03 Trailblazer still over heating after replacement of Radiator, water pump, clutch fan, and thermostat. It only over heats with the AC
Last edited by KingReese (7/29/2016 3:54 PM)
It's possible that the engine is air bound and needs to be bled out.
With the front of the truck on ramps or jack stands; remove the radiator cap and start the engine. Watch the coolant level constantly as the engine warms up and the thermostat opens up. As the coolant level goes down keep filling the radiator until it does not require anymore. This process could last about 30 to 60 minutes. Replace the cap and fill the reservoir and test drive.
There is also a service bulletin on a condition that is similar to what you are asking about. It could be a help if there is no fix for your vehicle. I listed it below.
Bulletin No.: 04-06-02-005
Date: July 27, 2004
Higher Than Normal Engine Coolant Temperature Gauge Readings (Reprogram PCM)
2004 Buick Rainier
2002-2004 Chevrolet TrailBlazer, TrailBlazer EXT
2002-2004 GMC Envoy, Envoy XL
2004 GMC Envoy XUV
2002-2004 Oldsmobile Bravada
Condition: Some customers may comment on higher than normal engine coolant temperature gauge readings when operating the vehicle in very high outside ambient temperatures, and in stop and go or slow moving traffic.
Cause: Reduced air flow across the radiator and preheated air from stopped or slow moving driving conditions from traffic congestion may result in normally higher engine coolant operating temperatures as indicated by the temperature gauge.
Correction: Technicians are to reprogram the PCM with an updated software calibration. This new service calibration was released with TIS satellite data update version 7.3 available July 7, 2004.
This new calibration will cause the PCM to command small amounts of additional fan engagement to control engine coolant temperatures and gauge readings closer to a customer perception of normal.
Let me know how you make out.
Service Bulletin is supplied by the Alldata automotive information website.