A/C funny business

[Pokémon]

Haven't posted for a while but since I bought my Tahoe a little over a year ago the A/C hasn't worked properly and rear A/C won't adjust heat or wether it blows in your face or feet. The fan motor works fine though.
When the outside temperature has been above 68 degrees the A/C almost always comes on if I have preset the HVAC control to it's coldest setting, which is great but I also need it to start when is cold and raining so I can get the fog of the windows.

So what has been done so far:
Front
Replace A/C pump
Both sensor
acumulator
Front HVAC control panel

Rear
actuators
Rear HVAC control panel
Control module

I can jump the A/C on through the fuse box. But thats the only way when the temp is below 68

So...to date I've spent close to $2000 on parts, labour and diagnostic but no workshop seems to know what is going on. In talks with other workshop who say they can fix it but won't give me what they think it might be. Their hourly rate for diagnostics is more than I have at the moment.

So now I'm at the point of either giving up and selling my 'hoe and buying some japanese s**tbox or accepting the fate of no A/C (which I really don't want)

I'm sincerly hoping that there is someone here that might help me.

Regards,
Desperate Tahoe owner.

 

[about20ninj45]

This may help

You've replaced everything except the major culprit, which is your bcm ( body control module ) go pull one from the junk yard and see if that fixes your issue. If you have any other electrical issues in the vehicle, this may also help fix it

Haven't posted for a while but since I bought my Tahoe a little over a year ago the A/C hasn't worked properly and rear A/C won't adjust heat or wether it blows in your face or feet. The fan motor works fine though.
When the outside temperature has been above 68 degrees the A/C almost always comes on if I have preset the HVAC control to it's coldest setting, which is great but I also need it to start when is cold and raining so I can get the fog of the windows.

So what has been done so far:
Front
Replace A/C pump
Both sensor
acumulator
Front HVAC control panel

Rear
actuators
Rear HVAC control panel
Control module

I can jump the A/C on through the fuse box. But thats the only way when the temp is below 68

So...to date I've spent close to $2000 on parts, labour and diagnostic but no workshop seems to know what is going on. In talks with other workshop who say they can fix it but won't give me what they think it might be. Their hourly rate for diagnostics is more than I have at the moment.

So now I'm at the point of either giving up and selling my 'hoe and buying some japanese s**tbox or accepting the fate of no A/C (which I really don't want)

I'm sincerly hoping that there is someone here that might help me.

Regards,
Desperate Tahoe owner.

 

[Pokémon]

You've replaced everything except the major culprit, which is your bcm ( body control module ) go pull one from the junk yard and see if that fixes your issue. If you have any other electrical issues in the vehicle, this may also help fix it

Thanks for the quick response. Living in Iceland there are only a handfull of GM trucks here and almost none at the yard. Any advice on where I could buy it for the least amount of $$?

 

[SLCHOE]

Haven't posted for a while but since I bought my Tahoe a little over a year ago the A/C hasn't worked properly and rear A/C won't adjust heat or wether it blows in your face or feet. The fan motor works fine though.
When the outside temperature has been above 68 degrees the A/C almost always comes on if I have preset the HVAC control to it's coldest setting, which is great but I also need it to start when is cold and raining so I can get the fog of the windows.

So what has been done so far:
Front
Replace A/C pump
Both sensor
acumulator
Front HVAC control panel

Rear
actuators
Rear HVAC control panel
Control module

I can jump the A/C on through the fuse box. But thats the only way when the temp is below 68

So...to date I've spent close to $2000 on parts, labour and diagnostic but no workshop seems to know what is going on. In talks with other workshop who say they can fix it but won't give me what they think it might be. Their hourly rate for diagnostics is more than I have at the moment.

So now I'm at the point of either giving up and selling my 'hoe and buying some japanese s**tbox or accepting the fate of no A/C (which I really don't want)

I'm sincerly hoping that there is someone here that might help me.

Regards,
Desperate Tahoe owner.

Did they pull any codes from the HVAC Control Module? It's a Class-2 device (CANBUS) so you can communicate with it via scantool and read codes and watch live data.

 

[Pokémon]

Did they pull any codes from the HVAC Control Module? It's a Class-2 device (CANBUS) so you can communicate with it via scantool and read codes and watch live data.

Not that I know, last scantool gave no codes according to mech.

---------- Post added at 10:34 PM ---------- Previous post was at 10:31 PM ----------

http://www.rockauto.com/catalog/raframecatalog.php?carcode=1412244&parttype=2888&ck[ID]=0&ck[idlist]=0&ck[viewcurrency]=USD&ck[PHP_SESSION_ID]=gshk6ftfunvsjiosg2smfi8n43

does the bcm module require any programming after installation or is it plug and play?

