[hokemon]

So after reading past posts and going crazy over my car not having heat (I only now realized as it is getting cold in PA early in the AM) a light bulb came on to try my rear, seperately controlled heat. That comes out super hot, but up front, nothing. (I also have condensation dripping on the passenger side of my floor - since I've bought it - so everyone said heater core, until i let it drip in a glass and realized it was H20).

So... any ideas on what the problem is and how do I start to fix it? No heat in the front, but the lower floor heating which is seperately controlled in the rear works fine and other than that everything in the car is a go. (Blows out full blast, just cold)

2001 4runner SR5

Thanks!

[badattitude]

You may have two issues. I still think front heater core makes sence. The h20 may be due to a clogged drian.

Find the silver condencer drain on the passenger side right above the tie rod. If you have compressed air try blowing it up the drian tube to clear any blockage. if you don;t have compressed air an long pipe cleaner or wire could be used. The idea is to make sure the condensation can drain. I belive a clogged drian is your isse with the H20 in the cab. That should fix the condensation drip. If it does and the front heat is still broke a new front heater core is next up.

The nice thing is the trouble shooting on the condensation is free.

[YotaZach85]

I would start with clearing the condensate drain that comes through the fire wall, they get clogged and will run over and drip on the floor. If it were a bad heater core it would be coolant leaking to the floor. It sounds to me that your switching valve isn't working. I would change it from cold to hot and see if the valve on the fire wall opens or not. If not, for a temporary fix, you can manually open the valve to get some coolant flowing through the front heater core.

[hokemon]

Originally Posted by YotaZach85

I would start with clearing the condensate drain that comes through the fire wall, they get clogged and will run over and drip on the floor. If it were a bad heater core it would be coolant leaking to the floor. It sounds to me that your switching valve isn't working. I would change it from cold to hot and see if the valve on the fire wall opens or not. If not, for a temporary fix, you can manually open the valve to get some coolant flowing through the front heater core.

Thank you for the response! Is there a picture or direction to this said switching valve?

[YotaZach85]

Originally Posted by hokemon

Thank you for the response! Is there a picture or direction to this said switching valve?

I don't have any pictures but if you follow the heater hoses where they enter the cab through the fire wall you'll see a black box with a leaver on 1 of them. That's actually what controls hot and cold, all the way cold = valve closed and all the way hot = valve open. I'm not sure what switches the valve on your model but I've heard of them going bad and it being a little on the exspensive side to replace.

[BOSSIND]

Wondering if this has been resolved as I'm having the same issue. I've checked the valve and its opening and indeed allowing hot coolant into the heater core so i suspect a flap isn't working to allow air through the heater core, I can get a little bit of heat to the passenger floor, but non to the ducts or the defrost. The servos are moving of the ones I can see, not sure if there is another.

Also wanted to add to the original poster, regardless of a leaking heater core you should still have heat unless of course you have lost so much coolant it no longer flows through the core - so I doubt the core is the issue.

[steanson]

Curious about this old post as well as the last comment.

My woes started 2 years ago, no heat. I figured a clogged heater core, so one day I decided to put a garden hose with nozzle to the heat/cold valve on the firewall...and discovered NO coolant flowing through this valve. as I crammed the nozzle on the hose fitting, IT CRUMBLED. DANGIT!

I would drive it until it began to leak, as I shoved the hose back on as best as possible...and for 2 years, NOTHING. Until a week ago...I blew a heater hose/coolant hose on the firewall...it just blew OFF, not a hole in the hose. I put it back on with a second hose clamp. 100° Texas Summer heat...well, the MAIN radiator hose blew off the next day I drove to work (15 minutes hwy driving, blew as I exited)...same thing, just blew off the radiator, wasn't destroyed.

I decided to flush the radiator and system, but remembering I have no heat and no flow, it dawned on me that there is heat in the back; lo and behold, HOT HEAT in the back seat (this would have been welcome last winter).
DOES ANYBODY HAVE A CLUE AS TO WHAT IS GOING ON HERE???
Two heater cores?

I am thinking it could simply be a thermostat for my overheating issues, but the heater core thing baffles me. The hot/cold valve not having coolant flowing through it explains why there is no heat, but how is the back heat working? Where else would there be a CLOG that is restricting coolant flow through that valve on the firewall?

[BOSSIND]

Mine turned out to be a flap in the heater box that wouldn't move, bought a used heater box and replaced it. Huge job.

[TheDurk]

Originally Posted by steanson

Curious about this old post as well as the last comment.

My woes started 2 years ago, no heat. I figured a clogged heater core, so one day I decided to put a garden hose with nozzle to the heat/cold valve on the firewall...and discovered NO coolant flowing through this valve. as I crammed the nozzle on the hose fitting, IT CRUMBLED. DANGIT!

I would drive it until it began to leak, as I shoved the hose back on as best as possible...and for 2 years, NOTHING. Until a week ago...I blew a heater hose/coolant hose on the firewall...it just blew OFF, not a hole in the hose. I put it back on with a second hose clamp. 100° Texas Summer heat...well, the MAIN radiator hose blew off the next day I drove to work (15 minutes hwy driving, blew as I exited)...same thing, just blew off the radiator, wasn't destroyed.

I decided to flush the radiator and system, but remembering I have no heat and no flow, it dawned on me that there is heat in the back; lo and behold, HOT HEAT in the back seat (this would have been welcome last winter).
DOES ANYBODY HAVE A CLUE AS TO WHAT IS GOING ON HERE???
Two heater cores?

I am thinking it could simply be a thermostat for my overheating issues, but the heater core thing baffles me. The hot/cold valve not having coolant flowing through it explains why there is no heat, but how is the back heat working? Where else would there be a CLOG that is restricting coolant flow through that valve on the firewall?

The rear heat has its own core and its own valve. Hot coolant flows through tubes from the engine directly to the mini core. Rear heater takes air from under the passenger seat and blows it out the rear corner of the center console.

Sounds like you need an overhaul of your cooling system. Flush radiator and front and rear cores, check for good flow through all three. Verify heater valve. Replace every hose and clamp you can get to.

[Tkeeling]

I got a 1998 3.4L v6 limited 4 runner the heat up front blows warm but got no heat in the back at all need help finding out how to fix this

[brillo_76]

Originally Posted by Tkeeling

I got a 1998 3.4L v6 limited 4 runner the heat up front blows warm but got no heat in the back at all need help finding out how to fix this

Is the rear heater lines hooked up? If they are all that left is the rear heater controls and fan in the rear. Lots of 1996 to 2000 were disconnected because the lines were steel and rusted through.

Sent from my SM-A536V using Tapatalk

[Romeo1]

Originally Posted by Tkeeling

I got a 1998 3.4L v6 limited 4 runner the heat up front blows warm but got no heat in the back at all need help finding out how to fix this

Your heater cores are most likely plugged up. Both of my heater cores were. The OTC 6043 tool is a power flush gun that lets you flush everything forward and reverse. Once the system is completely base lined, I can make sure it stays corrosion free.

Best $53 spent on a cooling service tool evar. I’m sure it costs more now.

You could probably do it other ways also. Garden hose or air if on a budget. The take home message is that your cores are plugged from corrosion and garbage from the arguably poor design of a high placement heater valve and radiators that seem to die while owners number one through three don’t address them properly.

Odds are the hose nipples on your water heater valves shut off are junk also.

Tim the tool man also has a good video on the process. Cooling System Flush - YouTube