how do i fix a 2003 gmc sonoma problem with the heater that does not heat. I changed the thermostat, but all I get is cold air blowing.
2003 GMC Sonoma ZR5 4.3 L V6
Replaced thermostat, checked fluid levels,verified fan blower is working,
If you let the engine get up to operating temp are you able to verify that both heater core connections at the firewall are getting hot?
yes firewall heater hoses are hot
compressor is cycling
Ok the first thing I would recommend would be to verify that the fuse labeled HVAC 1. The next item I would be interested in would be the actual electric actuator that moves the door in the hvac box. The problem is that most of the dash needs to be removed to access this point. The actuator itself is located on the passenger upper side of the havc box. This electric actuator is a common failure in this model. We would need to access the actuator to see if the actuator is moving, and also to verify that the heater door is not broken. Here is an overview of what you will need to do to access this actuator. Feel free to contact me with any questions! Good luck!
Important: Always disconnect the brown electrical connector from the body control module (BCM) before disconnecting the purple electrical connector from the BCM.
Important: Label all of the connections in order to avoid improper installation.