1997 Jeep Grand Cherokee Logo
William Jackson Posted on May 07, 2012
Answered by a Fixya Expert

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Hvac motor will not stop running even with car not running

When car is off battery drains

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Adam Scott Roberts

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  • Jeep Master 1,243 Answers
  • Posted on May 08, 2012
Adam Scott Roberts
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Need to replace the blower motor control module. it apparently has shorted to ground allowing the blower motor to run all the time

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0helpful
1answer

2006 5.3L V8 Trailblazer...blower motor keeps running even when the key is off. Any thoughts?

FRONT HVAC NOT REAR, CORRECT"?
HVAC DASH? BLOWER? STUCK ON IS BAD RELAY OR
CONTROLLER TO IT. MANUAL CONTROLS OPTION1
BUT THERE IS NO POWER TO CONTROLLER KEY OFF
SO RELAY IS BAD. IT DOES HAVE B+ BATTERY FULL TIME

CHEVY TRUCK TRAILBLASZER
OPTION 2 , NOT TOLD , ALL IS DIFFERENT
BUT IT IS 2 THINGS BAD
1:BLOWER CONTROL MODULE BAD. OR
2:HVAC CONTROL MODULE BAD TELLS Above to RUN.
0helpful
1answer

2003 Honda Accord v6 AC and car alarm electrical issues, maybe connected ?

what sub model accord, v6 LX ,
manual or full climate control option??? guess full.
fuses not checked PCM scanned for DTC errors EVAC, hopeless/?
so car starts and runs sand drives ok, <<< not told that.
yes the AC brain on most modern cars is BCM brain controls
and the brain does control the AC compressor. if that is dead so be AC, THE COMPRESSOR CLUTCH, is run by PCM RELAY.
NOT TOLD OUTSIDE TEMPERATURE NOR COUNTRY../
HERE IS A LIST.
1: CHECK ALL FUSES FIRST, CAB AND ENGINE BAY ALL FUSE BOXES SKIP NONE.
2: CHECK IP CLUSTER FOR ERRORS ,ALARMS ERRORS OR LAMPS GLOWING OR IMMO LAMP SHOWS IMMO IS UNHAPPY, MODE.
3: ENGINE STARTS AND RUNS AND CAR DRIVES.?????????
4: HEAD LAMPS WORK KEY ON AND OFF. ,
5: OTHER ELECTRIC FAILURES OR JUST THE BLOWER ONLY?
6: SCAN THE pcM FOR ERRORS, AC IS CUT DEAD EVEN FOR ENGINE OVERHEATING OR OVERLOADED !!! OR IN LIMP MODE/
yah can't fix modern cars lacking a scan tool, no way./

bLOWER FACTS
PER THE SM BOOK REAL

THERE IS A BLOWER RELAY AND SOME FUSES. 12VDC SIDE.
FUSE 30 DASH
AND 21 HOOD, BOTH MUST BE GOOD. and fuse 12 V6
THE bLOWER gets GROUND FROM THIS
Audio-HVAC--Display Panel
l AND ITS BLOW POWER TRANSISTOR MODULE
SO WE KNOW THE TRANSISTOR IS off. IS CAUSE 1.
ONLY WHY REMAINS!!!!
YES THE CONTROLLER DOES NOT WANT TO RUN ANY DEAD BLOWER AND RISK ICE DAMAGE TO THE EVAP CORE.

THE Audio-HVAC Display Panel, READS MOTOR SPEED ACTUAL. speed (a kind blower tachometer wire)
IF SAY A INSECTS NEST JAMMED UP THE BLOWER FAN
THE AUDIO -HVAC, MODULE SEE THAT AND CUTS AC DEAD BY DESIGN AND HARD GOOD REASons/
the THE Audio-HVAC , has the ICE up sensor and monitors R134a
high/low switch and if wrong, tells the PCM to shut down its
Clutch solenoid to compressor ending all AC .
I am no sure what blower does.
but I can say this tell of blower works in heat mode or blower + no AC no HEAT mode. yes then the blower is not bad, nor the controller
what is wring is inputs to the controller are dead wrong
and not scanning the PCM after fuses is why you don't know.

l;earn now this works
Audio-HVAC
Display
Module
https://eautorepair.net/Marketing/Default.asp



not checking fuses first then scanning the PCm is why answers simple are not found.

like these and scads more.

Trouble Code: HVAC 12 (3.0L V6 VIN - Std)
A Problem in the Blower Motor Circuit

Trouble Code: HVAC 13 (3.0L V6 VIN - Std)
HVAC Control Unit Internal Error


Trouble Code: HVAC 14 (3.0L V6 VIN - Std)
An Open in the Evaporator Temperature Sensor Circuit (ICE Up preventions)

Trouble Code: HVAC 15 (3.0L V6 VIN - Std)
A Short in the Evaporator Temperature Sensor Circuit(ICE UP)



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0helpful
1answer

The ventilation fan for heat/ac is not working. The fuses all seem the be ok. Any thing else to look for

Did you check the proper fuses for voltage? Some fuses are hot all the time, some go hot with the key on. Even if fuses are good, if no voltage the circuit is still dead. I guess your talking about the blower motor? Can you hear it running? I don't know if you auto hvac or manual hvac? I don't know if your talking about front or rear blower motor?
Get at the blower motor, if two wire connector, that should be voltage and ground. Turn on the hvac controls, check for voltage and ground at the blower motor connector. If good voltage and ground with no blower action, suspect the blower motor.

