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2003 GM HVAC Codes?

dhcomp

dhcomp

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Team,

The HVAC in the 2003 Burb is all screwed up. From the research I've done, there are all sorts of actuators that can go bad, and the HVAC codes need to be read.

What type of a code reader do I need to read gm 2003+ bus type communication codes?

Please help.

On max heat, it gets kinda warm after 20 min. Freezing my balls off during my first real winter in the mtns. Luckily I'm not driving this thing often. Thanks!
 
I think you're probably going to need a tech 2 or MDI to get the most of reading those kind of codes. EFIlive is able to read a bunch of them, however.
 
dhcomp said:
Team,

The HVAC in the 2003 Burb is all screwed up. From the research I've done, there are all sorts of actuators that can go bad, and the HVAC codes need to be read.

What type of a code reader do I need to read gm 2003+ bus type communication codes?

Please help.

On max heat, it gets kinda warm after 20 min. Freezing my balls off during my first real winter in the mtns. Luckily I'm not driving this thing often. Thanks!
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Driver and passenger side both cold? Rear heat cold? Actuators are common on these and can be diagnosed with symptoms and is not necessary to read codes. Not unusual for a thermostat to stick open on a D-max and cause heater issues as well.
 
I know nothing about this dmax. Are they manual tstats, or are they automatic?

It warms up pretty slow, could easily be stuck open.

I get no heat at all unless its set to 90 degrees. Maybe that is some sort of override? And then i don't get much. Low, dash, and defrost blend doesn't work at all.

I've gone through the recal, it doesn't seem to help.

Probably actuators.
 
Russell said:
Does your engine blow coolant out? Does it make heat when you are over 2000 rpm?
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Blow coolant? Out of where?

I live a mile or 2 from the freeway. Once i get on the freeway, i don't get heat for 10-15 miles. So, not too sure on specific RPM's.

Seems like 2 standard tstats, are they eazy enough to replace on the LBZ?

At this point, for $35, I'll probably replace them for the piece of mind.

It sounds like the temp blend door, and the location blend door actuators can both be replaced. Any way to know if i need them and not some resistor or new controller?

Just replacing those actuators along is a couple hundred dollars. Looking to stray from my normal ways and actually diagnose this instead of just throwing parts at it.

Thanks guys!
 
I've got the auto dual zone controller. Is it stupid or difficult to want to change to the manual one? I run it in manual all the time anyways.
 
Does the rear heat work? We need to narrow down if it is a heater box problem or a coolant temperature problem. There are 3 separate temperature blend actuators. One for the driver's side, one for the passenger side and one for the rear heater. Very unlikely all three are bad. AGAIN the actuators fail often but that does not mean they are bad. They aren't that much fun to replace so take a little time to diagnose the issue beforehand.

There is no advantage of ditching the auto temp control, the manual system still uses electric actuators.

Any generic scan tool can tell you what the coolant temperature is, the coolant should stay 190ish degrees when going down the highway for at least 10 miles. If it is much below that then the thermostats need to be replaced. Don't rely on the gauge in the dash when testing thermostats.

Don't put aftermarket t-stats in that, you'll regret it. Get them from the dealer and they are different not two of the same. Yes they are expensive, it's a diesel get used to everything being expensive. They aren't real easy to do probably take you 2-3 hours to replace them. Make sure you take the time to diagnose the problem, this is not time or money you want to waste.
 
My dmax takes 15min to heat up. Exactly why I put high idle in and block off half the radiator in the winter.
 
dhcomp said:
Blow coolant? Out of where?

I live a mile or 2 from the freeway. Once i get on the freeway, i don't get heat for 10-15 miles. So, not too sure on specific RPM's.
Click to expand...

Out of the coolant bottle overflow. It is common for LB7 engines to blow headgaskets. You don't always notice in how it runs, but it'll pressurize the cooling system with exhaust gasses causing coolant to blow out and it'll also cause coolant circulation problems which means that your heater core will go cold unless you've spun the engine fast to get it moving again.
 
Russell said:
Out of the coolant bottle overflow. It is common for LB7 engines to blow headgaskets. You don't always notice in how it runs, but it'll pressurize the cooling system with exhaust gasses causing coolant to blow out and it'll also cause coolant circulation problems which means that your heater core will go cold unless you've spun the engine fast to get it moving again.
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usually the blackened coolant bottle is the dead give away.
 
I'll check it, but i think its fine. Just need to get the hvac controls and actuators figured out.

Thanks guys.
 
No evidence of a head gasket. Truck warms up fine. Runs at 185 as it is supposed to.

Cold starts a lot better when I plug it into a working outlet:deal:

So any tips for troubleshooting the actuators, or so I just replace them all?

Thanks!
 
Funny this thread pops up, my 2002 tahoe as of yesterday is having issues with the blend doors and I can hear a weird clicking/tap noise behind the dash. I don't even want to think about all the crap I need to remove to gain access to these actuators.
 
skunked said:
Funny this thread pops up, my 2002 tahoe as of yesterday is having issues with the blend doors and I can hear a weird clicking/tap noise behind the dash. I don't even want to think about all the crap I need to remove to gain access to these actuators.
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Mine has been clicking too so finally went for the change. There are, I think, 3 actuators. One on bottom of box and pretty easy to change. The second, I don't know, but the third one was my clicking one and the most difficult to change. It's buried on top of the box but below some duct work and metal bracing.

You need to dedicate probably 3 hrs to change it, and it involves removing the passenger air bag. Lots of pieces to the disassembly but there is a good thread on it.

Be sure to get a genuine AC Delco one....you don't want to do it twice!

Here is the thread with writeup link (and a lot of pictures to help!)
https://ck5.com/forums/threads/2004-yukon-xl-passenger-side-blending-door-actuator.323344/
 
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Thanks for the info Jeff, that's very helpful. In my situation I believe the bad actuator is the one that changes the output of the air as it's stuck on defrost. I'll take a look at that thread because I'll probably change all of them while it's tore down.
 
dhcomp said:
No evidence of a head gasket. Truck warms up fine. Runs at 185 as it is supposed to.

Cold starts a lot better when I plug it into a working outlet:deal:

So any tips for troubleshooting the actuators, or so I just replace them all?

Thanks!
Click to expand...

Does the rear heater get warm? Does the passenger side get warm?
 
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