Question about 1999 GMC Jimmy

Open Question

1999 GMC Jimmy only blows hot air. Changed out the a/c heater control panel, put freon in but it only blows hot air. Even with just vent on pulling in outside air, it's too hot. Need a/ please!

Posted by on


6 Suggested Answers

  • 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.
Good luck!

Posted on Jan 02, 2017

  • 9 Answers

SOURCE: 94 GMC Jimmy heater fan not working

if you hear the fans blowing and no heat is coming
then you mite have to replace the heater.

before you try to replace the heater talk to Lords

Posted on Dec 04, 2008


SOURCE: 2001 gmc jimmy engine warm but heater blows cold air

Disconnect the heater hoses from the water pump and the intake manifold. Get a compressor and blow out the hose (put the air hose into the the hose that came off the mainfold. then flush the system and replace the antifreeze.

Posted on Dec 12, 2008

  • 6 Answers

SOURCE: heater goes from hot to cold


Posted on Dec 20, 2008

  • 79092 Answers

SOURCE: how do you remove a heater core from a 1999 gmc

The instrument panel carrier is designed not only to provide access to parts through removal of the carrier components, but the carrier will also tilt downward as a complete assembly to allow access from the top. If this is desired, remove the retainer screws along the top and bottom of the carrier assembly (refer to the figure). The instrument panel will then tilt as an assembly into the cab. It is necessary to unbolt and lower the steering column from the carrier to allow for maximum movement of the instrument panel. OK you'll find and remove two screws in each of the defrost vents, that done now start on the passenger side by removing the side kick pad, 4 screws, now remove all the screws along the bottom of the dash, there should be 8- 1/4 head screws and three black plastic peaces will come out once you've got them all out, a long one on the passenger side, one under the steering wheel, and one small one by the fuse box, now there is one more panel to take off right under the calum you need to do this to get to your calum nuts, Oh the park brake cable needs to come off there's spring on the cable by the little lead ball on the end you need to compress it to get it over the fork in there, you'll see. OK now you have to locate four 3/8 head screws along the bottom one in each corner of the dash, one in the middle, and fourth one is up by the sheering calum nuts the nut close to the passenger side, now if yours has a tray in front of the center Counsel it is a good time to remove it three Philips screws and unplug the wires, I took this out because I need to wash all the anti freeze out of small duct pieces and the foam inside OK now turn the key on and shift the shifter to low to get the handle out of your way for later, ( UPDATE remove the plastic shifter indicator cable, you'll find it clipped on the part of the calum that moves as you shift, it will just push off, it should be on the right side under the calum nut if you don't the indicator won't work right ) remove the two steering calum nuts and pull the the calum down, time to move to the passenger side again, I did take the radio out but I found I didn't need to it will cut down on the weight though. OK now start to lift and pull and just keep working it out If you need a picture of where the heater core is and what it looks like send me a e mail at windwalker.xc@gmail.comand I'll send you a picture I took of mine, anyways keep working it out till it's about a foot and a half out, now if it's not coming out check to see if a wire is holding you back I had a white one from the firewall and the wires for the computer needed to be worked and loosened a bit. OK now it's time to go after the heater core, the heater core cover has six screws holding it on, three up top and three on the bottom none are hid like some say in the forums, now move that cover to your right to brake it free, the foam on the left side is what is holding you back just rip it on the top and bottom fix it later, with that cover out of the way you should see the core now, on the sides you'll see a steel strap each strap has two screws holding it in place, remove them. OK now go out and under the hood, I found just cutting the hoses off at the core pipes worked for me if yours come off easy do that mine were not coming off, you will see a bracket in between the to pipes it is held there with a small screw, remove this screw then the bracket, because it won't pull through the fire wall, trust me, jam some rags in the heater core tubes so anti freeze doesn't spill out as you pull it through the fire wall, time to go back into the cab now. OK now just remove the old core and put the new one in, go out under the hood put your bracket back on, put in the screw then the hoses, go back to the cab and replace the heater core cover, put in your six screws, Now with the cover back start working the dash back into place, remember any wires you unplugged need to be replugged Eh. once the dash is in place I put the top screws in first, the ones up top at the defrost ducts, not all the way in mind you, because you'll need to move your dash around a bit to make sure all the screws on the the bottom line first

Posted on Oct 23, 2009

  • 2 Answers

SOURCE: heater blower motor sometimes works

The problem is usually with the motor itself. If the blower will not come on, tap it with a hard object to see if it works. If it does, the problem is in the motor and it needs to be replaced. Many times it is a result of weak springs holding the brushes to the armature commutator.

