8.9K subscribers Subscribe 1.6K views 2 years ago how to diagnose fan motor from wiring diagram with blower resistor Network this explains all of the speeds of the fan motor and how the...Dec 9, 2020 · Buy Now!New Blower Motor Resistor from 1AAuto.com http://1aau.to/ib/1AHBR00086The heat and air condition fan is controlled by a separate module, called the b... 8.9K subscribers Subscribe 1.6K views 2 years ago how to diagnose fan motor from wiring diagram with blower resistor Network this explains all of the speeds of the fan motor and how the...Aug 24, 2012 · Jeep Master. 21,873 Answers. Well, not exactly. The blower switch gets power from the control panel that gets power from the 25amp fuse in the fuse box. The wire from the fuse box to the control panel is black and tan, the wire from the control panel to the fan switch is yellow and brown. Posted on Aug 24, 2012. Figure 1 If your blower or fan motor runs at full speed regardless of the setting you have it on there is a very good chance your resistor is bad. The resistor is located below the blower motor in the cabin air box (red arrow). Please see our article on blower motor replacement for additional assistance on removing the motor.Jan 8, 2016 · A failed blower motor resistor can cause issues with the operation of the entire heating and air conditioning system. Usually a bad or failing blower motor resistor will produce a few symptoms that can alert the driver of a potential issue. 1. Blower motor stuck on one speed. A common symptom of a faulty blower motor resistor is a blower motor ... On my 1066, though, the blower has a similar wiring setup. The three wires from the motor are indeed the speeds. If you put 12v of power to each one in turn, the motor should run at whatever speed you have powered. One terminal on the switch should have battery power. The other may be for powering an air conditioner unit.Version. Listed below is the vehicle specific wiring diagram for your car alarm, remote starter or keyless entry installation into your 1998-2001 Dodge Ram . This information outlines the wires location, color and polarity to help you identify the proper connection spots in the vehicle. Please be sure to test all of your wires with a digital ...Blower Motor Resistor Wiring Diagrams. A blower motor resistor works by routing power through 1, 2, or 3 in-series resistors. See the blower motor resistor wiring diagrams below to see how it works on each speed. Posted on June 26, 2020 by Rick Muscoplat. eautorepair.net.Administrator. Joined: Nov 2003. Posts: 6,035. Illinois. I found discrepancies in wire colors between the '68 AC wiring diagram and the schematic on the '68 Diagnosis Manual too. For example, the wiring diagram shows a black-orange stripe to the blower motor yet my '68's wiring agrees with the Diagnosis schematic purple wire to the motor.The average replacement cost of a blower motor resistor is between $90 and $175. Expect to spend about $40 to $100 on the part and another $50 to $75 for labor if you can’t perform the replacement yourself. However, you should bear in mind that the most common reason for a bad blower motor resistor is due to a bad fan motor.3Ø WIRING DIAGRAMS 1Ø WIRING DIAGRAMS Diagram ER9 M 3~ 1 5 9 3 7 11 Low Speed High Speed U1 V1 W1 W2 U2 V2 TK TK Thermal Overloads TWO SPEED STAR/DELTA MOTOR Switch M 3~ 0-10V 20V 415V AC 4-20mA Outp uts Diagram IC2 M 1~ 240V AC 0-10V Outp ut Diagram IC3 M 1~ 0-10V 4-20mA 240V AC Outp uts These diagrams are current at the time of publication ...BASIC BLOWER RESISTOR WIRING DIAGRAM (POSITIVE SWITCH CONTROL)Panibagong video na naman ang aking nais ibahagi sa inyo mga bossing. So sa video na ito itutur...Re: heat/AC wiring diagram. « Reply #6 on: April 16, 2008, 03:44:37 PM ». ok heres the diagram you posted. the brown/white wire from the selector to the resistor is yellow on my truck. this wire has power all the time even when the truck is off and when the fan is in the off position which feeds the fan 12V and 1 amp (motor does not operate ...Feb 20, 2019 · Connect the wire harness to the blower motor resistor… and engage the wire harness connector locking tab. To reinstall the glove box, put it in position and turn it slightly sideways… so... Blown heater motor resister, melted speed switch, melted wires in steering column. The Fix: Adding relays in the heater circuit. You will also need to replace your blower motor resistor, and selector switch if you have not already done so. Parts Needed: 4 relays. 10 feet red 12 gauge wire.Aug 3, 2023 · Figure 1 If your blower or fan motor runs at full speed regardless of the setting you have it on there is a very good chance your resistor is bad. The resistor is located below the blower motor in the cabin air box (red arrow). Please see our article on blower motor replacement for additional assistance on removing the motor. Jan 16, 2013 · 4. Remove the 2 screws that secure the blower motor resistor or controller to the heater-AC housing. 