Author Topic: Heat/AC Blower Motor Issue  (Read 178 times)

Offline RedJeepster1

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Heat/AC Blower Motor Issue
« on: January 10, 2018, 06:26:01 PM »
Hey guys,

So this past weekend I replaced the heater core in Emily's Jeep. It is a 2000 XJ. Job went mostly fine, until we got everything back together and the fan heater fan won't spin.

Initial symptoms are that the switch appears to work, as changing the position causes the lights to dim showing there's a load. The fan does not spin in any position. I left the switch on for about 30 seconds and I started to smell burning rubber so I promptly turned it off before hopefully any real damage was done.

Monday I changed out the resistor thinking that maybe that was the issue since I don't know much about how these work, that made no noticeable difference. in the symptoms.

Today I pulled the fan out of the box through the firewall. I ohm tested the fan and it shows 0.7 ohm's of resistance, same as the new fan I purchased. Since it ohm tested the same, I don't think it's a fan issue. At the plug going into the heater, I get basically 0 volts when the heater is off, and when the heater is on I get 12 volts. Worth noting that I get 12 volts regardless of the fan speed switch's position (does this mean the fan just gets more amps on a higher setting and the same voltage). I also tried plugging the new fan in and I get the same results as the old fan.

Looking around in the heater core box, I don't see any obstructions that would prevent the fan from spinning.

What am I missing? Where else should I be looking? Thanks in advance.
88 YJ, D30, D35, 4.10's, 4.6L Stroker, MPFI, Skyjacker 2.5" Lift, 33's
00 XJ, HP30, Front Truss, WJ Knuckles, High Steer, 3 link, Locked C8.25 w/ Chromo's, IRO Leafs, 4.56's, Rebuilt 4.0, JK Rubi Wheels, 35's

Offline JeepinMaxx

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Re: Heat/AC Blower Motor Issue
« Reply #1 on: January 10, 2018, 07:00:58 PM »
On my 99 TJ replaced the motor and resistor - still nothing.  Ended up switching out the switch cluster in the dash...
99TJ Tummy Tuck and SYE, Front D30 with alloy shafts, Detroit locker 4.56, Rear D44, ARB locker 4.56.  Detoursusa.com Rear bumper, Superwinch EP9000 Front Cage



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Online MassJK

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Re: Heat/AC Blower Motor Issue
« Reply #2 on: January 10, 2018, 07:19:28 PM »
Double check the grounds.

and try applying 12 directly from a battery to the fan.

.7 ohms  to me is a short .  near 20 amps @12 volts.

the speed switch is just a resistor, limits current to slow fan.  you may not see that without the fan in the circuit depending on your meter
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Online A new level

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Re: Heat/AC Blower Motor Issue
« Reply #3 on: January 10, 2018, 07:54:46 PM »
If you like you can barrow my power probe it makes chasing down electrical problems a lot easier.
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Online MassJK

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Re: Heat/AC Blower Motor Issue
« Reply #4 on: January 10, 2018, 08:07:21 PM »
If you like you can barrow my power probe it makes blowing up electrical things a lot easier.
FIFY
Quote from: Mrs. Whoopie Pies
Then we have those guys that feel like constant cornmeal in ones pants . Alan for example.

Online A new level

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Re: Heat/AC Blower Motor Issue
« Reply #5 on: January 10, 2018, 08:09:39 PM »
If you like you can barrow my power probe it makes blowing up electrical things a lot easier.
FIFY

Hahaha
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 Build thread http://forum.northeastjeep.org/index.php?topic=38405.new#new

Offline RedJeepster1

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Re: Heat/AC Blower Motor Issue
« Reply #6 on: January 10, 2018, 08:59:31 PM »
So it turned out to be a clearance issue. For some reason the fan was hitting the back of the housing. Even with the fan seated all the way , it was still hitting. So like any good XJ owner I broke out the cutoff wheel o I could avoid the problem rather then fix the issue. It seems to be working great now. Currently in a test drive seeing if the heater core is actually better. So far so good.


