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Dash fan has only hi speed

K
kcloutier@nyc.rr.com
Tue, Jun 15, 2021 11:12 PM

Hello - my coach has only hi speed on the heater/ac blower. It has a new fan motor and relay.  Nothing happens on lo and medium.
Any guidance will be greatly appreciated

Kevin Cloutier -'77 Eleganza II-455, 6 disk brakes, Edelbrock carb, headers, , resident of NYC and Dingmans Ferry, Pa.
'72 MGB-GT & '73 MGB convertible
Member GMCMI since 8/20

Hello - my coach has only hi speed on the heater/ac blower. It has a new fan motor and relay. Nothing happens on lo and medium. Any guidance will be greatly appreciated -- Kevin Cloutier -'77 Eleganza II-455, 6 disk brakes, Edelbrock carb, headers, , resident of NYC and Dingmans Ferry, Pa. '72 MGB-GT & '73 MGB convertible Member GMCMI since 8/20
MC
Matt Colie
Tue, Jun 15, 2021 11:58 PM

Kevin,

That means that either the switch or the resistor is bad (maybe both).  But the resistor is easier to get to.  It is in the left side of the HVAC case
and has a multi-wire plug on it.  If pulling and pushing that that plug doesn't get it, try measuring resistance between all the terminals and most
likely one is open.  Those resistors are cheap and real available.

Hope it is not the switch.

Matt

Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit

Kevin, That means that either the switch or the resistor is bad (maybe both). But the resistor is easier to get to. It is in the left side of the HVAC case and has a multi-wire plug on it. If pulling and pushing that that plug doesn't get it, try measuring resistance between all the terminals and most likely one is open. Those resistors are cheap and real available. Hope it is not the switch. Matt -- Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms SE Michigan - Near DTW - Twixt A2 and Detroit
KH
Ken Henderson
Wed, Jun 16, 2021 12:00 AM

Kevin,

The HVAC blower runs, in the lower switch positions, through the resistor
pack mounted in the left side of the HVAC box, beneath the driver-side
hood.  In HI, it bypasses that resistor and runs directly on alternator
output voltage.  You can see all this clearly on the coach wiring diagram
in the back of the maintenance manual.

Check that resistor pack -- do sometimes fail, though rarely..

Ken H.

On Tue, Jun 15, 2021 at 7:13 PM kcloutier@nyc.rr.com wrote:

Hello - my coach has only hi speed on the heater/ac blower. It has a new
fan motor and relay.  Nothing happens on lo and medium.
Any guidance will be greatly appreciated

Kevin Cloutier -'77 Eleganza II-455, 6 disk brakes, Edelbrock carb,
headers, , resident of NYC and Dingmans Ferry, Pa.
'72 MGB-GT & '73 MGB convertible
Member GMCMI since 8/20


GMCnet mailing list
Unsubscribe or Change List Options:

Kevin, The HVAC blower runs, in the lower switch positions, through the resistor pack mounted in the left side of the HVAC box, beneath the driver-side hood. In HI, it bypasses that resistor and runs directly on alternator output voltage. You can see all this clearly on the coach wiring diagram in the back of the maintenance manual. Check that resistor pack -- do sometimes fail, though rarely.. Ken H. On Tue, Jun 15, 2021 at 7:13 PM <kcloutier@nyc.rr.com> wrote: > Hello - my coach has only hi speed on the heater/ac blower. It has a new > fan motor and relay. Nothing happens on lo and medium. > Any guidance will be greatly appreciated > -- > Kevin Cloutier -'77 Eleganza II-455, 6 disk brakes, Edelbrock carb, > headers, , resident of NYC and Dingmans Ferry, Pa. > '72 MGB-GT & '73 MGB convertible > Member GMCMI since 8/20 > _______________________________________________ > GMCnet mailing list > Unsubscribe or Change List Options: >
KB
Ken Burton
Wed, Jun 16, 2021 12:43 AM

Another thing to check is the connections at the relay.  They sometimes burn open.  Look closely at the relay connections / terminals and also the
resistor terminals for signs of burning.

Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

Another thing to check is the connections at the relay. They sometimes burn open. Look closely at the relay connections / terminals and also the resistor terminals for signs of burning. -- Ken Burton - N9KB 76 Palm Beach Hebron, Indiana
K
kcloutier@nyc.rr.com
Wed, Jul 21, 2021 6:59 PM

Hi Folks- Following up on my dash fan - I have a new fan motor, new relay and I just installed a new switch. I pulled the peculiar flash gordon
resister gizmo out  and cleaned the plug and connection -Still doesn't work. Is there an update on that gizmo and do you know where I would get a new
resister pack?