5. Remove the blower motor resistor or controller from the heater AC housing. INSTALLATION 1. Install the blower motor resistor or controller to the heater AC housing. The housing is indexed to allow (controller power module) mounting in only one Blower motor wiring diagrams for three or four speed systems. Carmakers use these three common wiring methods to supply power and ground to the blower motor in a manual system using a blower motor resistor.Apr 7, 2014 · miami5th said: If you buy the Mopar kit with the upgraded resistor you have to swap the wire orientation coming from the resistor to the blower motor. I believe it's a green and black wire set. I just focused on the plug that goes into the blower motor. No need to slice and splice to change the wire orientation. Followed these instructions and found a break in the connection between wire and connector in one of the wires of the adaptor. How this came to be, is a mystery but I managed to open the little female metal pin connector at the end of the wire, reattach it with fiddling and some tape en reassembled the thing. Works perfect for now. Ok, I replaced the, ac controller unit, wiring connector, and blower motor. With the new parts, the system is functional however one problem still persists which is: The Blower Resistor heats up like a hot plate when the system is on. I tried both the original resistor and the new one and both had the same overheating problem. 1.Product Spotlight: Blower Motor Resistor (RU631) On most full-size GM trucks and SUVs from 2001–2007, the Blower Motor Resistor has two common failure modes: water damage and excess heat. The GM vehicles are unable to manage condensation. If the duct is clogged, condensation will collect, creating a pool of water that can seep into and flood ...Understanding the Wiring Diagram for a Blower Motor Resistor. To properly understand a wiring diagram for a blower motor resistor, it is important to understand how the components work together. The diagram will show the connection between the board, resistor, switches, and thermal fuse.Blower Wiring Diagram for 2010 F150. I need a blower wiring diagram &/or advise for a 2010 F150, 5.4L, 2009-2014 should be the same. Can't find diagram here or on Google. Most of the time my blower does not work but it comes on about once a week, in high I think but not very strong. I replaced the fan resistor but that didn't help.BLOWER RESISTOR BLOCK WIRING DIAGRAM (NEGATIVE SWITCH CONTROL)Sa video na ito ay ipapakita ko sa inyo ang wiring diagram ng blower resistor block. Kaya't pan...Oct 30, 2010 · made sure the blower fan could spin and made sure no obstructions 2a. cleaned the cabin filters 3. can power up the blower directly with a different power source and it works 4. blower relay checked out okay 5. blower resistor checked out okay 6. downloaded a manual to look at wiring diagrams - where i'm currently at, to see what I could also ... Slide it toward the rear of the vehicle to remove it. Figure 3 The green arrow points to the blower motor resistor and the red arrow points to the blower motor. All testing will be performed at the resistor. Figure 4 Start by connecting your DVOM to the power feed. Connect your red lead to terminal 4.Blower Motor Resistor Wiring Diagram. A wiring diagram will show you where the cables should be connected, removing the need for guesswork. You can avoid making errors if you use a wiring diagram to discover out what wires go where.S. srraviindran Discussion starter · Mar 20, 2018 (Edited) E90, 320d 2012, The a/c blower unit circuit is not receiving signal, checked panel switch, blower resistor, and just wont get voltage. Rechecked ac heater, blower module, no supply reaching.On my 1066, though, the blower has a similar wiring setup. The three wires from the motor are indeed the speeds. If you put 12v of power to each one in turn, the motor should run at whatever speed you have powered. One terminal on the switch should have battery power. The other may be for powering an air conditioner unit.Jul 10, 2008 · Blown heater motor resister, melted speed switch, melted wires in steering column. The Fix: Adding relays in the heater circuit. You will also need to replace your blower motor resistor, and selector switch if you have not already done so. Parts Needed: 4 relays. 10 feet red 12 gauge wire. BASIC BLOWER RESISTOR WIRING DIAGRAM (POSITIVE SWITCH CONTROL)Panibagong video na naman ang aking nais ibahagi sa inyo mga bossing. So sa video na ito itutur...Feb 4, 2022 · The most common causes for AC fan blower motor not working in Ford Fiesta are blown fuse, bad relay, resistor or control module malfunction and faulty blower motor. However, a bad electrical connector or broken wire, or a defect in the climate control unit can also cause the blower motor to stop working. 