BrokeEF

Hey guys, I was driving my SC this morning and I had the climate control set to 75. It seemed like the air coming out was cold, so I turned off the AC (though I think that is auto as well?) and turned it up some. Still pretty cold air coming out, so I went all the way, and the fan still only went to 2 bars, and the air was still the same temp coming out. The car was fully warmed up by this point, but even if it wasn't I would assume that the fan would go all out trying to warm the car up. I am not very familiar with these cars yet, and the normal sequence of operation for the climate control.

So first up, was the climate control working the way it should?
Why am I not getting any hot air out of the vents?

I would need to look back through the receipts to see if the heater core was ever changed, but I would assume so being a 1993. If not maybe its plugged? Would I be able to see the valve that allows coolant to go though the heater core so I can see if its actuating? Any help is appreciated guys! The car is a 1993 SC400


Thanks!
Sean

t2d2

iTrader: (8)

No heat would generally mean a bad or bypassed Heater Control Valve (visible in the engine bay on the firewall). However, not being able to increase the blower speed indication suggests that your HVAC unit is bad or the wrong part number for your year. To confirm the part number, you would have to perform mild surgery like if you were doing a stereo install.

BrokeEF

I guarantee 100% that nothing is bypassed, and there are no incorrect parts installed. I can increase the speed, and it will go full blast on auto when in the colder settings. I want to say that I have had it go to full speed on heat once before, but I am not 100% positive. I will have to look at the valve on the firewall and see if its moving as it should to start.

Sean

estomax

iTrader: (2)

if heat isnt coming through the vents you are low on coolant, that was the symptom with my sc400. go top off the radiator and you should get warmth again.

BrokeEF

Its not low on coolant.

Sean

CoOl21

Heater core clogged?
Just a guess, I might be wrong.

Zerodrag

iTrader: (5)

No sure about the bars on the control unit, but if your temps from the vents seem to fluctuate, or does not decrease/increase when you turn the ****, it may be the heater control valve on the passenger side firewall starting to go out. When mine was acting oddly, the valve showed signs of coolant weeping from it. Though not guaranteed to be a sure sign of failure, it's a place I would suggest starting with. I believe if you have someone help you adjust the climate control temp while you are looking at the valve in the engine bay, the arm should move corresponding to the **** being adjusted.

BrokeEF

Yeah, I am less concerned with the fan not going up when I turned it up since I am getting a LXCC soon, I was more just curious. I will have to check the valve when I get a chance and go from there.


Sean

t2d2

iTrader: (8)

How do you know that for sure? Have you inspected both? You've only been a member here for 3-4 months, so I'm assuming you haven't had the car for long. Previous owners have done lots of crazier things.

BrokeEF

I don't know what my having been a member here for 3-4 months has anything to do with anything, I know because the car is immaculate, and has a very VERY long dealer history from the single owner. I am talking paying the dealer for regular maintenance such as washing the car, all oil changes, brakes, tires, along with things like replacing the speakers (months ago), replacing the door hinge, and so on. This doesn't guarantee anything of course, and I will still inspect these things, but I would be VERY surprised to find anything like that on this car. I should look though the stack of receipts and see if/when any of these parts were replaced. Like I said, I would guess the heater core has probably been done in the cars 23 year life.

Here is an engine bay shot just because. Tell me you wouldn't be surprised to see bypassed heater controls in a car this clean from Chicago.




Sean

Halon

iTrader: (6)

See posts 3 & 4 here. It's a quick test you could do. If your heat comes back, then you know either that Vaccuum Switch is bad, or its not getting the signal from it's source to toggle on.

https://www.clublexus.com/forums/per...rol-valve.html

t2d2

iTrader: (8)

No need to get offended so easily. It has to do exactly with what I said, nothing more nothing less. Recent membership implies recent ownership, which in turn implies limited first hand knowledge of what has been done to the car.

And I wasn't wrong. That's a far cry from, "I guarantee 100% that nothing is bypassed, and there are no incorrect parts installed." The car does look clean and well maintained, so you likely are correct that the HCV wasn't bypassed by a P.O. But, when you're asking for help, it doesn't make sense to rule out possibilities before even exploring them.

BrokeEF

So I ended up trying this last week, and it sort of worked. So lets start with the controls since that seemed to throw people off. If I turned it just to max temp, the fan would go to speed 2. However, I found later that if I turned it to defrost it would go full speed. When I bypassed the actuator and got some heat, turning the temp to max would make the fan go full speed. Seems like it wont just blast cold air, it waits until it sees some temp in the heater core (or something) before allowing the fan to ramp up. I kind of had a feeling that was how it worked, and it seemed to be true once I could actually get some warm temps into the system.

Getting back to those warm temps, it only ever got kinda warm. Not sure now if the valve didn't open fully, or if the heater core is clogged. I will investigate more sooner or later, but at least I know the actuator is bad for a start. I will probably change that and see how it goes after I get that in. Ill keep you guys posted.


Sean

rdm20fan

You are low on coolant, and you need to bleed the system.

RXRodger

iTrader: (2)

Check that you have vacuum lines all in good order. If you bypass the VSV and just actuate the valve via a vacuum source and you get full hot at least you rule out the water side and the actual valve itself, can concentrate on vacuum, the VSV, or controls. You should be able to see the valve actuate based on going from full hot to full cold also, it's just a quarter turn ball valve.