Well I've read all the other posts I can find and still have no answer as to why my heater is inop. The heater control valve is functioning properly. But just to be sure I removed it completely and installed an elbow fitting in it's place. Still no heat.


Coolant is topped off. Also is there a sensor on the radiator I can jump/bridge that tells the computer is the radiator is full of coolant or not? I am full of coolant but if the sensor is bad this could be causing my problem right?

I checked the lines going in and coming out of the firewall and they are hot. No leaks inside the car? So what could my problem be?

I'm leaning tword the "flapper" door that the Temp control unit uses to ration out cold and or hot air or a mixture of the two? If this door was stuck somehow on full cold it could be the root of my problem right?

Where is this valve?

I think I might have this problem. Is it behind the radio? ANyone know if I can disconnect this door and manually move it?

I'm stumped on this one....

Also if it matters I have a boost logic auto installed. This causes a check engine light. Or so I was told. Could this be related? Like maybe the coolant temp sensor on the transmission?

Shouldn't there be a way to bypass the sensors etc and force this thing to spit out hot air? Winter is kick'n my butt here in KS!





Any help is appreciated.

 

Also, where should the OEM temp gauge sit durring normal operation? Mine is about 1/4 of the way up from the cold position. This makes me wonder if the car is ever getting up to normal operating temp. Could this cause the heater not to work?

 

What year and model SC....nevermind Sc400 92'

lemme look

 

Mine sits a hair over halfway at fully operating temperature

Jonny

 

Same here...

I'm going to pimp out a buddy here...PM Dmitry...(97-SC300)
he re-did his heater core and has a pretty good idea of how to go about ripping apart the dash to get at that valve.

 

Sorry, the car is a 96 sc300.

I'll look into why the car is running so cool. I'm guessing it doesn't have one. Probably just need to put a factory Thermostat back in.


neurocity I tried to PM Dmitry, he is not accepting PM's... From me anyway! Ask him to shoot me a PM or something.

Thanks all.

 

I don't think your sensor for the coolant level is screwed up because if it thought you were low than the little coolant light would come on (looks like a carousel or building with columns or... a radiator ).

I sort of have the same issue but the heat comes on eventually. My temp gauge will set at 1/4 temp and than for a little time go to normal operating temp (middle) and drop back down to 1/4 when it's been driven for a while. I'm guessing my coolant has some bubbles in it but it's too cold to try to work it out and I swapped my SC for my mom's ES for the winter. I also had my cluster redone by OLT (when he still owned Lextech Lighting) so maybe my needle sits that way because of that as well (when the engine is off the needle sits 1/4 below the lowest starting mark).

 

Wow, didnt think Dim was that busy of a PMer...Check out his Heater Core thread...He took a bunch of pics.

 

Just a little up date, still no fix though.

I replaced my thermostat with a new 180* unit today. There was a 97* thermostat in there now? I've never even heard of one so low but it was stamped right on the thermostat.

I reset the ECM and went on a cruise. Temp gauge goes right to the middle now and hovers there. Doesn't move much. On my 30 min drive I got on it a few times and my check engine light still hasn't come back on. But my OD light is still flashing. (BL auto trans issue)

Anyway The heater still blows cold. So I'll pull apart the dash today and take a closer look at things.

 

Alright I fixed it! Well sorta... I found the valve unclipped the rod and moved it by hand and now the heater works great! I also noticed that if I push the recirculate button on the AC controls the flapper door doesn't work either. I would assume my environmental control box crapped out on me. But for now I'm happy to have heat! Heres a little write up to help anyone else with these problems.... AND IT WASN'T THE HEATER CONTROL VALVE OR LOW COOLANT!

So you'll be looking at the pass side of the car for this. Basically you need to remove the glove box and kick panel.

Like so...



Then zoom in a bit to the lower LH side close to the console....



Pull the carpet back and stick your head under there....



You should see the valve sticking out right at eye level with your head under there.



Now use a flat blade screw driver and unclip the plastic rod arm holder. The alve should now move freely by hand.

 

Awsome! You got this licked too! You are the man! Glad it is a simple deal. Maybe I should have kept her and just paid you to fix her up. LOL

 

LOL... I'll trade you anytime!

No way man, she's mine now! We gotta line'm up at the drag strip in the spring when I'm done.. 25lbs and some drag radials outta do it!

 

25lbs boost, I'm pretty sure my 1uz wont stand a chance! That car already ran great! I am excited to have another local performance SC enthusiest.

 

I finally found the culprit. There is a check valve that was mistakenly connected in opposite direction. I can provide a picture if you guys need it. It took me a while because I concentrated inside the car by the firewall checking all control assembly and associated components. If you need help, a detailed of what I did pls. donot hesitate to ask. My heater works now.....


I have the same issue with my 92 SC300 and wonder if what you did will resolve it. Do I really need to remove the glove compartment to access those items? Thanks......

I bled the air and topped off my radiator. I have a brand new radiator and thermostat. I found the relay (a black box similar in size to a zippo lighter) that opens and closes the vent. It is working. I found identical control that opens and closes the valve. It works as well. I set my temp. to MAX and fan to max but no hot air is coming out.

 

I have NO idea why I didn't see this thread at the end of last month and would have saved me tearing out half my dash.
I am really depressed right about now LOL... O well all the interior trim got a good scrubbing anyway.

Yes I would imagine it would be better to remove the lower part of the glove box and will take all of 5 minutes to pop loose. Changing that piece is a different story. There are three screws securing it to the bottom of the heater assembly. One is located right up by the firewall with less then an inch of clearance room. Also the wiring runs to God knows where up behind the unit.