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88 YJ, D30, D35, 4.10's, 4.6L Stroker, MPFI, Skyjacker 2.5" Lift, 33's
00 XJ, HP30, Front Truss, WJ Knuckles, High Steer, 3 link, Locked C8.25 w/ Chromo's, IRO Leafs, 4.56's, Rebuilt 4.0, JK Rubi Wheels, 35's

Online MassJK

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Re: Heat/AC Blower Motor Issue
« Reply #7 on: January 10, 2018, 09:02:55 PM »
at locked rotor it didn't blow a fuse?
Quote from: Mrs. Whoopie Pies
Then we have those guys that feel like constant cornmeal in ones pants . Alan for example.

Offline RedJeepster1

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Re: Heat/AC Blower Motor Issue
« Reply #8 on: January 10, 2018, 09:12:39 PM »
Nope, it did not. But I mostly was testing it on the lowest fan setting.


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88 YJ, D30, D35, 4.10's, 4.6L Stroker, MPFI, Skyjacker 2.5" Lift, 33's
00 XJ, HP30, Front Truss, WJ Knuckles, High Steer, 3 link, Locked C8.25 w/ Chromo's, IRO Leafs, 4.56's, Rebuilt 4.0, JK Rubi Wheels, 35's

Online MassJK

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Re: Heat/AC Blower Motor Issue
« Reply #9 on: January 10, 2018, 09:15:17 PM »
interesting.    blower fuse is 10A   right?
Quote from: Mrs. Whoopie Pies
Then we have those guys that feel like constant cornmeal in ones pants . Alan for example.

Offline RedJeepster1

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Re: Heat/AC Blower Motor Issue
« Reply #10 on: January 10, 2018, 09:16:43 PM »
Pretty sure this one has a 30 which seemed too big. Probably why it didn’t blow. I’ll have to check my silver or red Jeep and see what size those have for the blower motor.


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88 YJ, D30, D35, 4.10's, 4.6L Stroker, MPFI, Skyjacker 2.5" Lift, 33's
00 XJ, HP30, Front Truss, WJ Knuckles, High Steer, 3 link, Locked C8.25 w/ Chromo's, IRO Leafs, 4.56's, Rebuilt 4.0, JK Rubi Wheels, 35's

Online MassJK

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Re: Heat/AC Blower Motor Issue
« Reply #11 on: January 10, 2018, 09:29:57 PM »
ten seems low but I dont think it should be 30
Quote from: Mrs. Whoopie Pies
Then we have those guys that feel like constant cornmeal in ones pants . Alan for example.

Offline JeepinMaxx

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Re: Heat/AC Blower Motor Issue
« Reply #12 on: January 10, 2018, 10:06:15 PM »
Good catch!  30A fuse will burn down connections if there's a problem.  I thought my fan blower was a 20A - but maybe XJ's had higher gauge connections than TJ's...  (BTW MassXJ - I caught your locked rotor motor amperage reference  :wink: )
99TJ Tummy Tuck and SYE, Front D30 with alloy shafts, Detroit locker 4.56, Rear D44, ARB locker 4.56.  Detoursusa.com Rear bumper, Superwinch EP9000 Front Cage



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Online MassJK

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Re: Heat/AC Blower Motor Issue
« Reply #13 on: January 10, 2018, 10:12:46 PM »
I try to keep it dumb. 
Quote from: Mrs. Whoopie Pies
Then we have those guys that feel like constant cornmeal in ones pants . Alan for example.

Offline JeepinMaxx

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Re: Heat/AC Blower Motor Issue
« Reply #14 on: January 10, 2018, 11:35:35 PM »
I try to keep it dumb. 

 :wink: As a Baldor motor supplier I love when folks toss tech references

99TJ Tummy Tuck and SYE, Front D30 with alloy shafts, Detroit locker 4.56, Rear D44, ARB locker 4.56.  Detoursusa.com Rear bumper, Superwinch EP9000 Front Cage



"We don't need more gun control - we need ASSHOLE CONTROL"