Constant Hot Air In The Cabin

[newlexman]

Hello Guys,

I wanted to know if anyone else has had the cabin of the vehicle constantly seeming like the heat is on. While im driving i dont feel any fans blowing at any vents but it constantly seems like the heat is being thrown at me, even with the air set to maximum cool but the air will not be on. I dont have heated seats that I can tell and when I bought the car the driver seat is not even hooked up where it can move, no electrical engines on it. But on a hot day you can get in the car and it will be already hot, then when it moves additional heat is being thrown at me?

[glenmore]

This happens in my 1990 also. I'm guessing that the controls that move the flappers back and forth are on the way out. What I do is briefly turn on the AC. This seems to jog the flaps into the correct position and this just about eliminates the hot air.

glenmore

1990 LS400

1991 300CE

2000 C280

[Alexander the o.k.]

Try searching 'heater control valve '. It is located high on passenger side on the fire wall with a heater hose on one side and a cable that runs through the firewall. Pull the cable toward the firewall all the way to shut valve completely. Or as wwest suggests, slip the cable off, and tie valve down. Re-connect the cable in the winter so the valve will open allowing heat into the cabin. If it is faulty, it will also have the effect of warming your ac air while it is running.

http://us.lexusownersclub.com/forums/index...hl=heater+blend

[glenmore]

I actually just replaced this item the other day while I had the coolant level lowered. Haven't had a chance to see if anything has changed. There probably isn't a Gen I Lexus out there where this valve is not encrusted with dried antifreeze. Both ports on the valve were rotted thru, leaving plastic in the inlet and outlet hoses so beware of this if you are changing it out.

glenmore

1990 LS400

1991 300CE

2000 C280

[swordfish]

also check the big rubber strip seal that goes across back of engine bay and seals the rear of the hood against hot air from engine bay being sucked up into the fresh air intakes to your cabin cooling system. mine was missing, probably from a previous accident repair. cost about a 100 bucks oem and you can install in 10 mins yourself

cheers

[oldskewel]

This happens in my 1990 also. I'm guessing that the controls that move the flappers back and forth are on the way out. What I do is briefly turn on the AC. This seems to jog the flaps into the correct position and this just about eliminates the hot air.

glenmore

1990 LS400

1991 300CE

2000 C280

I think this is the explanation. I have a 91 with a relatively new heater control valve, and have the same symptoms.

So I'd call it a design feature. If the heater is set to a temp that causes the heater control valve to open, and then the climate control is turned off, the climate fans turn off, but the valve remains open, keeping the heater core warm. Even with the fans off, driving will cause some air to move through the vents, and it will be warm due to the heater core.

If you don't want this feature, before turning the climate control off, reduce the temp setpoint so that the heater valve closes.

oldskewel

1991 LS400

1985 911