kenmonster

iTrader: (1)

hey on my 94sc400 when i turn on the heat it to maximum it will blow out cold air, so i replaced the thermostat and the air is definitely warmer than it was before but it is still not even close to hot at all, i checked all the hoses and they have seals in the engine all the fuses are good and i cant seem to figure out why i get no heat, the engine is warmed up fully and still no heat, any suggestions?
thanks

mitsuguy

iTrader: (2)

heater control valve or blend door...

heater control valve lets the warm/hot coolant from the engine flow into the cabin in the heater core, where air flows over it and is heated... if the valve is closed, and does not open, then no hot water into the heater core... also, could be the blend door - it's a door that lets air pass over either the heater core or the a/c evaporator core, depending upon what you are requesting...

kenmonster

iTrader: (1)

thanks mitsuguy, do you know the locations of the heater control valve and blend door? if possible pictures?

VVT-i

The SC is bad about the heat control vacuum switch valve located on the passenger side/right side of the firewall. If you open the hood look on the right side of the firewall you will see heater hose that go inside the car and a small vacuum switching valve with 2 short vacuum hose. The little valve always goes bad on the SC.

Papi

Any idea where to get one. Or perhaps a P/N.

kenmonster

iTrader: (1)

thats the problem i connected the two hoses byoassing the valve and instant heat!.. will it cause problems if i leave it hooked up like that untill i can find another one? thanks!

VVT-i

You will be o.k, but just a PITA to adjust the temp. from Cool to Hot. The little valve just switching the position of the heater control valve. You may need to check on the Weather Channel a little bit more...

VVT-i

Welcome to CL. I really don't know the P/N and price. You can search for our vendors such as SewellLexus or Lexusparts.

kenmonster

iTrader: (1)

sorry what does "PITA" mean?

kenmonster

iTrader: (1)

http://www.sewellpartsonline.com/par...d=158832&all=Y
im almost 99% sure thats the part we need

VVT-i

PITA mean Pain In The A.... If you want to change the temperature you will have to open the hood and reconnect the valve to the opposite.

kenmonster

iTrader: (1)

ohhh lol just realized that..and alright thanks

dirkdiggle

iTrader: (1)

I think my heater control valve might be bad or stuck closed!

- the blend door is working
- coolant is full
- no air traped in system

Has anyone had any luck getting there heater control valve to work after it stopped working???

Maybe just move the little arm/valve by hand a few times and it may start working again?????



I really do not want to spend $300 on this part!

kenmonster

iTrader: (1)

yeah i went to a local junkyard and got lucky, they had a 92 sc400 in the yard.. so i got the valve and they charged me 20$.. brought it home and installed the new one and i have heat!
check with local junkyards for the control valve a

UpInTheLex

iTrader: (5)

I'm having similar issues.

At this point I feel that air in entering my cooling system somewhere, not allowing for a compete vacuum.

My heat is RPM dependent. At 900rpm it blows cold air, at 1500 warmer air, at 3000 the air is HOT.

My valve is working properly. I tested it by turning on the heat and feeling the backside of the valve to ensuring the vacuum is pulling it closed. When cold air is selected it opens as normal.

I'm almost certain the heater core has finally opened up large enough to let enough air in to cause problems.

Otherwise I'd say its a radiator cap.

The overflow was bone dry, I added coolant and it won't get pulled into the radiator, so there must be a air leak somewhere.