HVAC Control Head

I recently purchased a 2003 Pontiac Grand Prix GT. I took it into service and they indicated the HVAC Control Head might be bad. This may be causing the lights to go off / on and possibly when I switch modes of where the air comes out that it does not work.

As a suggestion, they suggested I could try to find this head at a junk yard and do it myself, but have no idea how to start. Basically my main concern is how do I get the old HVAC Control Head off. With cars (at least with me), its not apparent of how to undo stuff (e.g., screws that unscrew to take it apart, fix it and put it back together).

Any suggestions / guidance on above would be greatly appreciated.

Shawn

Can you be more specific on your problem? What blower speed positions are not working, if any? Before yanking the control head and possibly wasting money there are other possibilities: blower motor, blower motor resistor/control module, and in a worse case scenario a defective ignition switch assembly could cause the problem especially since you mentioned affecting the headlights.

Do you have a manual HVAC system or digital climate controls?

Thanks for the reply.

I have the dual temperature control (not digital)

When I switch from Defrost/Floor to Floor, there is still quite a bit of air coming out of the Defrost. The speeds all seem to be working. Its the flow of the air that I seem to be having trouble with.

With the light (not the headlights - sorry about that), it is the light that is above the A/C button that notes if the A/C is on or off. It flickers off/on when the A/C is on.

I also have a separate problem with the radio where the time and station LCD displays sporadically. Everything works, its just the LCD doesn't always display the time and station. Its very sporadic when it works.

Shawn

I have a 2001 gtp se with the same problem , but my fan only works on number 5 , 1-4 has nothing , can you tell me what needs to be fixed or looked at ? Thanks !

Thanks for the reply.

I have the dual temperature control (not digital)

When I switch from Defrost/Floor to Floor, there is still quite a bit of air coming out of the Defrost. The speeds all seem to be working. Its the flow of the air that I seem to be having trouble with.

With the light (not the headlights - sorry about that), it is the light that is above the A/C button that notes if the A/C is on or off. It flickers off/on when the A/C is on.

I also have a separate problem with the radio where the time and station LCD displays sporadically. Everything works, its just the LCD doesn't always display the time and station. Its very sporadic when it works.

Shawn

Thanks for the explanation. The head unit controls door actuators both vacuum and electrical so it will need to be removed for troubleshooting. Probably a good idea to make sure the electrical connectors on the head unit and radio are tight. The original diagnosis was probably correct. Also with it removed you can check the vaccum lines to certain actuators. If you remove the glovebox door you should be able to see the defrost actuator to the left.

To get to everything you'll need the remove the plastic dash bezel just like getting to remove the radio. The radio with the LCD problem sounds like an internal electronic problem (LCD driver). There are backlight lamps but I don't think that's the problem.

Thanks for the help. Greatly appreciate it. Only have one question.

I've never done this before. You indicated what to remove and what to do, but my problem is I don't know how to do this. For example, I just rebuilt parts of our ice maker among other things. I could see where the screws were and how to take it apart and put it back together. With a car, that is where I am stumped. At least for me its not something that I can easily see of how to get started (e.g., where are the screws to take out the HVAC control head) so I can take out the unit.

I hope I'm explaining myself correctly.

Shawn

Checkout link below. It should give you an idea how to go about it.

http://www.carstereohelp.com/stereoremovalPontiacGrandPrixSt2.htm

My problem is similar, i have a 2002 grand prix gt, and the climate control is the non-digital 2 zone set up. again today the first big winter storm, no FAN controls, the dealer has replaced this unit as defective 2 times already, this is the 3rd POS unit. iwas wondering can i just replace it with the digital version i seen a few on ebay and since my warranty is up i will not take it back to the dealer?
i think the model number of the digital is model # 10435239

thanks
Michael

My problem is similar, i have a 2002 grand prix gt, and the climate control is the non-digital 2 zone set up. again today the first big winter storm, no FAN controls, the dealer has replaced this unit as defective 2 times already, this is the 3rd POS unit. iwas wondering can i just replace it with the digital version i seen a few on ebay and since my warranty is up i will not take it back to the dealer?
i think the model number of the digital is model # 10435239

thanks
Michael

I've never heard of a successful conversion from manual to digital but you never know. Other than replacing the head unit, the you'll need the digital system's blower motor. They are not the same and the blower motor resistor is replaced with a blower motor control module. Plus wiring would need modification to connect everything and addition of temperature sensors. The AC controls interface is different including hookups to compressor, vent actuators, temperature actuators and vacuum control.