Many Thanks, Kevin

Kevin Cloutier -'77 Eleganza II-455, 6 disk brakes, Edelbrock carb, headers, , resident of NYC and Dingmans Ferry, Pa.
'72 MGB-GT & '73 MGB convertible
Member GMCMI since 8/20

Hi Folks- Following up on my dash fan - I have a new fan motor, new relay and I just installed a new switch. I pulled the peculiar flash gordon resister gizmo out and cleaned the plug and connection -Still doesn't work. Is there an update on that gizmo and do you know where I would get a new resister pack? Many Thanks, Kevin -- Kevin Cloutier -'77 Eleganza II-455, 6 disk brakes, Edelbrock carb, headers, , resident of NYC and Dingmans Ferry, Pa. '72 MGB-GT & '73 MGB convertible Member GMCMI since 8/20
KH
Ken Henderson
Wed, Jul 21, 2021 10:32 PM

Kevin,

You probably took care of this, but just in case:  The fan motor gets its
ground via a jumper wire from its case to the body ground, bypassing its
rubber isolation mounts.  Those tend to loosen and lose contact.  Try using
another jumper wire from bare metal on the motor housing to a known good
ground.

Failing that, it's time to get a test light or multimeter out and start
following the voltage from the fuse, through the switch, etc., etc.

Ken H.

On Wed, Jul 21, 2021 at 2:59 PM kcloutier@nyc.rr.com wrote:

Hi Folks- Following up on my dash fan - I have a new fan motor, new relay
and I just installed a new switch. I pulled the peculiar flash gordon
resister gizmo out  and cleaned the plug and connection -Still doesn't
work. Is there an update on that gizmo and do you know where I would get a
new
resister pack?

Many Thanks, Kevin

Kevin Cloutier -'77 Eleganza II-455, 6 disk brakes, Edelbrock carb,
headers, , resident of NYC and Dingmans Ferry, Pa.
'72 MGB-GT & '73 MGB convertible
Member GMCMI since 8/20


GMCnet mailing list
Unsubscribe or Change List Options:

Kevin, You probably took care of this, but just in case: The fan motor gets its ground via a jumper wire from its case to the body ground, bypassing its rubber isolation mounts. Those tend to loosen and lose contact. Try using another jumper wire from bare metal on the motor housing to a known good ground. Failing that, it's time to get a test light or multimeter out and start following the voltage from the fuse, through the switch, etc., etc. Ken H. On Wed, Jul 21, 2021 at 2:59 PM <kcloutier@nyc.rr.com> wrote: > Hi Folks- Following up on my dash fan - I have a new fan motor, new relay > and I just installed a new switch. I pulled the peculiar flash gordon > resister gizmo out and cleaned the plug and connection -Still doesn't > work. Is there an update on that gizmo and do you know where I would get a > new > resister pack? > > Many Thanks, Kevin > -- > Kevin Cloutier -'77 Eleganza II-455, 6 disk brakes, Edelbrock carb, > headers, , resident of NYC and Dingmans Ferry, Pa. > '72 MGB-GT & '73 MGB convertible > Member GMCMI since 8/20 > _______________________________________________ > GMCnet mailing list > Unsubscribe or Change List Options: >
JR
John R. Lebetski
Thu, Jul 22, 2021 12:49 AM

Without a meter, this is getting to be like Facebook advice—- guessing.
All speeds go through the relay. Deenergized it passes the 1, 2, 3, voltage to the motor on the normally closed contacts.  Energized (hi and engine
running) the relay contacts flip to the normally open contacts and pass alternator voltage to motor.  You did not replace the resistor pack. You could
inspect and meter each wire coil to pins to confirm some Ohm reading not open. Also the new relay or old resistor may still not be making contact at
the old oxidized connectors.  I spray all that with Caig D5 before plugging in and sometime you STILL have to wiggle them to get them to work.
That’s why GM went to Weatherpak connectors in the years after our coaches. Try the meter tests and the wiggle method.  If that fails you need to
meter voltage per schematic source to motor.

John Lebetski
Woodstock, IL
77 Eleganza II

Without a meter, this is getting to be like Facebook advice—- guessing. All speeds go through the relay. Deenergized it passes the 1, 2, 3, voltage to the motor on the normally closed contacts. Energized (hi and engine running) the relay contacts flip to the normally open contacts and pass alternator voltage to motor. You did not replace the resistor pack. You could inspect and meter each wire coil to pins to confirm some Ohm reading not open. Also the new relay or old resistor may still not be making contact at the old oxidized connectors. I spray all that with Caig D5 before plugging in and sometime you STILL have to wiggle them to get them to work. That’s why GM went to Weatherpak connectors in the years after our coaches. Try the meter tests and the wiggle method. If that fails you need to meter voltage per schematic source to motor. -- John Lebetski Woodstock, IL 77 Eleganza II