auxiliary pump problems with new climate control unit w220
 

The auxiliary pump tracing shows no ground! Is the ground supplied by the control box or where?

Directly wired the auxiliary pump jumps to life and controller is supplying power.

I just installed a rebuilt climate control unit and now the unit clicks every minute and turns off the fan for a second and than turns it back on for 30 seconds.

I swear I can feel just the smallest amount of heat, but it is very slight.

Also, the a/c stopped working. I have not tried to readjust the feedback potentiometer yet, but a/c worked with old system fine.

W220 190E 1990 2.6 I refer to rebuilt climate control unit notes at:

http://www.programainc.com/files/10985.pdf

To start with that is a W201 chassis... you need to check (OR have checked) the current draw of the auxiliary water pump. should be around 1 amp. measure for at least 1-2 minutes. That controller will go into a "limp" mode if current draw is too high.

auxiliary pump problems with new climate control unit w201
 

The current draw of the auxiliary water pump is .25 amp both direct from battery or from the controller. However, the ground wire from the controler has no circuit and it had to be supplied.

Even unpluged the controller continues to shut down the fan about every 30 seconds for a second.

What is your best guess, as the next step?

This is from the 1987 model year info...sounds like the feedback pot is the problem....