It sounds like you may need another manual head unit.

I've never heard of a successful conversion from manual to digital but you never know. Other than replacing the head unit, the you'll need the digital system's blower motor. They are not the same and the blower motor resistor is replaced with a blower motor control module. Plus wiring would need modification to connect everything and addition of temperature sensors. The AC controls interface is different including hookups to compressor, vent actuators, temperature actuators and vacuum control.

It sounds like you may need another manual head unit.

im glad i asked i think you are right, do you knnow if these fan control switches are just junk or whats the deal i have heard of so many of these going bad. i will order the new manual unit right now.

thanks
Michael

im glad i asked i think you are right, do you knnow if these fan control switches are just junk or whats the deal i have heard of so many of these going bad. i will order the new manual unit right now.

thanks
Michael

The '97 - '99 manual units seemed to be more reliable. From what I understand from 2000 and up GM started having these units manufactured in Mexico at the Delphi plants. Maybe it is a quality control issue. Also with the head unit out it would be a good idea to check the wiring at the electrical connectors and make sure the ground(s) is good. Also inspect the blower motor resistor and blower motor assembly. Good luck!

The '97 - '99 manual units seemed to be more reliable. From what I understand from 2000 and up GM started having these units manufactured in Mexico at the Delphi plants. Maybe it is a quality control issue. Also with the head unit out it would be a good idea to check the wiring at the electrical connectors and make sure the ground(s) is good. Also inspect the blower motor resistor and blower motor assembly. Good luck!


is there a way to jumper some wires behind the fan dial to manually get the fan to run so that the car will have heat unntil the new unit arrives?

thanks
Michael

is there a way to jumper some wires behind the fan dial to manually get the fan to run so that the car will have heat unntil the new unit arrives?

thanks
Michael

Are you getting illumination and other controls on the head unit when ignition is in run? Need to be certain the 12v is there. It can be done but not recommended unless you know the blower and resistor are good for sure.

Have you checked fuses: HVAC CTRL, HVAC HI & DIC/HVAC. They will be located in the engine compartment fuse box and passenger side cabin fuse box.

You'll need a GM Grand Prix wiring diagram for reference.

Thank you for the replies and help.

Are you getting illumination and other controls on the head unit when ignition is in run? Need to be certain the 12v is there. It can be done but not recommended unless you know the blower and resistor are good for sure.

Have you checked fuses: HVAC CTRL, HVAC HI & DIC/HVAC. They will be located in the engine compartment fuse box and passenger side cabin fuse box.

You'll need a GM Grand Prix wiring diagram for reference.

agreed yes the lights work, in fact the damn thing started working again. but it is still acting funny... same symptoms last time when the control panel needed replaced, so i have one on the way.

thanks for all your help!
Michael

Michael:

I was just curious how you go about purchasing a new HCAC Contrl Head and the costs. If I do the work myself, I was hoping for a little guidance. Did you also check at a local junk yard? I was thinking I might be able to find one where a car was damaged on the back and the unit might be OK.

Shawn

Michael:

I was just curious how you go about purchasing a new HCAC Contrl Head and the costs. If I do the work myself, I was hoping for a little guidance. Did you also check at a local junk yard? I was thinking I might be able to find one where a car was damaged on the back and the unit might be OK.

Shawn

I bought mine on ebay for 44 bucks i think, and im not really sure what they cost at the dealer. but they are super easy to install, they come out and go in just like a radio replacement.

Michael

Michael:

Thanks. The dealer cost was around $325 (I think). I found one at a salvage yard for $85 and had a six month warranty.

Sound's like its pretty easy to put in. Basically remove the cover, remove the wires and bolts and put a new one in.

