This afternoon after cruising at about 70 mph for about 30 min with cooling sys doing very nicely - lowing nice cold air, immediately when I released the accelerator to exit the interstate, the heating/cooling sys started blowing very hot air. Is it possible that when I released the accelerator, linkage somewhere may have caught a vac tube and pulled it loose, causing the heating/cooling valve (Is it mono valve?) to switch to "HEAT". After getting home, I checked for loose tubes under hood only briefly before being chased inside by thunderstorm and darkness. BTW, earlier in the day, I had isolated door lock system at "Y" connection (2 yellow tubes) near the brake booster. Tranny shifting is still normal. Compressor engages. Any ideas? TIA

------------------
Wilton Strickland
Goldsboro, NC
91 350 SDL. 81 300D

I forgot to say I was driving the 81 300D! 'Sorry. It's the 123 suddenly blowing hot air on deceleration & unable to get to cool since.

------------------
Wilton Strickland
Goldsboro, NC
91 350 SDL. 81 300D

I should have read some of the previous posts on this subject before jumping in with my questions so quickly! I realize now that its the mono valve that controls flow of coolant to heater core. Evidently, something happened when I decelerated to cause mono valve to loose elec. power and open fully, allowing heater core to suddenly fill with very hot coolant. Valve is still open.

------------------
Wilton Strickland
Goldsboro, NC
91 350 SDL. 81 300D

Investigation this afternoon revealed very dead battery and non-charging alternator. I tightened alt. belt slightly, and all is back to normal - at least so far.

------------------
Wilton Strickland
Goldsboro, NC
91 350 SDL. 81 300D

Be sure to check the brushes inside the alternator. If you catch them before they damage the armiture, you will save a bundle.

------------------
Benzmac:
Donnie Drummonds
1992 500E (very soon I hope :)
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM