RowlandTaylor

1998 SL500, r129: Have very little air coming out of the dash vents. Plenty out of the defrost and the floor.

The dash vents indicator light on the controls does not light up but the defrost and floor and combination of those two does.

Suggestions before I buy the control unit??

MercedesTheBest

id check for a loose connection. those units are very expensive so you don't want to have to buy one if you don't need too.

RowlandTaylor

Thanks. Will check it out this weekend.

BJonesFL

First, the lights in the control unit and under the thumb wheels are simple to replace; set that aside for now. About the 3 thumb wheels, when you turn the center wheel slowly from open to closed (high to low) what happens to the airflow in the center vents?

The Climate Control Unit has both on-board real-time and stored operating values and error codes that will help you find the problem(s). The diagnostics can be run in less than 10 min by your service provider, dealer or independent. If you don't like that idea, pm me with your email address and I'll send the instructions to you. You may be able to find the same instructions on this forum using the 'advance search' option on the term 'climate control diagnostics'.

So check the thumb wheel operation first, then use the search tool for diagnostics instructions, last, contact me directly and I'll send them to you. Then we'll do your lights

Bob

RowlandTaylor

Thanks for the info. I'll check the advanced.