1. Blower Motor, and Wiring. So, my blower motor took a dump the other day, and I replaced it yesterday. I tried to run it, then the resistor block connector melted. So I replaced that, today and the resistor block got really hot, and the motor still didn't work. I've replaced: resistor block and pigtail, blower relay and pigtail, blower, inside I ...Oct 19, 2010 · Like. abernut Discussion starter · #10 · Oct 21, 2010. That indeed was the correct wire. I plugged it in to the blower, got back in the cab, turned the key and with a little bit of hesitation turned the heater knob to Max. The **** eating grin I had on my face when I heard the blower fire up was priceless.:2thumbsup: A small module was replaced--- I believe it was know on the forums as the blower motor resistor module.. 2023 Traverse LT 3.6L 7,500. 2013 Equinox 3.6L 121,000. 2003 Trailblazer 4.2L 188,000. 2010 Traverse 3.6L 193,000.A. adamjeeps · #3 · Jan 4, 2019 (Edited) Jeannecar said: I would like to hear from anyone who has had their blower motor for the A/C go out along with resistor wire melting. I just had this happen at 42k miles so not under way...cost is $850.00 to fix due to blower motor, resistor wire and harness plug. I was told this happens as the blower ...mentions fuses keep popping, i removed the dash panels to access the blower motor etc, pulled wiring harness out and load tested all wiring coming from blower motor to HVAC controller, all good. have good 12V supply (Pin1) and good Ground (Pin3), at the blower motor connector. pins 4 and 6 only have a max of8.9K subscribers Subscribe 1.6K views 2 years ago how to diagnose fan motor from wiring diagram with blower resistor Network this explains all of the speeds of the fan motor and how the...Jun 19, 2008 · No, the resistor will easily come off and rep-connect. Just trace the red/back from the resistor and you'll find it plugs into the fan motor. That is the easiest part of this repair, the splicing of wires is the hardest. As smith mentioned, pay attention to the wire order so you don't do what I did first. No, the resistor will easily come off and rep-connect. Just trace the red/back from the resistor and you'll find it plugs into the fan motor. That is the easiest part of this repair, the splicing of wires is the hardest. As smith mentioned, pay attention to the wire order so you don't do what I did first.Apr 20, 2020 · OPGI has pictures of both the three-prong blower motor resistor for 1968 with AC # CH31821 ($25) and the four-prong blower motor resistor for 1969-72 with AC # CH31592 ($46) -Frank. 1970 Chevelle Malibu purchased new in 1970. 355 SBC, XE262H cam, Performer RPM heads, MSD HEI, TH200-4R trans, 3.55:1 Posi, digital gauges, QA1 coilovers. Mar 21, 2010 · Hooked the brown wire to the positive battery terminal, the yellow to the negative, I heard the fan spin- so, the fan blower is operational. Step 2. If that works reconnect them. Turn the ignition on. Take the wire, should be yellow, off of the resister on the heater box and ground it. The fan should also spin. Oct 11, 2008 · SOURCE: 1999 expedition 5.4L eddy bauer check fuses,check power and ground at blower motor.if the blower has only one speed it will mean a resistor is shot.an easy test if blower is not working at all is to turn blower on hi and tap on the bottom of blower motor with hammer if the blower motor kicks in then you know the motor is the problem.if the motor still does not work,the wiring to the ... Re: 72 C10 heater/ A/c wiring diagram. Just rebuilt my factory AC and here is what I found - I had the opposite problem than you - my low and med speeds weren't working but high was. The high side is your relay and it is mounted to the heater box behind the glove box. The low and med speeds are resistor related.Re: 72 C10 heater/ A/c wiring diagram. Just rebuilt my factory AC and here is what I found - I had the opposite problem than you - my low and med speeds weren't working but high was. The high side is your relay and it is mounted to the heater box behind the glove box. The low and med speeds are resistor related.Sep 17, 2014 · Wiring diagram for 1999 nissan maxima blower switch. Replaced blower motor resistor but fan for heat and ac works on high only. suspect switch is bad. would like wiring diagram for blower motor switch to test switch to verify its bad. Posted by Anonymous on Sep 17, 2014. Re: heat/AC wiring diagram. « Reply #6 on: April 16, 2008, 03:44:37 PM ». ok heres the diagram you posted. the brown/white wire from the selector to the resistor is yellow on my truck. this wire has power all the time even when the truck is off and when the fan is in the off position which feeds the fan 12V and 1 amp (motor does not operate ...Sep 17, 2014 · Wiring diagram for 1999 nissan maxima blower switch. Replaced blower motor resistor but fan for heat and ac works on high only. suspect switch is bad. would like wiring diagram for blower motor switch to test switch to verify its bad. Posted by Anonymous on Sep 17, 2014. Nov 8, 2018 · Changed blower resistor, pigtail and blower motor and it's still not working. Did the same 14 months ago and it corrected the problem. Not sure if the wires aren't connected correctly or if there coul … The blower motor consists of the blower fan and motor. A sirocco fan has been adopted for the blower fan. Operation. 