MTL_4runner

Holy freakin heck........we started out on a road trip that ended in just pure hell. The 4runner seems to have "some" heat when you are going at lower speeds but when we were on the highway, the temp dropped so much inside I could see my breath (mind you it was -20 today...but my Civic still had super warm air) and the condensation on the windows froze!!! We rode for about 1.5 hours in the freezing cold (it got gradually worse and worse until we couldn't take it anymore) and we had to turn back and get the Honda instead (which was a huge relief after that little episode).

So all in all I have some (all be it very little) while moving slower speeds but at highway it is FRIGID!
I also tried every combination of recirculate, heat, defog, defrost to no avail.


1) Anyway I was wondering if anyone has had something like this happen on their 3rd gen and if so, what was it?


2) Also can someone post the section for the HVAC for a 96 4Runner from the FSM or Haynes (I wanted to study it on our trip to see if I can get a good idea of where to look to solve this problem)?

Mad Chemist

That's messed up, sounds like something else is going on. How did the engine temperature look? Maybe a blocked/partially plugged heater core? If the engine temp was normal, but you weren't getting heat inside, it would point to the heater core, right? If everything was operating fine, you could put carboard in front of the radiator to help keep the temperature of the engine up a bit, but it sounds like something else is not functioning properly.

mtnmuse

I'm assuming the outside air temperature was cold enough to cause your cabin temperature to drop so low, but the problem may be that your thermostat is stuck closed. I've had a similar thing happen with my 3rd gen and replacing the thermostat fixed the problem.

Very easy fix and doesn't cost much. If you're not familiar, the thermostat is located on the engine block at the connection for the bottom radiator hose. Be prepared to drain the coolant into a bucket. Pull the old therostat out, plug the new one in with the supplied gasket, refill the radiator and your heater should work again.

Good luck!

4RUNR

MTL_4runner, mine never got that cold, to see breath inside when it warmed up. I started a thread about the frost on the inside of the windows.

Easy test for the thermostat that I did few days ago using same thing you got, the Auterra. Do a test run and measure the coolant temperature. Mine surprisingly kept at roughly 192F at highway speeds. Same as it does in 90+ in the summer.

the_supernerd

Try checking your heater control valve. The cable might have broke and it could be stuck in the closed position.

MTL_4runner

Thanks for the replies guys!

Yeah it was the wierdest thing because the engine temp on the guage was exactly where you would expect it to be considering the temp was very low (readout was only very slightly lower than you'd see in the summer...so I considered it quite normal all things taken into account). So this leaves me with the assumption that very little coolant was making its way through the heater core (ie a heater control valve that was blocked, stuck or not moving properly) or that something in the ductwork was allowing massive amounts of cold air into the truck (I doubt this) or that the ducts were blocking off the heat and not letting air pass over the heater core (need to see the ducts layout to verify if this is a feasible scenario).

The true bizzare part was to have the engine temp normal and have a tiny bit of heat when going slow yet freezing when at highway speed.

I will refrain from taking it on long roadtrips for now and take it apart when temps are above 0 degrees.

Mad Chemist

You had the knob turned into the red zone, right?

02SE

I hope not, since it's a slider in '96-'97.