It is possible to use jumper wires from the battery for voltage and ground to blower motor connector, just for testing to see if blower motor will run, use an inline fuse, just in case.
If you want wiring diagram, I need more info.
0helpful
1answer

Blower stays on after key is removed, now a/c works in front once I hit the highway.

Which of these systems does your vehicle have ?
HVAC Systems - Automatic
Blower Motor Control Processor
The blower motor control processor controls the speed of the blower motor by increasing or decreasing the voltage drop on the ground side of the blower motor. The HVAC control module provides a voltage signal to the blower motor control processor over the blower motor speed control circuit. As the requested blower speed increases, the HVAC control module increases the amount of time that the speed signal is modulated to ground. As the requested blower speed decreases, the HVAC control module decreases the amount of time that the signal is modulated to ground.

HVAC Systems - Manual
Air Speed - Front Control
The blower motor forces outside air into the vehicle's interior. The vehicle operator determines the blower motor's speed when the driver places the blower switch in one of 5 blower speeds. The blower motor will always operate in any switch position other than OFF, as long as the ignition switch is in the RUN position. The blower motor and mode switches are located within the HVAC control module. The blower motor OFF input is connected in series with the HVAC control module by the off blower motor control circuit.
Depending upon the selected speed, power is provided to the blower motor from either the ignition 3 voltage or battery positive voltage circuits from the fuse block. The battery positive voltage circuit only provides power when the High blower switch position is selected. Power and ground are provided to the HVAC control module by the ignition 3 voltage and the ground circuits.
Low Blower Speed
When the Low 1 blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the low blower motor control circuit. Voltage is divided between 4 series resistors, a blower relay, and the blower motor to achieve the desired blower speed. The blower motor is grounded through the ground circuit.
Medium Blower Speeds
When the Medium 1 blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the medium 1 blower motor control circuit. Voltage is divided between 3 series resistors, a blower relay, and the blower motor to achieve the desired blower speed. The blower motor is grounded through the ground circuit.
When the Medium 2 blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the medium 2 blower motor control circuit. Voltage is divided between 2 series resistors, a blower relay, and the blower motor to achieve the desired blower speed. The blower motor is grounded through the ground circuit.
When the Medium 3 blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the medium 3 blower motor control circuit. Voltage is divided between a series resistor, a blower relay, and the blower motor to achieve the desired blower speed. The blower motor is grounded through the ground circuit.
High Blower Speed
When the High blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the high blower motor control circuit. The voltage energizes the blower relay, causing the blower motor to be connected directly to the battery positive voltage circuit. The blower motor and blower motor relay are grounded through the ground circuit.

HVAC Control Module
The HVAC control module is a class 2 device that interfaces between the operator and the HVAC system to maintain air temperature and distribution settings. The battery positive voltage circuit provides power that the control module uses for keep alive memory (KAM). If the battery positive voltage circuit loses power, all HVAC DTCs and settings will be erased from KAM. The body control module (BCM), which is the vehicle mode master, provides a device on signal. The control module supports the following features:
1helpful
2answers

Hvac blower will not shut off, even when vehicle is shut off and key is out of the ignition

Hi, the likely problem is a shorted blower relay. Unfortunately, your relay is integrated into the motor/resistor assembly, so you would need to replace the whole thing to fix it. You can disable the blower high setting by pulling out the IGN3 fuse under the hood, but I'm not sure the car will run without that fuse. At least you wouldn't have to disconnect the battery to keep it from draining. Please let me know if you would like procedures to replace the blower motor assembly, and thanks for using FixYa.

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1answer

Water was leaking inside on passengers side, now

HVAC drain tube was blocked and condensation could not drain to the outside of the vehicle

as a result the water pooled inside the HVAC case leaking on the inside and killing your blower motor and probably blower motor resistor

clear the drain, replace the blower and resistor and you'll be back in business

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88 cadillac deville, ac blower fan wont shut off, even when car is turned off and key removed. I tried disconnecting the battery to reset the system but it still runs when battery reconnected. Also, car...

Ralph,
Most common cause of this is the blower fan (proper name for the fan you refer to) continuing to run is a shorted out Electronic Climate Control Module. This solid state device replaces the older style fan speed resistor block (at about 4 times the price) This unit is found on the top of the HVAC box under the hood. (HVAC means heating, ventilation and air conditioning) The HVAC box is found on the passenger side of the firewall. Look behind the A/C's accumulator. It will have an electrical wiring plug on top of it. It will be fastened to the HVAC box with a few 7mm hex head screws. Very easy to change.
FYI, do yourself a favor and replace the blower fan motor at the same time. The Electronic Climate Control Module usually fails because the motor is drawing to many amps of current. This is because it's bushings are worn out or the brushes are worn out.
This is very common on Cadillacs and Buicks.
Charlie
PS Not sure why car won't start. Either you drained the battery or blew a fuse which controls starting the engine. Need more info regarding the "no start" condition.
0helpful
1answer

Fan motor for rear hvac doesnt shut off

you have a fault somewhere my best bet is to take it in for a check up
2helpful
2answers

HVAC CLOGGED DRAIN

under the passenger side firewall at the bottom by the floor board youll see a rubber hose or nipple, shove a rod or coat hanger inside hose until you see nothing but clear water run out. you may even use the good old water hose to flush it out
good luck
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