I'm guessing you mean the heat, when on, does not regulate properly and remains on full heat on any fan setting, while the fan responds to the speed setting. the only way to turn the heat off is to set the system to cold.

This indicates a bad mono valve or sensor system. The temp sensor is on the under steering wheel panel. Check to see if it is hooked up to both electrics and vacuum (hose out the top).

The mono valve opens and closes to start and stop the flow of hot coolant to the heater core. This is controlled by the temp sensor/heater control system. The guts of the mono valve leak about once every couple years. It has a rubber diaphragm that rips. Replacement is easy, unhook electric and 4 screws pull out old, drop in new. Part is 22-45 bucks depending on what and where you get it.

• New to Bimmerboard (pic) - euro635gas 2005-09-23 22:02:46 (763 views)
  • Re: New to Bimmerboard - kjkumar 2005-11-18 14:05:57 (388 views)
  • The car is nice but that ocean view has to go!!! (nt) - cmdbmw 2005-11-16 19:28:31 (385 views)
  • Well let me be the first to say, 'welcome aboard!!' Awesome looking car!! - Andrew Elmore 2005-09-24 17:26:48 (464 views)
    • Re: Well let me be the first to say, 'welcome aboard!!' Awesome looking car!! - euro635gas 2005-09-25 22:48:05 (465 views)
      • Where are you located? (nt) - Andrew Elmore 2005-09-25 23:53:11 (471 views)
        • Oregon - euro635gas 2005-09-26 13:37:07 (484 views)
          • John, tell me a bit more about the full heat situation...> - kff 2005-09-26 20:33:42 (513 views)
            • Defrost question - dupesq 2005-10-11 11:17:51 (432 views)
              • Possible answers - euro635gas 2005-10-13 15:21:08 (527 views)
                • Re: Possible answers - dupesq 2005-10-14 15:15:48 (426 views)
                  • Need a switch? - euro635gas 2005-10-14 23:49:02 (426 views)
                    • Re: Need a switch? - dupesq 2005-10-29 21:44:40 (364 views)
                      • Used Switch (nt) - euro635gas 2005-11-03 23:07:48 (342 views)
                        • Used Switch part 2 - euro635gas 2005-11-03 23:09:45 (346 views)
                          • Re: Used Switch part 2 - dupesq 2005-11-07 11:31:57 (404 views)
                            • Call toll free 1-800-650-8814 - euro635gas 2005-11-07 17:06:26 (337 views)
            • Oh No another mono valve - euro635gas 2005-09-27 01:18:50 (394 views)
          • Mine is actually doing the same thing. - Andrew Elmore 2005-09-26 17:50:38 (412 views)
            • Re: Mine is actually doing the same thing. - euro635gas 2005-09-26 18:52:41 (442 views)
              • If you happen to have one, id be interested. - Andrew Elmore 2005-09-26 20:12:13 (412 views)
                • Bosch or Sofica? - euro635gas 2005-09-27 01:25:26 (455 views)
                  • I think it was Bosch the last time i checked. - Andrew Elmore 2005-09-27 14:36:58 (383 views)
                    • Andrew Pic of Rear Wing (pic) - euro635gas 2005-10-09 21:47:34 (495 views)
                      • Nice lookin wing, never seen that before. (nt) - Andrew Elmore 2005-10-10 15:55:10 (433 views)
                    • Good thats most common - euro635gas 2005-09-27 15:20:51 (398 views)