I have a 11’ VW Routan and just started having the following issue:
Minimal amount of heat, even after the temp gauge indicates that the engine is up to operating temperature. On cold days the car warms up fine and sometimes I get very hot air heat (normal) coming from the vents then all of sudden the air goes cold or lukewarm. I need to stop the van, turn off the ignition and restart the van for the heat to come back. But every once in a while; while the cold air is coming out, it does hot again.
Any ideas as to what the problem(s?) might be?
More than likely the problem is the mix door motor is sticking or bad.
You have a sticking thermostat and possibly air in the system.
You need to have the system pressure checked and the T-stat changed (which will also include purging the system of air, as one should always do when changing the T-stat.
Fortunately, these are very affordable. And if a leak is found in the system, it’ll be cheaper to get it fixed now that after the engine overheats.
Chrysler has issued a service bulletin to correct this problem (this vehicle was manufactured by Chrysler for VW).
Customers may experience the following condition:
HVAC system intermittently blows cold regardless of blend door/temperature setting.
Updating the HVAC software will correct this condition.
From what you’re describing, the problem might be with the HVAC control module.
The HVAC control module is basically a small computer that controls various doors in the vent system to provide where the air comes out of the vent system, how warm/cold the air is, and also controls the fan speed.
It’s possible to connect a scan tool to the vehicle to determine if the HVAC control module is in proper calibration and if the HVAC control module is operating correctly.
If the problem is found to be with the HVAC control module, it cannot be repaired, it must be replaced.