I just recently changed my thermostat out (car over heated) and now my heat barely throws out any heat the blower sends out mildly warm air I burped the system and it didn't seem to help. I was thinking it could be the heater control valve..... Were would it be located on a 91 l03? Thanks

 

heater bypass valve is located right next to the engine on the passenger side.

what temp tstat did you install? and you said you burped the system. how exactly did you do it?

 

I got a 195 oem tstat I ran the radiator with it open for a while and let the stat open and close and filled it up with water

 

run the engine with the rad cap off until the tstat opens, then fill to the top with water and put the cap on. letting the tstat close before filling defeats the whole purpose.

 

I've never switched one out anything I should know before I attempt to swap it out?

 

the heater diverter valve? you just unhook and hook everything back up. chances are its not the problem.

 

Then what would be the problem?

 

most likely low coolant level. the heater diverter valve only restricts the flow of water to the heater core when you turn the ac to cold. if it malfunctions it doesnt do anything when you turn the ac to cold and the ac blows just a tiny bit hotter than normal. with you getting only a luke warm air it points to either low coolant, or an obstruction in the ac box under the dash.

your fan blows full speed right?

 

Yes it blows full speed.

 

then id double check the coolant level by leaving the cap off and running it til the tstat opens.

 

Lol I did that all ready its slap full of coolant

 

then you either have an obstruction in the ac box or an obstuction preventing decent flow to the heater core.. apply full vacuum to the heater diverter valve and see if it gets any better

 

Did you have heat before?

 

Yea I had heat before just changed the valve and it didn't make a difference.... How do I apply full pressure to the valve?

 

You may have an air-lock

turn your heater on, with engine running, keep adding water as air is displaced...have the cap of radiator out...naturally do so with a cold engine..keep running your heater at max. and just keep adding water at radiator..after several minutes all air will be out..you will notice that bubbles will stop and water will look calm at top of radiator orifice..good luck

 

I'll mess with it more tomm ill post the results. Thanks everyone for the help thus far.

 

My heater control valve connections cracked open due to age a few weeks ago. The symptoms were no settings on climate control (every thing was Defrost, max, norm, htr, vent)

 

Ok so I ran the heat with the rad open...and let the retarded open it burped and filled it back up with water....still only semi heat. I'm totally lost on what to do.

 

you might have a blackage somwhere. under the dash and pull the ac box cover off and take a look(its not that hard). you can also tell if the heater core is getting hot.

 

Guess ima replace the radiator core next weekend.

 

I think my problem was solved when I got home from work I decided to back flush my heater core when I did that I saw some nasty brown stuff fly out the hose I flushed it a few more times until it became clear. My heat is working decent now. I think a radiator flush is in my near future even though it looks like a newer radiator.

 

A radiator flush is always a good idea imo. When i got my Formula the antifreeze was ORANGE from rust!!! No telling how old it was.