Question about 1999 GMC Jimmy

1 Answer

I have a 99 gmc jimmy the heater motor works on settin 3 4 but not on 1 2 , i have changed the heater control switch but still thesame thing i have also changed a relay that is under the hood on the firewall that is close to the heater airbox still no difference any other things i could check ? i also thought it could be the fuse relay center but it was not that i have a complete 99 blazer for parts

Posted by on

1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 20 achievements.


    An expert that got 10 achievements.


    An expert that got 5 achievements.

  • GMC Master
  • 17,970 Answers

I'm assuming that the blower isn't work in LOW, then with blower control speed at Low, you have no power supply to the yellow wire. Let ma know the following:
1. Do you have power at the Tan wire when blower speed is set at M1?
2. Do you have power at the Light Blue wire when blower speed is set st M2?
3. Does applying battery voltage to the terminal of the resistor at the yellow wire work the blower at low speed?
4. Did you test the HTR fuse ( 25A) in the fuse box?

If you have power on the brown wire coming from the heater 25amp fuse when key is On and when you switch to low the yellow wire should have power-Is this happening if not were right back with HVAC control module. Now if yellow has power ,blower motor should come On-if not-check and test the ground pointG201 at right side of dash.

Keep us uodated.

Posted on Nov 11, 2010

1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

1999 gmc jimmy cant get heat, heater core fine, can get heat on floor but nothing when switch to vent. can see actuators working. ambient temp sensors resistance on 1 one passenger side no resistance

just went through the same thing in my 99 silverado.could see acctuators working also,but i still had to change" mode" acctuator as it was only operating on 2 modes not all 5

Nov 19, 2016 | GMC Cars & Trucks

1 Answer

Question about auto 4wd on my 99 GMC Jimmy

no not normal. check center of firewall the is a switch with 3 vacuum line CHECK THEM ALL this is your 4wd selector. if thats okay you might need the switch on the front trasfer case about $20 just unscrews easy fix.

Dec 25, 2013 | 1999 GMC Jimmy

1 Answer

1998 Jimmy with electrical controls for temperature. Replaced Themostat, Flushed heater core, replaced damaged vacuum lines. Vehicle produces heat to heater core but only luke warm interior temp. Rotated...

Suggestion: see if the blend door opens or closes completely to allow all air through the heater core. To see the blend door moving, remove the panel that says "Cut here for service" under the hood along the firewall. I have a 99 Bravada where the blend door keeps moving back and forth constantly. Changed the blend door actuator but still keeps moving. The air inside is only warm since the door keeps allowing bypassed air through.

Jan 04, 2011 | 1998 GMC Jimmy

2 Answers

How to change heater core on a 97 jimmy

when i turn on my heater it kick out after a few min then come back on or sometimes not at all on my 97 jimmy 4x4

Jul 26, 2010 | 1997 GMC Jimmy

1 Answer

I have a 99 GMC Jimmy with the 4 wheel drive. I

check fuse and relay to switch if power to switch retest switch new doesnt mean not defective if no power check connections and wiring for damage or breaks

Dec 02, 2009 | 1999 GMC Jimmy

2 Answers

Heater won't blow air

check the control switch and the motor. you can remove the fan motor and jump it straight to 12v and see if the motor is faulty. if not than more likely will be the control switch. check fuse and relay also.

Nov 14, 2009 | 1997 GMC Jimmy

1 Answer

My ac blows hot, it worked a few times after i changed out the ac control switches, blowing cold then hot when changed, anly worked for a few cycles, the does the same

Change the temp door actuator motor on the bottom near the center.It is a flat motor that is mounted under the ac/heater box.

Nov 02, 2009 | 1999 GMC Jimmy

2 Answers

4x4 not shifting into high

hi how are you doing? just had same problem with by gmc i replaced the transfurcase motor and it works fine. the electric motor moves the shifter in your transfurcase from 4hi to 4lo and 2hi.there is only 3 things that operate your 4x4 the switch the motor and the control modgual.

Jan 28, 2009 | 1994 GMC Jimmy

1 Answer

Heater blower doesn't work all the time,1995 gmc jimmy

change the blower motor. my 94 did the same thing for 2 weeks b 4 dying

Dec 22, 2008 | 1995 GMC Jimmy

Not finding what you are looking for?
1999 GMC Jimmy Logo

Related Topics:

87 people viewed this question

Ask a Question

Usually answered in minutes!

Top GMC Experts


Level 3 Expert

75817 Answers


Level 3 Expert

1311 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22156 Answers

Are you a GMC Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides