Not enough defrost to windshield

[Omicronmike]

My 88 LE tends to fog up during the winter when snowing out because not enough air is blowing through the vents at the front windshield. If the cables are adjusted to fix that, then there is not enough air sent to the floor and mid areas when switched to AC. There is plenty of heat, the problem seems to be something to do with perhaps the cables stretched or the air valves not wanting to open up fully when modes are switched. The cables are no longer available from Toyota. I have never taken the dash fully apart (and hope to avoid that). What is the best way to fix this? Any way to avoid taking the entire dash apart?

[NEC]

The heater control in the dash is known for breaking in our vans. it cracks and then flexes rather than moving the cables fully as it should. If you take out the heater control you should be able to repair/reinforce it with a few paperclips and some JB Weld at the broken areas. I think Toyota still sells these for around 100.00 but the liquid weld method is a stronger and better fix.

[timsrv]

The control unit you're talking about is NLA for 84-88 vans. 89 vans use a unique controller (non interchangeable) & I just purchased one about a month ago (it was one of only 2 remaining in US inventory). Like Mike said, none of the cables are available here in the US anymore. I'm not sure if these could be special ordered from Japan or not. If your cables are stiff, lubricate them and it will make a HUGE change in performance.

Motorcycle shops sell a special teflon lube for this purpose (comes in a spray can like wd-40). They also sell cable lubrication tools (for injecting the lubricant into the cable), but I've found plastic wrap to work well. Just put the little delivery tube (that comes with the lube) parallel with the inner cable, slide it right up to the outer sheath, then wrap tightly with plastic wrap to seal. Then just put the other end of the tube on the can of lube and spray until the lube starts dripping out from the other end. If you lube them up every couple of years they will never get stiff. Tim

[Omicronmike]

My control unit on the dash is not cracked (yet), but probably is flexing when trying to move the control cables to either extreme. Yes, the cables are stiff. I would like to try the lube method Tim suggests, but does that require access or disconnecting the other end of the cables? I have not figured out how to get to the other ends. Is the stiffness likely to be just the control cables themselves or can there be a problem with the air control valves, where ever they are located?

[timsrv]

The most common stiffness issue is with the temperature slider. That one runs 2 cables so it's twice as likely to bind up. You can get to the other end of both those cables pretty easy. One of them is under the front of the van going to the heater core flow valve and the other hooks up to a duct door lever right above the gas pedal.

It sounds like your trouble is with the bottom right slider though. I haven't had too much trouble with that one, so I haven't had the need to investigate it's location (at least not enough to remember). Your problem could very well be with the door it opens. I'd move the slider back and forth while listening and looking for movement under the dash. Once you find it, disconnect the cable and operate both independent of each other. At that point it should become apparent which part is giving you trouble. Tim

[Omicronmike]

Yes, you are correct-- the temp control cable always has problems first because it gets exposed to weather underneath the van. I have replaced that cable twice over the years. Yes, it is the other cable that appears to be the problem. I have not been able to figure out where that cable goes to and I do not hear a door opening, probably because it just opens it a crack. Normally that "crack" is enough for defrost except when there is humidity from melting snow with cold temps outside. Then I cannot see anything until the entire van is thoroughly heated. There is a Harley Davidson dealer nearby and I will check them for a cable lubricant like you mentioned and try that.