Hi,
My car doesn't blow any heat but cold air (warm air under the steering wheel) the heat worked great the day before. I did my research here and some said that i should replace the mono valve. I am wondering if anything i can do to test and make sure that the monovalve is going bad or not.
And i am wondering what is the MPG on this car?
someone from ebay ad said he can have a 23MPG.... and mine is only 14-18... a huge different!
thanks and look forward to hearing from you guys!

I discovered my mono valve was bad by driving the car with the heat on (which was only blowing cool air). I stopped the car for a few mins, started it again and hot air would blow for a minute or so, then it was back to cool. It seems the warm air from the engine was blown through...

14-18 mpg is about right. I get 12-15 city driving and probably around 20 mpg on the highway.

I have a similar problem on my car. There's heat in city traffic and no heat on the freeway. If there's no heat at any time, it could also be a bad cabin temp sensor.

Aparently the monovalve is easy to repair/replace. It's under the ABS controller on your car. I'll know more when I fix mine hopefully this weekend.

Sixto
91 300SE
81 300SD

Thank you guy, guess i am going to get the monovalve first and see if it does the trick.
So the monovalve is located under the ABS controller?
not somewhere near the battery?

My 1987 560SEL has the same problem. Let me know if the monovalve replacement is the cure. Thank you

Also my 560SEL averages about 15-17 MPG.

The monovalve is between the battery and ABS controller. The ABS controller is that box or one of those boxes on the firewall just ahead of the wipers.

Sixto
91 300SE
81 300SD

Hi Sixto... so you are also from the bay area right? are you a DIYer? i don't know nothing about my car and if you don't mind... i really want you to teach me how to take care of my car and what kind of works are so easy that i can do by meself...
thank you very much!

jchowe420,

Check your private messages.

Sixto