Blower/ Heater problem??

[theGOODWIN2012]

Alright so I really am not sure whats going on here. It seems as though my car is blowing heat out of the vents while I am driving even if the fans are off. It seems to be less noticeable when I put the system on circulate. Not sure if maybe air is being forced through the system? Wouldnt even know how to go about diagnosing this because Im not really sure whats going on. Thanks for any help.

 

[Dan_Gyoba]

Check operation of the heater VSV. Some of those are bypassed so that the heater valve flows full time regardless of if the climate control wants it on. That means that the heater core is hot, so...

I believe that it's normal for there to be some airflow even if the fan isn't on.

 

[theGOODWIN2012]

So maybe the solenoid is stuck open? Because the amount of heat coming out of the vents with the fans off is pretty substantial. Now Im also wondering if this has to do with why my a/c hasnt been as cold as it was a few weeks ago. Maybe the heat is still slightly on. HMMM. Ill investigate more tomorrow but thanks for the help.

 

[GrimJack]

That valve is normally open unless you have the temp turned to full cold. Also, if you have the controls set to recirculate and the fan off, no hot air should come out of the vents. If you leave it set to outside air, even with the fan off, some air will flow, and because there is always hot coolant circulating in the heater core, it will be hot.

 

[theGOODWIN2012]

Well thats the thing. I need to check to see if the valve closes when I have the ac on and it set at 65. But even with the system on recirculate Im still getting hot air blowing in. Less then if the system was on fresh air, but still enough to make the cabin quite uncomfortable.

 

[Poodles]

Seems to be a common "issue" on these cars, and it's simply because the base of the windshield (where the fresh air is taken) is a high pressure zone, and the heater valve never truly closes all the way. Add in old seals around the various components in the climate control system and it's going to be drafty. Any car will do the same thing given the circumstances.

I'm betting you don't have A/C...

 

[Nick M]

It seems to be less noticeable when I put the system on circulate. Not sure if maybe air is being forced through the system?

This much is normal, on almost every car. Even recirculate does not fully shut off the outside air. In the US anyway.

 

[Dan_Gyoba]

I'm betting you don't have A/C...

I need to check to see if the valve closes when I have the ac on and it set at 65.

I'll take that bet.

I've verified that the valve closes on my cars with the climate control set at lowest temperature (18C). I doubt that it 100% closes, of course. I also get some "heat" while just starting out, on hot days, which I attribute to that nice black cowl sitting in the sun. It goes away after a bit of driving though.

 

[theGOODWIN2012]

LOL^

But I took a look at the vsv after a little more research on it last night and have confirmed that its most likely broken. Since no matter what I do with my climate control it stays in one position.

It may have went sometime between when I had my system recharged and when I started noticing the heat problem. Obviously.

 

[Dan_Gyoba]

Does it close when the car is off? If not, then it's more likely that the water valve is stuck.

I watched mine when I start the car. It moves when there's manifold vacuum to the up position. When the climate control is turned right down, then it goes back down again.

 

[theGOODWIN2012]

Mine is always up no matter what I do with the climate control or if the car is on or off. The only way I get the valve to close (or go down) is to disconnect the vacuum line. It seems to hold the pressure even after the car is off until I disconnect it.

 

[3p141592654]

Just the heater valve on won't make it blow hot air. Temp regulation is done through the control of the air mix door. Assuming it is not just heat soak like poodles described, then the air mix door servo and control system needs to be tested. Unfortunately, these cars have position sensors on the air control doors and when they wear out the system loses control. It is not a cheap fix if that happens. Could be some other fault like a bad air temp sensor, etc. You need to troubleshoot it.

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=AC&P=9

[url]http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=AC&P=42
[/URL]

 

[GrimJack]

Sounds like the electrical VSV underneath it is frozen. It's supposed to switch between vacuum and atmospheric sources when told to by the climate control. You can test it pretty easily, just wire it to 12v and check if you can blow through it, then disconnect, and see if you can still blow through it. If it's the same both with 12v connected and without, it's dead.

Or what Pi suggested. The VSV is prolly cheaper than his suggestion, but not by much, damn things are still ridiculously expensive for what they are.

 

[theGOODWIN2012]

^^^^ I just read that in some other forums while trying to find a solution. But 99% of the problems people are having are not having heat. When my heat works great. Ill definitely try this out though. ((And damn youre not kidding when you say expensive for what it is)) :aigo:

 

[Dan_Gyoba]

There's a Mercedes Benz part which works great for that VSV and is less than half the price (Or was in 1998 when I bought mine) Mercedes Benz part number 001-540-86-97 (It's worth looking into.) That's the part that I've installed in my '89. You need to clip the wiring harness from the stock unit. I used butt splice connectors to fashion a jumper to the MB part, or you can buy the MB connectors 008-545-11-28 and 008-545-08-28 -- I didn't. The only disadvantage is that the MB part doesn't mount to the factory location, it has a 2 bolt flange which I zip-tied to the factory VSV mount.

This is, of course only if it's the VSV that is at fault. I don't think that it is, since the valve opens. Typically when the VSV fails, you get no heat at all. TEST THE VSV BEFORE YOU BUY A REPLACEMENT!

I'd definitely check if it's the heater valve. It really should close when temp is at min setting. While I know that the VSV does indeed fail, this doesn't sound like it to me.

Yes, the heat selector should direct air away from the heater core, but if your AC blows cold at all, it's probably working. This is also definitely worth checking.

 

[theGOODWIN2012]

Okay, so Im doubting that its the VSV and more of the heater valve. 1 because I'm still getting heat when I set the climate control to higher temps, and 2 because all the sensors are working. Finally once I disconnect the vacuum line running to the top of the valve the valve closes, thus when Im driving Im no longer being melted.

 

[3p141592654]

Have you verified correct operation of the air-mix door with temperature setting control? The heater water valve is an off/on thing, it is not used to regulate temperature of the air. You will still get cold air with the A/C on and the water valve on, just that it will be about 10deg warmer than normal.

1 because I'm still getting heat when I set the climate control to higher temps,

That would be normal behavior, unless I am misunderstanding something!

 

[Nick M]

That would be normal behavior, unless I am misunderstanding something!

More pie?

 

[3p141592654]

More pie?

It's the only thing on the menu!

 

[jetjock]

Which is why I'm not in this thread. I know from the git-go when to steer clear. It's not that hard actually.