I've got a '92 Runner with rear heat, which does work, but nothing out of the front, it's been sporadic to say the least. Checked the heater core for blockage, did the thermostat, checked the HVAC cables and operated on the heater valve mounted on the firewall. I'm assuming the last culprit would be the water pump, although I haven't had any overheating problems and there's rear heat... Any ideas?? Thanks.

Fan under the dash is working, yes/no?

Fan works. temp control will adjust and blow cold, all vents work.....

Hmmm... I'm not finding a good wiring diagram for the heaters in a Runner. BUT-- am willing to bet the blower resistor is bad. Seems to me the rear heaters have their own elements. At least my '99 is set up that way.

The resistor is either behind your blower motor, or next to the AC unit near the AC and heater fuse block behind your glove box.

Go here

In the '96 FSM, go to the end of the FSM, then back up to page AC 36 or AC38, and you'll see the checkout for the blower resistor. At least that'll give you an idea of what you're looking for.

You can find them in a junkyard, or from the dealer for under $25.

If you still want a good schematic, for $10 for 24 hours you can download away at www.techinfo.toyota.com. The '93 FSM we have sticky'd over in the early trucks section doesn't have the resistor shown that I can find.

Hope that helps!

He said the blower motor works, so the blower resistor is OK.

Grab the coolant lines coming in and out of the heater core on the firewall. Are they both HOT?

I've had my blower work and no heat before too (my 86)- resistor fixed it.

I thought the blower resistor controlled the fan speeds, and if it goes out the fan doesnt work?

I figured that was the case too, but that's what I was workin' with.

To the poster, do as Adam suggested on checking the hoses; just cuz you replaced the t'stat doesn't mean it's a good one, esp if you didn't check it before installing.

Did this problem just come about or did you service the cooling system recently? You could have an air pocket. Jack the front of the truck up or park on an incline. Remove the radiator cap and run the truck up to temperature. Hopefully you will see some bubbling.

Problem just came up. I've cleared the system of any air locks, but still no luck. Both hoses do heat up when the engine gets up to temp. Is there any way to tell how well the water pump is working other than squeezing the top rad hose and feeling for a surge??