Hi, I know that there are various threads regarding non working heaters, blend controls etc. But I cannot find anything about heater that produces tooo much heat, no matter what settings. Everything would seem to point to faulty blend control. My 199 Blazer is European RHD so I am assuming that the control is still on the right of the vehicle, as in LHD vehicles. Is this correct.

In the short term can I place a control valve in the heater pipes, if so which of the 2 pipes?

Thanks, BooTs

 

Sure sounds like the blend door isn't moving and I would go with your guess that it is on the right side though may be a in a different location due to the steering column.

If you plan on throttling the flow through the heater core I would "normally" say the outlet, but as the heater cores aren't the best when it comes to pressure I'm thinking the inlet.

 

I have been dealing with this issue as well. First things first. Have you checked all vacuum hoses for leaks as well as the 4X4 actuator for a broken diaphragm?
In my case this is what happened. There is a double lipped seal between transmission and the transfer case that went bad. This allowed the transfer case to over fill which in turn also allowed the oil to be sucked up through the vacuum switch on top of the transfer through the lines into the dash which in turn took out a vacuum block switch behind the ash tray. Did you find any slime in vacuum lines when you checked for vacuum? If yes then there is a good chance this has happened to your ride as well. Requires vacuum lines in dash to be cleaned out or blown out etc. and pulling that vacuum block assembly out to look at it.
I read that there is a way to clean the plunger in it or something but I had the shop put a new one in mine. The kid didn't blow out my lines and it sucked remaining oil from vacuum canister back down into the HVAC system taking out brand new block assembly! Yea, I'm kinda mad at the shop for not taking the extra time to clean out lines and the vacuum resevoir and giving me a sauna ride for the last 3 weeks! I'm going to dig into mine this Saturday when I get time. Hope some of this helps you!

 

Thanks guys for your responses. I will check as suggested especially the vacuum pipes etc.