Whats wrong with my heater??

V

vkmultra

New member
Hey guys....winter is finally here in Montana and it's -2 degrees right now. My 89 4runner (V6) is not blowing hot air, kinda luke-warm. I'm not sure if this is a quick, do-it -myself fix or not.
The blower fan and all adjusting knobs work just fine, and the A/C even works well. Is there some sort of temperature adjustment? It does get warm enough to defrost the windows but no-where near hot.
I don't think it's just the cold weather as I have been noticing the lack of warmth as it's been getting colder this year. Any ideas?????
:thanks:
 
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You could also be low on coolant, or have an air bubble somewhere in the system. Check the coolant level. If level is good, then goto harbor freight and buy a mityvac, they're not much, and put a vacuum on the system at the radiator cap and try to dislodge the bubble.

Also what the last poster said.
 
First make sure your heater control valve is operational. Have someone sit in the truck and work the lever back and forth from cold to hot, while you watch the valve (near the firewall) to make sure it is opening and closing. If all checks out, remove the hoses and gently flush it. It might have some crud in there. Start easy before you take on a bear of a job like the heater core (which could be the culprit).
 
SDHNTR said:
First make sure your heater control valve is operational. Have someone sit in the truck and work the lever back and forth from cold to hot, while you watch the valve (near the firewall) to make sure it is opening and closing. If all checks out, remove the hoses and gently flush it. It might have some crud in there. Start easy before you take on a bear of a job like the heater core (which could be the culprit).
Click to expand...

Can someone post a picture of this heater control valve ??

I have the same problem :(
 
hjalti_gto said:
Can someone post a picture of this heater control valve ??

I have the same problem :(
Click to expand...

I believe (someone correct me if I'm wrong) it is the valve that is operated by the temperature control cable. It will be at intersection of hoses near the firewall that has a cable running to it.
 
99blackSE said:
I believe (someone correct me if I'm wrong) it is the valve that is operated by the temperature control cable. It will be at intersection of hoses near the firewall that has a cable running to it.
Click to expand...

It's easy to find. Look near the firewall where the heater hoses go through. If you have someone sitting in the truck moving the lever, you should easily see the cable moving.
 
Okay, here is the update...
Heater control valve is working fine...thanks for the first direction...:)
The other possible problems that I have been told is that:
1. there might be air in the system (gurgling sounds behind the dash..anyone know if it's connected?)
2. my thermostat needs to be replaced.

Regarding the air in the system, has anyone ever had success in burping air out of the radiator? I tried it yesterday, opened the radiator and started the car. I didn't see any air bubbles surface before shut it off. I only let it run for about 30 seconds because I got freaked out by the antifreeze pouring out the top. Attempt failed?

After driving around yesterday, the heat did start working better, in fact the hottest its been. Although it's still not getting hot enough. Also, I tried the rear heat for the first time and it blows nice and hot. Is this a separate system?:shrug:
 
vkmultra said:
Okay, here is the update...
Heater control valve is working fine...thanks for the first direction...:)
The other possible problems that I have been told is that:
1. there might be air in the system (gurgling sounds behind the dash..anyone know if it's connected?)
2. my thermostat needs to be replaced.

Regarding the air in the system, has anyone ever had success in burping air out of the radiator? I tried it yesterday, opened the radiator and started the car. I didn't see any air bubbles surface before shut it off. I only let it run for about 30 seconds because I got freaked out by the antifreeze pouring out the top. Attempt failed?

After driving around yesterday, the heat did start working better, in fact the hottest its been. Although it's still not getting hot enough. Also, I tried the rear heat for the first time and it blows nice and hot. Is this a separate system?:shrug:
Click to expand...

Rear heat is on its own...

Tip, if your having troubles getting the air out, jack the front end up. Run it with the rad cap on but lose. When the T-Stat opens it will gurgle and burp... Run it for a bit after. Shut the engine off let it sit/cool down. Top it up... Tighten cap, go for a drive.. Let it cool again and check the level.

Honestly sounds like you need to flush the front heater core, prob full of crud!
 
another possibility is the valve on airbox that controls air mixture might be sticking mine was doing same thing looked under dash where heater box is and found when lever is slid to full heat arm only moves 1/2 way moved it rest of way with my hand and wow did it get warm " just an idea"
 
Heater only works while driving

When I'm at a red light, my 4runner starts to blow luke warm air but when I'm driving, it pushes out heat. Same thing happens after 10 min of idling. Does anyone know why this happens?
 
Probably low coolant. Then wiggle all the hoses to get any air bubbles to move through. Air bubbles are not your friend. Had the same problem and adding coolant and determining that air will rise to the top of any loop in a hose, wiggling the hose and adding more coolant solved the problem.
 
papichyno said:
When I'm at a red light, my 4runner starts to blow luke warm air but when I'm driving, it pushes out heat. Same thing happens after 10 min of idling. Does anyone know why this happens?
Click to expand...

likely low coolant, as said above.

though, I HAVE seen a case where the fins on the water pump impeller actually disintegrated, and had the same symptoms. higher rpms would push the water, and give some heat, but not at an idle.
 

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nevada said:
likely low coolant, as said above.

though, I HAVE seen a case where the fins on the water pump impeller actually disintegrated, and had the same symptoms. higher rpms would push the water, and give some heat, but not at an idle.
Click to expand...


Thanks guys. I'll give you an update
 
Questions as well,

So I am having the same issue, and I've run through a few checks. Originally had the running water sound in the engine, and I've been keeping the fluid levels up, then had a working heater for like a week. Now it's back to the lukewarm from the front ones. The thermostat seems to work as it shows the correct engine temp, the tubes running to the heater valve are nice and hot, the valve opens and closes, and the back floor heater works quite well. That's as far as I've gotten, query as what to do next, seeing if people have had solutions.
 
COAKScottishrunner said:
So I am having the same issue, and I've run through a few checks. Originally had the running water sound in the engine, and I've been keeping the fluid levels up, then had a working heater for like a week. Now it's back to the lukewarm from the front ones. The thermostat seems to work as it shows the correct engine temp, the tubes running to the heater valve are nice and hot, the valve opens and closes, and the back floor heater works quite well. That's as far as I've gotten, query as what to do next, seeing if people have had solutions.
Click to expand...

maybe the blend door. lay under the dash and cycle the hot/cold controls. watch what moves, and doesn't move. it sounds like a control cable has popped off. I cant remember which side the blend door is on, there are controls on each side, so check them both.
 
I'm banking on a clogged core... for some reason I see so many issues with them in these trucks.

I made a super simple tool for about $5 at Home Depot and it works awesome. 10' roll of 5/8" clear vinyl tubing and one brass garden hose thread x hose barb fitting. Cut the hose into a 2' long pressure line and use the remaining 8' as a discharge so you don't get hosed. Hook up to heater core and let run full blast for a few minutes, then reverse the hoses and do it again.

You'd be surprised how much trash usually comes out...
 
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