Thanks

Shawn

Wow i figured they would screw you out a at least a 150, wow... i will tell you that i will never buy another grand prix again... i had to replace the fuel pump last year too which was a dealer only part 450.00 plus labor 170.00.... and that was a family mechanic... the dealer supposidly could finnd nothing wrong with the car.

oh well its almost paid off time to sell it and find something more reliable i think...

Michael

Michael:

Thanks. The dealer cost was around $325 (I think). I found one at a salvage yard for $85 and had a six month warranty.

Sound's like its pretty easy to put in. Basically remove the cover, remove the wires and bolts and put a new one in.

Thanks

Shawn

Michael:

Thanks. The dealer cost was around $325 (I think). I found one at a salvage yard for $85 and had a six month warranty.

Sound's like its pretty easy to put in. Basically remove the cover, remove the wires and bolts and put a new one in.

Thanks

Shawn

Hey here is another one for 49.00 if you havnt bought yours yet!

http://cgi.ebay.com/ebaymotors/2001-2003-Pontiac-Grand-Prix-Climate-Control-Dual-Zone_W0QQcmdZViewItemQQcategoryZ33545QQitemZ801912 4130QQrdZ1

Hey i just tried the new control unit and nothing no fan response. where do i find the blower motor and resistor? the fuses undner the hood are all good!???

thanks
Michael

The '97 - '99 manual units seemed to be more reliable. From what I understand from 2000 and up GM started having these units manufactured in Mexico at the Delphi plants. Maybe it is a quality control issue. Also with the head unit out it would be a good idea to check the wiring at the electrical connectors and make sure the ground(s) is good. Also inspect the blower motor resistor and blower motor assembly. Good luck!

Hey i just tried the new control unit and nothing no fan response. where do i find the blower motor and resistor? the fuses undner the hood are all good!???

thanks
Michael

On the passenger side of the dash underneath. Remove the kickpanel and then remove 3 5.5mm bolts holding fan up into the HVAC housing. BMR is in the back....see pic below:


http://i5.photobucket.com/albums/y186/lizzywiz/bmr02.jpg

On the passenger side of the dash underneath. Remove the kickpanel and then remove 3 5.5mm bolts holding fan up into the HVAC housing. BMR is in the back....see pic below:


http://i5.photobucket.com/albums/y186/lizzywiz/bmr02.jpg

awesome picture thanks, i think i found it, is there a way to test it? i cant imagine anything else, all the fuses are good, there is heat jujst no fan.

[QUOTE=bnaylor3400]On the passenger side of the dash underneath. Remove the kickpanel and then remove 3 5.5mm bolts holding fan up into the HVAC housing. BMR is in the back....see pic below:


awesome picture thanks, mine however looks very different, lemme grab a pic of it.. BRB

here is what im lookin at:
http://i13.photobucket.com/albums/a300/weaselphd/DSC03473.jpg

http://i13.photobucket.com/albums/a300/weaselphd/DSC03472.jpg

http://i13.photobucket.com/albums/a300/weaselphd/DSC03471.jpg

awesome picture thanks, mine however looks very different, lemme grab a pic of it.. BRB

It's still looks basically the same. Pontiac redesigned the blower motor resistor and harness to it. Yours shows the 2002 model version. The pic I showed was with the blower motor already removed but it's still in a similar spot. The parts listings still call it a blower motor resistor if you have the non-digital dual climate control system.

It's still looks basically the same. Pontiac redesigned the blower motor resistor and harness to it. Yours shows the 2002 model version. The pic I showed was with the blower motor already removed but it's still in a similar spot. The parts listings still call it a blower motor resistor if you have the non-digital dual climate control system.

Ok hopefully my local Murrays will sell these resistors, i will pick one up tomorrow, will i have to remove the blower motor as you did, im still unsure where it is on my 2002, but i suppose once i buy the new one ill just look for the same part under the dash.

thanks so much for all your replies!! i hope this works...

Michael

Ok hopefully my local Murrays will sell these resistors, i will pick one up tomorrow, will i have to remove the blower motor as you did, im still unsure where it is on my 2002, but i suppose once i buy the new one ill just look for the same part under the dash.

thanks so much for all your replies!! i hope this works...

