Panth3r427

Hello, i have a 2005 Silverado 1500, Z71, 4x4.
when i turn the key/start the truck....the heater is stuck on low and i can't adjust it until the truck warms up.
reservoir is fine, the 2 hoses to the heater core are warm/hot...
dont see any leaks anywhere...
any help would be great, thanks

mountainmanjoe

low fan speed or low temperature?

Panth3r427

yes, both.... it automatically starts out on low temp/low speed, and its cool air because the truck isn't warmed up yet.

tech2

auto hvac or manual? if its an auto system...make sure the auto is off. auto mode is designed to run slow until it warms up and can pump out heat

Panth3r427

It's auto but none of the buttons work, i cant turn it off, change the temp, adjust the fan speed, nothing !

Gumby22

The HVAC control panel receives battery voltage from the HVAC/ECAS fuse in the under hood fuse block as well as the HVAC fuse in the instrument panel fuse block at the left end of the dash. Check that both fuses are good and verify the HVAC fuse in the instrument panel has power with the key on.

If the fuses are good, the next step is to remove the control panel and check for power/ground at the HVAC panel connectors.

Panth3r427

Both the fuses are good. (under the hood, left side of dash). question: if one of those fuses were bad, then the controls wouldn't even power up right ?
So, would it be safe to say that the temperature control actuator is faulty?
Another question: can the HVAC system be scanned with a code reader? If so, what type?

Gumby22

1) Yes that’s how it should work, but if the ignition feed were shorted to another voltage supply circuit, it’s possible the panel would still power on even if the HVAC fuse in the cabin was blown. However, in that case it’s likely you’d see other problems.

2) No, it wouldn’t be safe to say that. A problem with the control panel could present problems with other parts of the system, including the temperature blend and blower controls. Depending on the nature of the control failure, it’s possible the system defaulted to auto until the fault is corrected, whether that means replacing the control panel or repairing wiring.

3) Yes. It requires a scanner capable of reading body codes. You might be able to find an OBD2 dongle and smart phone app to read them; or you could call a few shops to see what they’d charge to read them for you.