How do fix a/c on 2003 yukon it blow cold then hot than back to cold
A few possibilities:
Stuck or inoperable Air-flow Diverter:
There are tow types of air-flow diverters: Vacuum Actuated and Slide-Cable Actuated (some will have an electric solenoid that controls a vacuum actuated type). In either case the default position of the diverter is "cold air" or closed - blocking air flow over the heater core. Sounds like it may have a vacuum actuated control - when it looses vacuum it will let the air-flow diverter swing shut blocking off air blow through the heater core resulting in "cold air" Could be a bad control/slider, bad or loose hose, or bad actuator. If you remove the blower motor assembly you will be able to see the diverter and might be able to tell the issue is.
Stuck or inoperable heater valve:
This valve controls the flow of engine coolant to/through the heater core. It is normally closed - blocking flow. This can be vacuum operated or cable controlled just like the air-flow diverter. Simple to check - in the engine compartment, to the left of the engine locate the cooling (heating) lines that go into the fire wall - locate the valve and check its operation.
Another possibility is low coolant level in your engine/radiator which may be too low to allow flow of the coolant through the heating coil, although you would likely notice that the engine was over heating/running hot.
Sep 13, 2014 |
Flex A Lite 2003 GMC Yukon XL - 6.0L V8 -...