Michael

The reason why you need to remove the blower motor is for access to get to the screws that hold the blower motor resistor. Once properly loosened the BMR will drop down after you pull a little forward towards you.

Before you get the resistor what were your symptoms? Does your blower work in position 5 (high)?

Also I forgot to mention, I recall you will need to undo that guide plate that holds the wiring and vacuum lines because it will be in the way. It's in one of your pics. The blower motor should have 3 screws/bolts, size 5.5mm holding it. Good luck and hope you get it resolved.

The reason why you need to remove the blower motor is for access to get to the screws that hold the blower motor resistor. Once properly loosened the BMR will drop down after you pull a little forward towards you.

Before you get the resistor what were your symptoms? Does your blower work in position 5 (high)?

Also I forgot to mention, I recall you will need to undo that guide plate that holds the wiring and vacuum lines because it will be in the way. It's in one of your pics. The blower motor should have 3 screws/bolts, size 5.5mm holding it. Good luck and hope you get it resolved.


There is absolutely NO fan nothing on 1,2,3,4 or 5... there is radiant heat of course but NO FAN at all. i checked the fuses under the hood and in the glove box they are all good... i also tried the new Control unit and nothing on all 5 fan settings.

any more suggestions before i tear this appart tomorrow?

lol
Thanks for your patience...
Michael

There is absolutely NO fan nothing on 1,2,3,4 or 5... there is radiant heat of course but NO FAN at all. i checked the fuses under the hood and in the glove box they are all good... i also tried the new Control unit and nothing on all 5 fan settings.

any more suggestions before i tear this appart tomorrow?

lol
Thanks for your patience...
Michael

I'm glad we recapped your problem so you don't waste any money or replace something that may not fix your problem. When a BMR goes bad you normally lose positions 1 -4. Position 5 normally works because the BMR is bypassed and direct 12v is applied to the blower via a HVAC hi speed relay. Having said this, it indicates that your blower motor is bad or the squirrel cage is obstructed.

But I have seen situations where both the blower and resistor are bad because the BMR takes out the motor. So it's 50/50. However, the resistor is cheaper than the blower. Good luck and let us know how it turns out.

I'm glad we recapped your problem so you don't waste any money or replace something that may not fix your problem. When a BMR goes bad you normally lose positions 1 -4. Position 5 normally works because the BMR is bypassed and direct 12v is applied to the blower via a HVAC hi speed relay. Having said this, it indicates that your blower motor is bad or the squirrel cage is obstructed.

But I have seen situations where both the blower and resistor are bad because the BMR takes out the motor. So it's 50/50. However, the resistor is cheaper than the blower. Good luck and let us know how it turns out.

if i remove the blower motor and apply 12v is that a safe test to rule it out?

if i remove the blower motor and apply 12v is that a safe test to rule it out?

Yes, you can apply 12v to see if it turns but I'd do that with the blower motor out. It will also give you the opportunity to move the squirrel cage by hand to see if it is bound up.

Yes, you can apply 12v to see if it turns but I'd do that with the blower motor out. It will also give you the opportunity to move the squirrel cage by hand to see if it is bound up.

well it seems that the only place that has the resister is online for 18.99, takes about a week to get unless i want to get :banghead: by the dealer and pay 44.99. the blower motor and cage is 89.99. here is my question assuming that the both items are bad and i get the new motor can i bypass the resistor to have the fan run full time until the new resistor gets here.

Michael

well it seems that the only place that has the resister is online for 18.99, takes about a week to get unless i want to get :banghead: by the dealer and pay 44.99. the blower motor and cage is 89.99. here is my question assuming that the both items are bad and i get the new motor can i bypass the resistor to have the fan run full time until the new resistor gets here.

Michael

Test your blower first. If it doesn't turn, then it is the problem and you may not have to worry about a blower motor resistor.

If both the motor and resistor are bad I wouldn't take any chance by bypassing the BMR. Some of the resistors are in bad shape (fried) and make take out your new blower motor. :dunno:

Test your blower first. If it doesn't turn, then it is the problem and you may not have to worry about a blower motor resistor.

