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Heater contorl unit repair.


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So i have recently taken apart my dash in hopes to fix my heater controls. Current problems are: Only the 2 highest fan speeds and only blows on the BI-Level. ( i did replace the knob sensor for the fan speeds, but no change. Oh and put in another used heater blower motor with no change)

 

Not huge issues cause i still have hot air though. But it rained and made me realize i need a defrost function still. Those little vacuum lines dont seem to be pinched that come off the back. Maybe when i re assemble it they become pinched? Anyone have any luck with these issues?

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i had a similar issue. (still have only 2 speeds on the blower) but there is a vacuum line coming off the engine to a resonating container. Mine is a ea82 wagon, so it is on the passenger side just next to the firewall. you might try looking around there and see if the vacuum line came off. there are 2 on the resonating container, 1-in, 1-out. Just a thought

 

 

-Justin

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fan speed issue is because of broken resistors in the resistor pack (bolted to the blower box under the glove box). This is very common....I found a new resistor pack on ebay a while ago for a reasonable price....but I'm sure it'll fail soon as well. Someone had a write-up years ago about soldering in some better resistors that don't heat up and fail as easily.

 

 

the other is a vacuum issue. start by tracing the lines in the engine bay (as crazyman suggested). it's not uncommon for that line to slip off the intake manifold.

 

There's a little metal guard over the lines to prevent pinching...so that probably isn't your problem. if you know you're getting vacuum to the switch, it could be the switch itself. it's a fairly simple mechanism, with little sliding plastic pieces, if these don't seal (there's some sort of grease on there that helps...but it seems that it usually dries up), you'll have problems. I tried a few different switches, with no luck.....so I did this:

http://www.ultimatesubaru.org/forum/showthread.php?t=66673

 

that was 3 years ago. still running it like that. always just on Heat and Defrost. which works fine. I think I'll try the switch from my parts car in it before I sell it though.

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well, it doesnt actually do the "switching"; think of it like a air tank. it's pressurized....ish. the actual switching mechanism is the control itself. When you switch from one mode to another it re-route's the vacuum tubes to open and close certain "doors". Physically too i believe. that resonating chamber simply supplies a constant pressure/vacuum so that the control can do that.

 

 

-Justin

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