1. The front body control module (FBCM) turns on the blower relay based on the blower ON signal sent from the climate control unit. 2. When the blower relay turns on, the blower motor fan rotates. 3. The rotation speed of the ...Connect the wire harness to the blower motor resistor… and engage the wire harness connector locking tab. To reinstall the glove box, put it in position and turn it slightly sideways… so...The kit that Toyota recommends is 87138-04070 (resistor) and wiring adapter (82141-04Q80). This resistor has the terminals in a square pattern rather than a line. I'm assuming this is from a 3rd gen and hopefully changes were made to fix the well known issue.3Ø WIRING DIAGRAMS 1Ø WIRING DIAGRAMS Diagram ER9 M 3~ 1 5 9 3 7 11 Low Speed High Speed U1 V1 W1 W2 U2 V2 TK TK Thermal Overloads TWO SPEED STAR/DELTA MOTOR Switch M 3~ 0-10V 20V 415V AC 4-20mA Outp uts Diagram IC2 M 1~ 240V AC 0-10V Outp ut Diagram IC3 M 1~ 0-10V 4-20mA 240V AC Outp uts These diagrams are current at the time of publication ...anythingonwhlz Discussion starter · Jan 3, 2012. Happy New Years to all. Im in the middle of trying to figure out why my heater is not blowing. So I figure Id check the wiring on it. So can someone please post a complete wiring schematic of the heater/blower fan set-up from the fuse box to the switch to the fan motor?Dec 27, 2014 · # 1 low speed .Looking at a wiring diagram I would think that impossible . # 1 position for low speed would need to go through all the resistors in the resistor pack , which would mean all others good . # 5 high speed doesn't use resistors . uses a relay an direct B+ to the blower motor . 7. 72ElCamino · #3 · Jan 15, 2009. Re: 71 blower motor resistor wiring. grumpyschevelle said: I was able to find a previos thread that mentioned the relay wiring and what wire went to what terminal blade. Im still at a loss on the wiring that goes to the blower motor resistor though.Once the cover is off there is an air duct right in front of the blower motor and the resistor, but it isn't necessary to remove that unless you choose to do so for ease of access. There are two 7mm bolts holding the resistor in (Caution! please tell your readers to only tighten these bolts HAND tight when replacing them.Sep 8, 2022 · Understanding the Wiring Diagram for a Blower Motor Resistor. To properly understand a wiring diagram for a blower motor resistor, it is important to understand how the components work together. The diagram will show the connection between the board, resistor, switches, and thermal fuse. All control of the blower operation is done using the ground side of the circuit. You should always have 12 volts at the brown wire of the blower connector. You won't get 12 volts by metering the brown and orange leads, if the ground is defective. There aren't any HVAC grounds in the ground point on the left side.Jan 8, 2016 · A failed blower motor resistor can cause issues with the operation of the entire heating and air conditioning system. Usually a bad or failing blower motor resistor will produce a few symptoms that can alert the driver of a potential issue. 1. Blower motor stuck on one speed. A common symptom of a faulty blower motor resistor is a blower motor ... Aug 24, 2012 · Jeep Master. 21,873 Answers. Well, not exactly. The blower switch gets power from the control panel that gets power from the 25amp fuse in the fuse box. The wire from the fuse box to the control panel is black and tan, the wire from the control panel to the fan switch is yellow and brown. Posted on Aug 24, 2012. Feb 4, 2022 · The most common causes for AC fan blower motor not working in Ford Fiesta are blown fuse, bad relay, resistor or control module malfunction and faulty blower motor. However, a bad electrical connector or broken wire, or a defect in the climate control unit can also cause the blower motor to stop working. 1. Blower Motor Resistor Wiring Diagrams. A blower motor resistor works by routing power through 1, 2, or 3 in-series resistors. See the blower motor resistor wiring diagrams below to see how it works on each speed. Posted on June 26, 2020 by Rick Muscoplat. eautorepair.net.4. Remove the 2 screws that secure the blower motor resistor or controller to the heater-AC housing. 