If both the motor and resistor are bad I wouldn't take any chance by bypassing the BMR. Some of the resistors are in bad shape (fried) and make take out your new blower motor. :dunno:

Hey im ecstatic! It was the Blower Motor Resistor! I cannot thank you enough for your help in diagnosing this issue. I tested the fan she worked, so I made it up to the dealer 5 min before closing and got the resister from them, unfortunately its ACDELCO which means ill prolly order the aftermarket one made by WELLS and keep it on hand, it was only 18 bucks. I paid 44 at the dealer. anyway I have attached 2 pictures of the bad resistor, for reference, I think who ever designed this system didn’t take in account for the condensation created by the A/C because you can see the rust on the resistor and the fan blower housing... oh well.. It works! I wish I could buy you a round of drinks for your help!!!!


Thanks sooo much!

Michael

http://i13.photobucket.com/albums/a300/weaselphd/ForumPosts/DSC03475.jpg

http://i13.photobucket.com/albums/a300/weaselphd/ForumPosts/DSC03474.jpg

Hey im ecstatic! It was the Blower Motor Resistor! I cannot thank you enough for your help in diagnosing this issue. I tested the fan she worked, so I made it up to the dealer 5 min before closing and got the resister from them, unfortunately its ACDELCO which means ill prolly order the aftermarket one made by WELLS and keep it on hand, it was only 18 bucks. I paid 44 at the dealer. anyway I have attached 2 pictures of the bad resistor, for reference, I think who ever designed this system didn’t take in account for the condensation created by the A/C because you can see the rust on the resistor and the fan blower housing... oh well.. It works! I wish I could buy you a round of drinks for your help!!!!


Thanks sooo much!

Michael


So here we are not even a year later and POS AC delco junk dies again! again the Blower Motor resistor dies, after being screwed at the dealer 44 bucks for this junk. ordered a replacement from Autozone 18.99 made by WELLS, i swear i cannot wait to get rid of this lemmon of a car! anyway now that im done crying :crying: i wanted to post this incase someone else needs one DO NOT BUY DEALER OEM JUNK PARTS! go to autozone.com part number DR783 made by WELLS. they didnt carry it in the store unfortunately.

good luck!
:2cents:
Michael

I was wondering i am currently replacing this stupid blower motor resistor for the 5th time this year, i replace it and it runs good for a couple months then it starts to lose, sections 1 then 2 then 3,4,5 till it no longer functions, i have replaced it and the cycle starts again. here is my question this is a pain to keep replacing every couple months, WHAT could possibly be causing this resistor to burn out? could the blower motor itself have a short or something that is electrically frying this resistor, or would this issue take place prior to the resistor? and is there an easy way to track down this problem?

thanks
Michael




Hey im ecstatic! It was the Blower Motor Resistor! I cannot thank you enough for your help in diagnosing this issue. I tested the fan she worked, so I made it up to the dealer 5 min before closing and got the resister from them, unfortunately its ACDELCO which means ill prolly order the aftermarket one made by WELLS and keep it on hand, it was only 18 bucks. I paid 44 at the dealer. anyway I have attached 2 pictures of the bad resistor, for reference, I think who ever designed this system didn’t take in account for the condensation created by the A/C because you can see the rust on the resistor and the fan blower housing... oh well.. It works! I wish I could buy you a round of drinks for your help!!!!


Thanks sooo much!

Michael

http://i13.photobucket.com/albums/a300/weaselphd/ForumPosts/DSC03475.jpg

http://i13.photobucket.com/albums/a300/weaselphd/ForumPosts/DSC03474.jpg

I was wondering i am currently replacing this stupid blower motor resistor for the 5th time this year, i replace it and it runs good for a couple months then it starts to lose, sections 1 then 2 then 3,4,5 till it no longer functions, i have replaced it and the cycle starts again. here is my question this is a pain to keep replacing every couple months, WHAT could possibly be causing this resistor to burn out? could the blower motor itself have a short or something that is electrically frying this resistor, or would this issue take place prior to the resistor? and is there an easy way to track down this problem?

thanks
Michael

I hate to be the bringer of bad new but it sounds like your ignition switch needs replacement. This is one of the classic symptoms especially since you are going through so many blower motor resistors.

What happens is the contacts carbon up and act like a big resistor causing the current in the overall circuit to go up. Also, the contacts arc out which causes electrical component damage.

The ignition switch and harness runs around $100-$125 at the dealer. Actually it is easy to replace DIY and save money on labor costs. Checkout our new Tips and Maintenance subforum which has a R&R procedure to replace it. Good luck.

http://www.automotiveforums.com/vbulletin/forumdisplay.php?f=2142

Ok when you say ignition switch is that the key and harness? thats an odd one.. do they sell these aftermarket?

thanks
Michael


I hate to be the bringer of bad new but it sounds like your ignition switch needs replacement. This is one of the classic symptoms especially since you are going through so many blower motor resistors.

What happens is the contacts carbon up and act like a big resistor causing the current in the overall circuit to go up. Also, the contacts arc out which causes electrical component damage.

The ignition switch and harness runs around $100-$125 at the dealer. Actually it is easy to replace DIY and save money on labor costs. Checkout our new Tips and Maintenance subforum which has a R&R procedure to replace it. Good luck.

http://www.automotiveforums.com/vbulletin/forumdisplay.php?f=2142

Ok when you say ignition switch is that the key and harness? thats an odd one.. do they sell these aftermarket?

thanks
Michael

It is called an ignition switch and harness assembly. The contacts are located in the square black module. See pic below. The ignition key cylinder is a separate part and probably does not need to be replaced. These parts are GM dealer only or AC Delco Authorized Parts Stores.

http://i5.photobucket.com/albums/y186/lizzywiz/switch_igntion.gif

If it is carbon buildup, cant the harness be removed and cleaned and reinstalled?

It is called an ignition switch and harness assembly. The contacts are located in the square black module. See pic below. The ignition key cylinder is a separate part and probably does not need to be replaced. These parts are GM dealer only or AC Delco Authorized Parts Stores.

http://i5.photobucket.com/albums/y186/lizzywiz/switch_igntion.gif

If it is carbon buildup, cant the harness be removed and cleaned and reinstalled?

If you are very careful, yes. Alot of people were able to salvage and re-use the ignition switch. The module can be disassembled where you can inspect and clean the electrical contacts. Inside there are cams and springs along with the contacts that have to be placed just right or the switch won't work properly. Worth a try and nothing to lose but all to gain. Good luck.

Could the resistor problems be caused by water intrusion due to a bad cowl seal? When you dropped the motor out, did you have a puddle of water in the heater box or are all the defective resistors rusted? Installing a cabin air filter from a similar year Regal helps with the water intrusion issue, if this proves to be the case. I didn't read all the posts from the beginning, so if I'm rehashing old topics here, I apologize.

Ok thats sounds like a lot of work and my luck it wont work, so i ordered the harness, and the new resistor, they are of course "on order" and as luck would have it, it is freezing rain, snow and 20 degrees here, sooo.. i need to ask one question for a temporary fix.... if i cut the red & black wire off the resistor and wire on a cig. lighter plug so that the fan will operate at full speed until the parts come do your forsee any issues here? the red and black are Posative and Ground right?

thanks
Michael

If you are very careful, yes. Alot of people were able to salvage and re-use the ignition switch. The module can be disassembled where you can inspect and clean the electrical contacts. Inside there are cams and springs along with the contacts that have to be placed just right or the switch won't work properly. Worth a try and nothing to lose but all to gain. Good luck.

No there were no signs of water i think the rust on the original one i replaced was from condensation fro mthe A/C. but great point i will still replace that item as well.

Thanks
Michael

Could the resistor problems be caused by water intrusion due to a bad cowl seal? When you dropped the motor out, did you have a puddle of water in the heater box or are all the defective resistors rusted? Installing a cabin air filter from a similar year Regal helps with the water intrusion issue, if this proves to be the case. I didn't read all the posts from the beginning, so if I'm rehashing old topics here, I apologize.