Posted on Jul 29, 2010

Add Your Answer

Uploading: 0%


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



Related Questions:

2 Answers

1999 gmc jimmy heater runs hot when turned all the way up but runs cold if turned down even a little ?

will be this heater mixer valve its vacuum operated

could be a vacuum leak or faulty valve



Oct 18, 2016 | 1999 GMC Jimmy

1 Answer

There is hot air coming out of vents at all times in my 1998 jimmy

Sounds like you have a bad heater door actuator.

May 31, 2014 | 1998 GMC Jimmy

1 Answer

1999 temperature control will not regulate heat/air

This is likely caused by a failed or jammed electric air temerature control blend door actuator and or a warped and jammed blend door.

May 18, 2012 | 1999 Chevrolet Blazer

1 Answer

I have a 1999 Jimmy that I bought used in the middle of winter and never noticed any issue with the heat. Now that it is getting warmer I am roasting all the time! I have the fan off and even when I put...

you could try and pull out the heater controle panel from the dash if it is cable opperated check to make sure the cable is attatched an not broken, if it's vaccum operated you may need to replace the vaccum lines.

Mar 26, 2011 | 1995 GMC Jimmy

1 Answer

Heating Unit problem

check the fuse and the wires.

Jun 19, 2010 | 1999 GMC Jimmy

2 Answers

Vents blowing constant cold air...told it was the blend door on my 1999 GMC Jimmy ....replaced thermostat.....flushed system and replaced cracked radiator....heater coil is not leaking. A/C is a seperate...

Its more than likely the blend door not moving to the heat position. I'm not familiar with the location of the blend door in the 1999 GMC jimmy, since I'm not a mechanic and don't have a manual on that vehicle. If you can get to the blend door housing you might be able to move it physically.

Sep 13, 2017 | 1999 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

1998 Town Car A/C Blows Hot Air But Is Charged Up

Hi - There may be 2 separate problems. On my 1991 Lincoln Town Car, there is a Thermal Blower Lockout sensor that disables the heater from blowing until the engine temperature reaches a specific temperature. This way if you have vent or floor settings and 90 degrees set and it is winter, you won't get blasted with cold air. When the vehicle warms up, the TBL circuit enables the climate control to blow the hot air. If you use the flr/def instead of the floor or vent control, the TBL should not prevent the heater from working even with a cold engine. On my car, the TBL went bad and always prevented hot air from blowing on the floor and vent settings, even when the engine was hot. Another thing to check is a thermal limitor resistor. It is designed to cut off the blower at very hot temperatures, except if the blower fan is in the hi setting.

As far as the A/C is concerned, can you verify if the clutch is engaging or not? A rapid cycling of the clutch is an indication of low freon. If you are absolutely sure that you are fully charged on freon, I think there are 2 possible causes: (1) Bad pressure switch on the accumulator is indicating low freon that is telling the compressor not to work; (2) a blocked orifice tube.

Aug 02, 2009 | 1991 Lincoln Town Car

2 Answers

1999 Suburban, A/C on warm air from front vents, cold air in rear

The car uses the same freon in the front as it does in the rear. If the rear a/c is working, you either have a plugged evaporator in the front unit, or perhaps a bad heater switch. Try switching the heater to hot and see if it blows even warmer air from the front vents. If so, the heater switch is working and then it sounds like a plugged evaporator or maybe a plugged orifice tube. That is a good place to start looking. Hope this helps.

Jul 07, 2009 | 1997 Chevrolet Suburban

1 Answer

1999 gmc jimmy. The heater control is stuck on HOT.

if the knob wont move replace it junk yard may have used part but if it moves and hot air keeps blowing out u may need a servo that opens and closes heater box door under dash i dont think that trucks system works off vacuum but if it does it probably electronic related problem inquire junk/salvage yard about knob and servo for heater box door and problem it may be common and u may get info if he,s a nice guy

Mar 28, 2009 | 1999 GMC Jimmy

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

Related Topics:

184 people viewed this question

Ask a Question

Usually answered in minutes!

Top GMC Experts


Level 3 Expert

79077 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22326 Answers

Ronny Bennett Sr.
Ronny Bennett Sr.

Level 3 Expert

6927 Answers

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

Answer questions

Manuals & User Guides