|
|
|
|
|
#1
03-20-2003, 08:44 PM
|
||||
|
||||
|
Heat is off-on, monovlave seems ok...?
My heat in my newly acquired 85 300SD is off and on, warm then cool air. I checked the monovalve and it seems ok, no tears in the rubber diapharm. Could it still be faulty but not visible? Or could it be the thermostat that is causing the erractic heat? Thanks.
__________________
85 300CD Signal Red/Tan sold 83 300D Manganese Brown 109K 97 E420 Midnight Blue 197K sold 98 BMW 328i Vert White 100K, sold 95 BMW 525i White 125K, sold 93 BMW 525iT Red 193K, sold 95 E320 Green Wagon 125K, sold 94 E320 White 127K, sold 85 300SD 156K Grey (Annie), sold 84 300D Lapis Blue 170K (Judy), sold 99 ML 320 Black (lease), 1998 C230 White (lease) 00 Honda S2000 Red (lease) 86 Mercedes 300E (sold) 84 Porsche 911 Red (sold), 1965 Porsche 911 White (sold) 
|
|
#2
03-21-2003, 11:36 AM
|
||||
|
||||
|
how warm does the car run at operating temperature?
maybe you could check the condition of the temperature sensor tube in the dash - they often are disintegrated.
__________________
1984 300D Turbo - 231k....totalled 11/30/07 RIP
|
|
#3
03-21-2003, 01:57 PM
|
|||
|
|||
|
Try setting the temp to full hot, this will over ride the sensor. If the air temp is normal (very hot and stays hot) then it's probably sensor related. If you still get hot and cold try it again on full hot when you are driving at a steady speed of 30+/- mph. If you get full heat at speed but not at idle then it may be a bad circulation pump (the electric one). If the temp still varies at speed check to see that the monovalve has power at full hot (you can pull the plug and test for a circuit. I'm 90% sure it's energized at full hot, either way you are testing for consistency).
If the circuit is working properly it probably is the monovalve, if the circuit is on and off then you may have a problem with the climate control unit. Hopefully somewhere in there you'll find your problem.
__________________
LRG 1987 300D Turbo 175K 2006 Toyota Prius, efficent but no soul 1985 300 TDT(130K miles of trouble free motoring)now sold
|
|
#8
04-03-2003, 02:40 AM
|
||||
|
||||
|
The temperature sensor has a tube that goes from the top of the dash down to the sensor. A small fan gets the air to it.
My car did the same thing. The tube from the dash to the sensor was brittle and had fallen apart. The dealer replaced it and everything work fine now. Go check the tube. Dave
__________________
1970 220D, owned 1980-1990 1980 240D, owned 1990-1992 1982 300TD, owned 1992-1993 1986 300SDL, owned 1993-2004 1999 E300, owned 1999-2003 1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD 1988 560SL, 100,000mi, owned since 1995 1965 Mustang Fastback Mileage Unknown(My sons) 1983 240D, 176,000mi (My daughers) owned since 2004 2007 Honda Accord EX-L I4 auto, the new daily driver 1985 300D 264,000mi Son's new daily driver.(sold) 2008 Hyundai Tiberon. Daughters new car
|
|
#10
04-03-2003, 09:24 AM
|
|||
|
|||
|
Before you do anything, pull the glovebox and replace the foam tube that runs behind it. The foam disintegrates and causes air leaks, which will cause the problems you are having. I replaced my tube with some foam pipe insulation from Home Depot. Problem fixed.
GregS '84 300D '90 300CE
|
|
#11
04-03-2003, 09:29 AM
|
||||
|
||||
|
You know, for $20 bucks, I'm going to replace the monovalve. It did wonders for my 300D when I did that...heat o' plenty. I regulate by opening the windows. If I lower the dial, then heat stops. After reading the ACC piece, it's usually the monovalve, then followed by the Control unit which I don't want the replace, more $$$.
|
|
#13
04-13-2003, 03:23 AM
|
|||
|
|||
|
Monovalve
In answer to your question - yes, the valve can be faulty although with a good diphragm. There is a steel spring inside the valve. When it rusts thru you will still have heat when driving on higher RPM but no heat when idling.
|
 |
| Bookmarks |
|
|
Linear Mode