 

[about20ninj45]

Plug and play

Not that I know, last scantool gave no codes according to mech.

---------- Post added at 10:34 PM ---------- Previous post was at 10:31 PM ----------

http://www.rockauto.com/catalog/raframecatalog.php?carcode=1412244&parttype=2888&ck[ID]=0&ck[idlist]=0&ck[viewcurrency]=USD&ck[PHP_SESSION_ID]=gshk6ftfunvsjiosg2smfi8n43

does the bcm module require any programming after installation or is it plug and play?

---------- Post added at 07:06 PM ---------- Previous post was at 07:05 PM ----------

Plug and play if you get it off another vehicle

Not that I know, last scantool gave no codes according to mech.

---------- Post added at 10:34 PM ---------- Previous post was at 10:31 PM ----------

http://www.rockauto.com/catalog/raframecatalog.php?carcode=1412244&parttype=2888&ck[ID]=0&ck[idlist]=0&ck[viewcurrency]=USD&ck[PHP_SESSION_ID]=gshk6ftfunvsjiosg2smfi8n43

does the bcm module require any programming after installation or is it plug and play?

 

[Pokémon]

Plug and play



---------- Post added at 07:06 PM ---------- Previous post was at 07:05 PM ----------

Plug and play if you get it off another vehicle

Thanks

 

[#1taho]

Thanks

If not a BCM. I would look for a broken wire. You replaced everything else

 

[Pokémon]

If not a BCM. I would look for a broken wire. You replaced everything else

I get chills down the spine thinking about that. Hopefully it's the bcm. I've had some electrical issues regarding the seat heater and seat position controls ( they work in reverse compared to passenger seat.) Driver 1 seat recall and easy exit works fine but driver 2 easy exit settings puts the seat full forward. My wife was very happy with that haha

 

[#1taho]

I think you found your problem

 

[Pokémon]

I think you found your problem

BCM or wire?

 

[#1taho]

BCM
Almost everything inside is controlled by it. with as many problems as you are having it's a good place to start. Please let us know how you make out.

 

[Pokémon]

BCM
Almost everything inside is controlled by it. with as many problems as you are having it's a good place to start. Please let us know how you make out.

Thanks, will do.

 

[Pokémon]

Ok time for an update.

Bought a used BCM, had a local shop install it and wait for it.....

....absolutely no change.

Got to the point were I considered selling it. Found an 08 Escalade for a fair price, love the engine and transmission but it had almost the same problem as my car. A/C and seat heaters didn't work.
Guess I'm just not meant to be cool.

Back to the drawing board.

 

[Pokémon]

I'm not willing to give up on this. Now I'm thinking the problems might not be connected. So if I look at them as individual problems.

Front HVAC.
1.AC doesn't turn on if outside temp is lower than 68F
2. Will not cool or blow cold unless I set HVAC to coldest setting. If set on auto theres Lot of difference between the lowest setting and a degree above lowest. Fan motor won't increase speed until it is set to the lowest temp and blow relatively cold air .
3. To maintain a comfortable temp and not having it blowing hot air all the time I need to set it at 60-63 degrees.

Scan tool reveals no DTC or problems.

Solutions:
1. Maybe interior ambient sensor is faulty or off calibration. Outside ambient temp seems to be working fine. At least the temp shown in the mirror are about right.
2. Wiring is shot or worn.

Rear HVAC.
Won't change modes or temp setting. Fan motor works fine.

Solutions
1. After changing the control module and actuator I think that only leaves a problem with wiring or the whole assembly needs replacing like one of the shops suggested.

Thats all for today.

 

[Pokémon]

Now things have changed quite a bit. I borrowed a Tech2 and I've found that AC permission was witheld. Hopefully granting it permission again will get rid of that problem for good.
The only DTC I had was in something marked RCC. Which I believe is the rear climate control module.
Maybe the new module doesn't work properly because it wasn't installed with tech2 in hand. Still have the old module I'll try using that again.

 

[C3MP69]

Any update on this. I have the same rear HVAC issue.

 

[rockola1971]

If you have automatic climate control it sounds like you need a new one. The temp sensor could be junk as well.

Rear HVAC module may need just reset. Pull positive lead for 10 mins, touch the positive lead to negative lead for a few seconds, reattach positive lead to battery. Start vehicle but make sure all controls are set to off first. Set AC on auto (if equipped), turn rear air on and the module will recal all blend motors and vent motors. There are some modules that have been updated with a new part #. Module is underneath trim at passenger side rear cargo area window. Forward of evaporator.

*Note* rear AC module is controlled by BCM.