03 C5 with an LS-1 and a six speed has a heat problem. When running the heater, air output seems adequate from the A/C vents if those are selected. If the floor vents are selected, the air flow is greatly diminished. How do I fix this?

 

Search the forum for how to index the HVAC blend door actuators

 

Thanks! Tried everything short of removing the actuators for repair/replacement and still have the same problem with low air volume from the floor heater vents when they are selected. Also, the car has the much loved dual climate zone system. Anyone out there got any simple solutions that worked for this problem?

 

I replaced my actuators. Believe me, if I can do this, you can do this.
It seems impossible but it actually was a step by step process. And I enjoyed the satisfaction and surprise from my wife.

 

Moved to C5 Tech.

 

All the air FLOW CONTROL is vacuum controlled!! If you cant change the flow control (top vents, Bi Level, Lower Vents Defrost ect) You have a vacuum or Vacuum solenoid motor issue. The vacuum comes from the back of the intake manifold, goes to a vacuum canister and distributed from there. It runs thru small NYLON vacuum line under the hood and rubber one in the dash.

The HVAC Temperature Actuators are electric and ONLY control the air temperature of the outlets.

Bill

 

It's fixed ! Following Bill's advice, I checked all the vacuum lines and found no problems. Looking for access to the passenger actuator, I took out the kick panels and under dash covers on the passenger side and noted nothing remarkable. Remembered one writer in the HVAC string saying he removed and replaced mini fuse number 27 on the under the glove box breaker box and fixed an airflow issue on his machine temporarily...having nothing to lose I pulled and replaced that fuse with the engine running and floor heat selected. The HVAC fan shut off when the fuse was pulled but I was greeted with copious warm airflow from both floor vents when I plugged the fuse back in. Ran through several starts just to be sure I wasn't hallucinating and the fix held ......I have no idea why that worked, but as an aside, on the last start, the TPMS went out to lunch and demanded reteaching but refused to learn...I have been down that road before, that's low voltage. Put a six amp charger on for a few minutes and the TPMS then accepted teaching. I can see a new Delco in the near future....
I would bet the battery may have had something to do with the HVAC issue as well. These cars get plumb weird with low voltage! Thanks to all that replied, would have hated to pay a stealership to figure all that out!

Cheers!

 

Went to replace the battery today and was greeted by a warning light for low brake fluid and a mooshy pedal. Topped off the master cylinder and it managed to empty itself again in about 2 minutes of running.........had this happen once in a 68 Chevy wagon....caused by a hole in the power brake booster diaphragm. Fluid sucks right past the diaphragm through the hole and in to the vacuum hose hooked to the intake manifold and gets burned in the engine. Made an appointment to get a new booster..diaphragms with holes in them are certainly a source of great sadness in any situation.....

Cheers