I went out in the Mondial today, the first time I've used it for a month. When I first got it last May the heater was reluctant to produce hot air, it kept going cold. However the car had not been used much for some years, only 1500 miles since 1997. This fault cleared up and the heater was fine all Summer (hot/cold/air con all OK) Today it was stuck on full hot and I had to turn it off. Eventually it did return to normal but then it stuck on full hot again, only rectifying itself as I pulled onto my drive. What's the most likely cause of this fault?
Much as I love the Mondial T, I'm glad for the simplicity of my 308. Picture from Ricambi* - just too much stuff! Going through the parts list, #41 is the 'electromagnetic valve' or hot water solenoid in English, highlighted which is hosed from radiator plumbing to the heater core. The difficulty has to be your solenoid not operating per command and a just plain sticky $600 lump. OR an electrical malfunction controlling the solenoid such as a switch, sensor, or poor connection plotting against you to control the water flow you rightly deserve. Possible causes include switch contacts, bad sensor, or stuck solenoid valve and an ECU. However, if your car is secretly monitoring FChat, it will devise something else to spite you, testing your proverbial mettle. Plus I suspect your car was built around everything in that diagram, making it near impossible to get to. If I were troubleshooting this, first step would be to connect a long zip cord to the wires at the solenoid. Then monitor the voltage to correlate whether solenoid was getting told correctly or not acting upon the control voltage it was given. GL *http://www.ricambiamerica.com/parts_catalogs.php?M=FE&P=&V=diag&I=1991 Edit: Found the second drawing in the 660Mb Mondial T workshop manual which pinpoints location of the suspected errant solenoid. Page I2, or page 167 out of 652 pages. Workshop only mentions the ECU only in passing. Image Unavailable, Please Login Image Unavailable, Please Login
That heater control valve is common to BMWs of the same ere. You can get a rebuild kit for it for about $50 from AutoHaus AZ. There is a rubber diaphragm in it that turns to goo and prevents it from working. http://www.autohausaz.com/search/product.aspx?sid=kxmn3iqg4b2osmiiwzf4hz55&makeid=800003@BMW&modelid=1012341@535I&year=1986&cid=24@AC%20%26%20Heat%20-%20Climate%20Control&gid=6860@AC%20%26%20Heater%20Control%20Valve Removing it to do the work is a major PITA, it's up by the passengers right foot in a 3.2, and the cooling system has to be drained. Check to see if the T is the same, I don't know. Once the valve is out, replacing it's innards is a simple task. When operating properly at mid-temperature, it should make a quiet thumping noise as it opens or closes. If I recall correctly, unplugging it should make it go to full hot. You can test that way, or by attaching a multimeter to the wire to see if it is cycling correctly, i.e. it should go between +12v and open when the system should be producing a medium amount of heat. That should test the information it is getting. I've gone through this with my 3.2, so I'm happy to help any way I can. I don't know how similar the systems are, though.
Thanks for the advice. I'll start by checking the valve and it's power feed. When the heater was working last year I could hear the quiet thumping noise from the valve.
I just ordered the repair part from Autohaus Arizona. Thanks for the advice. Price was $90 including shipping, that's about £55 UK. A lot cheaper than a new valve. They take payment by PAYPAL too, which makes it even easier.
