Silverado Big Ten
A/C, Tilt, 350/350, posi Two-Tone
Headers, 2.5" duals with Dynomax 17749's
bd
Global Moderator
Senior Member
Posts: 6459
Re: Lost blower motor and no AC/ Compressor
«
Reply #5 on:
February 25, 2018, 09:52:10 PM »
With the ignition switch in the "run" position, probe both sides of the HEATER-A/C fuse using an incandescent test light (
do not
use an LED test light and
do not
use a voltmeter). Probe both end caps of the fuse and both fuse sockets (terminal clips).
Logged
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)
miket007
Newbie
Posts: 21
Newbie
Re: Lost blower motor and no AC/ Compressor
«
Reply #6 on:
February 26, 2018, 08:09:02 AM »
Thanks I will give that a shot later today
Logged
78 C-10 Silverado Big Ten
A/C, Tilt, 350/350, posi Two-Tone
Headers, 2.5" duals with Dynomax 17749's
miket007
Newbie
Posts: 21
Newbie
Re: Lost blower motor and no AC/ Compressor
«
Reply #7 on:
February 26, 2018, 09:02:21 PM »
out of all the things....it was a bad fuse. It wasn't showing blown....but it was bad.
Thanks.
Logged
78 C-10 Silverado Big Ten
A/C, Tilt, 350/350, posi Two-Tone
Headers, 2.5" duals with Dynomax 17749's
VileZambonie
Global Moderator
Senior Member
Posts: 19034
Re: Lost blower motor and no AC/ Compressor
«
Reply #8 on:
February 27, 2018, 05:36:10 AM »
A "bad fuse" is a fuse that failed to protect a circuit and allowed your truck to go up in flames. So it was a "good fuse" that did its job.
If it blows again, don't keep throwing fuses in
Logged
, ___
/ _ _ _\_
⌠ŻŻŻŻŻ' [☼===☼]
`()_);-;()_)--o--)_)
74 GMC
,
75 K5
,
84 GMC
,
85 K20
,
86 k20
,
79 K10
miket007
Newbie
Posts: 21
Newbie
Re: Lost blower motor and no AC/ Compressor
«
Reply #9 on:
February 27, 2018, 08:18:10 AM »
Yes! Wrong terminology...it didn't blow like a normal fuse does, but wouldn't pass current. Replaced it and all seems fine. I must be getting lazy in my years....I should have checked it first with a tester. It passed the visual.
Logged
78 C-10 Silverado Big Ten
A/C, Tilt, 350/350, posi Two-Tone
Headers, 2.5" duals with Dynomax 17749's
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Lost blower motor and no AC/ Compressor