heater only works on Max hot

[tomr]

In my 91 V8 (emv model), i only get heat when max hot is selected.


looking at the VSV valve, it only energises when Max hot is selected.


It should energise with the temp knob ~ half way

What is the problem??

 

[spf_lexus]

You know what? I have always had weird heating issues... on cold nights i have to max it out... run the car hard for 30 min or so and THEN it decides to warm up, until then its freezing cold... no change at all. I also notice that my floorboards get a little hot but that could be due to the multiple holes drilled thru firewall. Any luck w/ yours?

 

[tomr]

Hi, i have a replacement climate control ECU to try.

I beleive it has to be in the ecu. ( probally just leaky electrolytic caps) the vsv doesnt energise until you go to max heat. you feel a detend on the temp knob when you go to max and i beleive this supplies the 12v to the vsv, overriding 12v that should be supplies when just on "heat".

will post again when i have tried the new ECU

 

[Peewee]

With Toyota auto heaters (at least the earlier ones) they rely on the outside temp sensor, and the inside temp sensor(s) to judge how much heat is required.

If any of these sensors are unplugged it defaults to max heat.


Although this doesn't sound like the problem you are having...

 

[1UZPWR]

the interior temp sensor not only needs to be plugged in, but also, there might be a plastic tube running to it that needs to be connected

i don't know if the SC has that, but other lexus models with auto climate control do have that, and if it's not connected, the temp goes all crazy.