5. Remove the blower motor resistor or controller from the heater AC housing. INSTALLATION 1. Install the blower motor resistor or controller to the heater AC housing. The housing is indexed to allow (controller power module) mounting in only oneBlown heater motor resister, melted speed switch, melted wires in steering column. The Fix: Adding relays in the heater circuit. You will also need to replace your blower motor resistor, and selector switch if you have not already done so. Parts Needed: 4 relays. 10 feet red 12 gauge wire.The heater blower motor stops working ? Testing the electrical circuit would be the proper way to diagnose . Looking at a wiring diagram an using a DMM - digital multi-meter , an doing amp draw test on the blower motor . The PRND321 an blower motor probably share a ground or power point . Looking at a wiring diagram for both circuit's would ...Jun 14, 2016 · so i have replaced the resistor and wiring harness and ac worked great for 3 days, now nothing. i replaced the blower motor and still nothing. i am showing 12-15v at each fan setting, 0v through the ground, and 12-15v from the resistor to the blower motor through the black wire. all fuses are appear to be ok and i am at a loss. The most common causes for AC fan blower motor not working in Chevy Malibu are blown fuse, bad relay, resistor or control module malfunction and faulty blower motor. However, a bad electrical connector or broken wire, or a defect in the climate control unit can also cause the blower motor to stop working. 1.On a 66 heater (no ac car) the blower fan power is fed via the orange wire from the heater motor. That wire goes back through the bulkhead connector, so check and clean that connection. From there it goes to the heater blower resistor, inside the car, on top of the heater box under the glove box.so i have replaced the resistor and wiring harness and ac worked great for 3 days, now nothing. i replaced the blower motor and still nothing. i am showing 12-15v at each fan setting, 0v through the ground, and 12-15v from the resistor to the blower motor through the black wire. all fuses are appear to be ok and i am at a loss.Aug 28, 2020 · looking at diagram 68/69 diagram ( 70 maybe the same ? ), High speed is a straight feed from the switch not going through the resistor block, just like 71/74 are. Its spliced into the resistor block just to use that wire to source the output from resistor block to the blower with the speed selected using just one wire for the blower. Mar 21, 2010 · Hooked the brown wire to the positive battery terminal, the yellow to the negative, I heard the fan spin- so, the fan blower is operational. Step 2. If that works reconnect them. Turn the ignition on. Take the wire, should be yellow, off of the resister on the heater box and ground it. The fan should also spin. Wiring diagram for 1999 nissan maxima blower switch. Replaced blower motor resistor but fan for heat and ac works on high only. suspect switch is bad. would like wiring diagram for blower motor switch to test switch to verify its bad. Posted by Anonymous on Sep 17, 2014.Blower resistors are resistors which are used to control the fan speed of automotive blowers. The fan speed can be changed either by switching the blower resistor resistance mechanically using a rotating lever, or electronically by the air conditioning system. The change in resistance then limits the current through the motor, which dictates ... 3Ø WIRING DIAGRAMS 1Ø WIRING DIAGRAMS Diagram ER9 M 3~ 1 5 9 3 7 11 Low Speed High Speed U1 V1 W1 W2 U2 V2 TK TK Thermal Overloads TWO SPEED STAR/DELTA MOTOR Switch M 3~ 0-10V 20V 415V AC 4-20mA Outp uts Diagram IC2 M 1~ 240V AC 0-10V Outp ut Diagram IC3 M 1~ 0-10V 4-20mA 240V AC Outp uts These diagrams are current at the time of publication ...Jan 14, 2009 · 7. 72ElCamino · #3 · Jan 15, 2009. Re: 71 blower motor resistor wiring. grumpyschevelle said: I was able to find a previos thread that mentioned the relay wiring and what wire went to what terminal blade. Im still at a loss on the wiring that goes to the blower motor resistor though. Resistor —Heater Blower Motor Switch Removal . Remove the battery (10655) ; refer to Section 414-01 . Remove the battery tray. Remove the screws. Remove the battery tray. Disconnect the heater blower motor switch resistor connector. Remove the heater blower motor switch resistor (18591). Remove the two screws.Jul 10, 2018 · A. adamjeeps · #3 · Jan 4, 2019 (Edited) Jeannecar said: I would like to hear from anyone who has had their blower motor for the A/C go out along with resistor wire melting. I just had this happen at 42k miles so not under way...cost is $850.00 to fix due to blower motor, resistor wire and harness plug. I was told this happens as the blower ...
