Tech Question re my Chevrolet Avalanche

[ErVikingo]

vehicle: 2003 Chevrolet Avalanche 1500 Z-66 On Road Edition. All options


New mystery. HVAC blows warm, refrigerant is OK, pressure switch is new.

Now, HVAC control display wont light up?????

Switches work but not the LED display. Removed and cleaned all fuses, disconnected battery for 30 minutes and tried again (no luck).

Took out switch/control/display (word to the wise the plastic snap clips get brittle and break) cleaned contacts. When you plug in the display shows 75 degrees for 1 sec or less and shuts off.

Ideas????? I have searched and not found solutions. THANKS!

[asphaltgambler]

Well, you be sure if the control head is not online with the canbus - nuttin's gonna happen. Need you a decent scan tool, see what's up.

[Steve Carlton]

Originally Posted by asphaltgambler

Need you a decent scan tool, see what's up.

[nota]

does the compressor pulley switch/relay get power

if not that try a pick and pull parts swap of the control head/screen

[ErVikingo]

Thanks. My scanner does a lot (including airbag system) but not electrical/hvac

Compressor cycles (I change the pressure switch) and checked pressures. Air blows warm and I wonder if it’s the blend “valves” being out of whack and mixing in hot air to get to the perceived temp on the controls.

Oddly enough, it stopped cooling and as I was checking pressures the display “died”.

When I plug the display, it lights up (at the default 75 degrees) for less than 0.5 secs. It goes dark then.

Switches work (turns on/off blower, changes blower speeds).

Guess I need to replace the control. Hate to just throw $ in hopes it fixes it.

Thanks all for the feedback. I need Yoda’s knowledge!

[cabmandone]

Can you access the blend door actuators to make sure they're moving by unplugging and plugging back in? I suppose you could remove the actuator and move the blend door by hand??

[ErVikingo]

Originally Posted by cabmando

Can you access the blend door actuators to make sure they're moving by unplugging and plugging back in? I suppose you could remove the actuator and move the blend door by hand??

Couldn't see them without taking too many things apart. That is next, read that to get to the one on the right side, I have to remove the airbag.

The saga continues....

[stomachmonkey]

Originally Posted by ErVikingo

Couldn't see them without taking too many things apart. That is next, read that to get to the one on the right side, I have to remove the airbag.

The saga continues....

You should be able to hear the blend doors in operation. No need to tear it apart.

Had the same issue with my 01" Tahoe. It would blow cool for a couple of minutes then just give up the ghost.

Never figured it out and sold it that way. Was basically a ranch truck by that time anyway, moved maybe 100 miles a year so was not too invested in fixing it.

[ErVikingo]

Originally Posted by stomachmonkey

You should be able to hear the blend doors in operation. No need to tear it apart.

Had the same issue with my 01" Tahoe. It would blow cool for a couple of minutes then just give up the ghost.

Never figured it out and sold it that way. Was basically a ranch truck by that time anyway, moved maybe 100 miles a year so was not too invested in fixing it.

Yup should be, going to get under the dash and hear for the doors. I've had this one since 2002 and its used as the landscape/project truck and to transport bikes to/from the trails.

Almost getting to the point of fixing to trade it in on a new small truck or SUV. (house is built, kids are almost out of school)

[A930Rocket]

Originally Posted by cabmando

Can you access the blend door actuators to make sure they're moving by unplugging and plugging back in? I suppose you could remove the actuator and move the blend door by hand??

If I recall correctly, that was the issue with our 05 Tahoe. It worked great and then all of a sudden it would blow hot air. Nothing could stop it. Then one day it would start blowing cold air. Since little Rocket was driving it, he wasn’t worried about it.