brewtoo,

Thanks for the response. In the past I have never pressed the Recirc button either. Yes, that was my thinking before perusing some of the MB service info. Somewhere in that reading I got the idea that the climate control unit will put the system in recirc mode if the cabin temp is high enough.

I hope my problem does NOT lie in the recirc pod. The thought of taking off the dash does not excite me. I should know tonight. I will pull the glovebox and check vacuum. If all vac is well, I am going to try to read the code pulses from the diag connector with an analog voltmeter. If that doesn't work, I'll rig up an LED.

Thanks again,