Originally Posted by jeffrylebowski

Hello,

I have had to replace many a monovalve in my 126 over the past 14 years. This fall was no exception as the rubber was torn on my existing one. Ordered a new aftermarket part. Once installed - no heat. I do get heat if I disconnect the power supply and set thermostat to coldest setting. When I do that it blows full heat. Went under the hood today to inspect the new monovalve and the rubber is still intact. Connected power supply and again no heat. I know there are a pile of posts on this but I have a feeling that this could be the result of a faulty crappy aftermarket monovalve?

The Dude.