To install: Align and install the blower motor into the HVAC housing. Install the three screws that secure the blower motor to the HVAC housing. Tighten the screws to 20 inch lbs. (2.2 Nm). Connect the wire harness connector to the blower motor. Reconnect the battery negative cable.. Mandt bank atm check deposit limit
On a 66 heater (no ac car) the blower fan power is fed via the orange wire from the heater motor. That wire goes back through the bulkhead connector, so check and clean that connection. From there it goes to the heater blower resistor, inside the car, on top of the heater box under the glove box.Aug 3, 2023 · The blower motor resistor controls the fan speed of your vehicle’s blower motor. A faulty blower motor resistor hampers the operation of the heating and air conditioning system. If your air-conditioning fan only works at some speeds but not at others, then the resistor might be suspect. Heater blower motor randomly stopped working. Put 12v to the fan and it spins. Bought a replacement fan with a new resistor module Tried different climate control module Checked all wiring from fan to climate control module to fuse box. All is good and getting 12v. Checked fuses and relays 2007 GTIAdministrator. Joined: Nov 2003. Posts: 6,035. Illinois. I found discrepancies in wire colors between the '68 AC wiring diagram and the schematic on the '68 Diagnosis Manual too. For example, the wiring diagram shows a black-orange stripe to the blower motor yet my '68's wiring agrees with the Diagnosis schematic purple wire to the motor.Aug 14, 2019 · The kit that Toyota recommends is 87138-04070 (resistor) and wiring adapter (82141-04Q80). This resistor has the terminals in a square pattern rather than a line. I'm assuming this is from a 3rd gen and hopefully changes were made to fix the well known issue. Jul 10, 2018 · A. adamjeeps · #3 · Jan 4, 2019 (Edited) Jeannecar said: I would like to hear from anyone who has had their blower motor for the A/C go out along with resistor wire melting. I just had this happen at 42k miles so not under way...cost is $850.00 to fix due to blower motor, resistor wire and harness plug. I was told this happens as the blower ... Aug 22, 2023 · The average replacement cost of a blower motor resistor is between $90 and $175. Expect to spend about $40 to $100 on the part and another $50 to $75 for labor if you can’t perform the replacement yourself. However, you should bear in mind that the most common reason for a bad blower motor resistor is due to a bad fan motor. 2003 dodge durango blower motor resistor wiring diagram. Clicking this will make more experts see the question and we will remind you when it gets answered. Disconnect and isolate the battery negative cable. Open the glove box. Flex both sides of the glove box bin inward near the top far enough for the rubber glove box stop bumpers to clear the ...Re: 72 C10 heater/ A/c wiring diagram. Just rebuilt my factory AC and here is what I found - I had the opposite problem than you - my low and med speeds weren't working but high was. The high side is your relay and it is mounted to the heater box behind the glove box. The low and med speeds are resistor related.Jun 14, 2016 · so i have replaced the resistor and wiring harness and ac worked great for 3 days, now nothing. i replaced the blower motor and still nothing. i am showing 12-15v at each fan setting, 0v through the ground, and 12-15v from the resistor to the blower motor through the black wire. all fuses are appear to be ok and i am at a loss. Nov 2, 2015 · On a 66 heater (no ac car) the blower fan power is fed via the orange wire from the heater motor. That wire goes back through the bulkhead connector, so check and clean that connection. From there it goes to the heater blower resistor, inside the car, on top of the heater box under the glove box. How To Replace A Blower Motor Resistor. Find the resistance for the blower motor. Now you must unplug the resistor from the housing and take the harness off. The blower motor resistor will simply slip out of the HVAC enclosure once the wiring harness has been disconnected. The new resistor can now be installed.Re: 72 C10 heater/ A/c wiring diagram. Just rebuilt my factory AC and here is what I found - I had the opposite problem than you - my low and med speeds weren't working but high was. The high side is your relay and it is mounted to the heater box behind the glove box. The low and med speeds are resistor related.There is a plug in jumper harness avaliable for installing a later model blower motor into an earlier 1992-2004 car, part #4W7Z-14A411-B (WT-56853). You could also cut off your old wiring pigtail and splice on a new one using kit 3U2Z-14S411-YBA (WPT-605) instead..