Heater in Toyota Corolla does not work

DBALLARD18

MEMBER
2002 TOYOTA 4RUNNER
4 CYL
144,000 MILES

2002 Toyota Corolla. Since we have owned the car for 3 years, the heater has never been 'great'. There is an occasional whistling sound in the air ductwork. The last 2 weeks, I replaced the water pump, thermostat and flushed the entire system as a PM move. THe car has 144,000 miles. The weather has turned cold in Ohio. The blower works. There is an instant of hot air and then just ambient (cold) air. The upper heater hose is hot, the lower hose is warm. I looked at the white levers for the duct door and they are moving and it 'sounds' like the door is moving when I move the **** fast to the end, I can "hear" it hit the stops. I think.

So the blower works, hoses are hot, and I see the lever to the door moving. Bit still have cold air.

8 Replies

KHLOW2008

MECHANIC
41,814 POSTS

You mentioned 4-Runner and Corolla, both are different vehicle. Which is the correct one?

Have you checked the air mix damper and vents?
The upper hose being hiot and lower hose only warm indicates the heater core could be clogged. Did you try back flushing it?

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Saturday, December 25th, 2010 AT 3:35 AM

DBALLARD18

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Sorry, I don't know where the 4 runner came from. It is a Corolla. I have flushed the heater core with the hoses being loose and have confirmed that the core is clear. And passes sufficient water.

The heater has never really worked well, i.E, blown a lot of hot air. Warm at best. 2 weeks ago I changed the water pump, thermostat, flushed the system including the heater core, and aded new anti-freeze. This was just a preventative maintenance as the car has 144,000 miles.

Now the weather is cold in Ohio. The heater is null and void.

The top heater hose is hot, the bottom hose is colder than the top. I have looked at the linkage to the heater door. The linkage is moving completely. I believe I can hear the door when I move the control **** and try to slam it shut. This is an I believe point, not a fact.

If I let the car warm up and leave the fan off, then turn the fan on, I get a quick spurt of hot air then. Cold air (or rather ambient air) from then on. The AC compressor is not on. The blower is working fine. The car warms up to the normal mid gage temperature.

I vented? The system this afternoon. I removed the top hose at the heater. Then I pointed the top hose vertically up so that it would be at a higher elevation than normal. I took a 2 foot piece of heater hose and a funnel, hooked it to the top heater connection. Then I poured antifreeze in the funnel with a 2 foot elevation into the top hose connection. This forced antifreeze through the heater core, the engine and back out the hose I had pulled loose. So unless there is a pocket of air I can't figure out, I think I vented the engine.

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Saturday, December 25th, 2010 AT 7:35 AM

KHLOW2008

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41,814 POSTS

Ensure the heater valve is not clogged. Though it opens and close, it could be clogged and not allowing oolant to pass. Fuly open it and use a hose to test if it is clogged.

To vent (bleed) the system, remove the radiator cap, turn heater to maximum and start engine. Run for about 5 minutes and top up coolant if necessary. Once coolant level in radiator stabilises, close radiator cap and test.

Check the air mix and mode control cables and adjust if necessary.

Set the temperature control dial at "MAX. COOL" position

Set the mode control dial at "DEF" position.

NOTE: Lock the clamp while lightly pulling the outer cable to the direction shown by arrow in the illustration.

Fig. 154: Adjusting Air Mix Control Cable

Adjust the air mix control cable.

Set the air mix damper control lever to "MAX. COOL" position and connect the inner cable to lever pin and clamp the outer cable.

NOTE: Lock the clamp while lightly pushing the outer cable to
the direction shown by arrow in the illustration.

Fig. 155: Adjusting Mode Control Cable

Adjust the mode control cable: Pull the air inlet control link to "DEF" position and connect the control cable and lock the clamp.

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Saturday, December 25th, 2010 AT 9:04 AM

DBALLARD18

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I have not located a heater control valve. Does this model have one?

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Saturday, December 25th, 2010 AT 1:53 PM

DBALLARD18

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I have completely pulled the hoses from thee heater and the thermostat. All lines are fully clear, used a water hose, and flushed and backflushed the heater core. No problems there.

I removed the console and glove box. The heater control cable operates the damper properly, as viewed from the outside.

BEyond that. If the damper actually works, is there a way that some plastic could have gotten pulled in and is laying up against the heater fins?

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Saturday, December 25th, 2010 AT 4:36 PM

KHLOW2008

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I could not find any indication of a heater control valve so it should not be equipped with one.

The air mix control cable and the door it operates is the main item related with poo r heating efficiency. If the door is leaking, heat would be insufficienty. So would clogged fins of the heater core result in poor heating.

If air volumn decresaes when heater is turned on, it could mean the fins are clogged. This would require the heater core to be removed for inspection/repair.

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Saturday, December 25th, 2010 AT 5:10 PM

DBALLARD18

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I believe this is the last question. The heater doors all operate from the outside as they should. I have flushed the engine, all hoses and the heater using a garden hose with all of the hoses disconnected and the water ouring on the ground. The heater has good flow when I use a garden hose.

I filled the engine with antifreeze. Then I worked to be sure all of the air was out of the engine. I poured water through a long funnel to each of the heater hoses, which were disconected to get all air bubbles out, as evidenced by water being pushed through the radiator fill cap. Then I hooked the funnel up to a heater tip using a 2 foot length of hose and then the funnel, so I had a good 2+ foot of head pressure. Both hoses were off of the heater at this time. I filled the funnel wanting to be sure that I could push water through the heater and air out. With only the 2 foot of heat pressure, there was VERY little water being pushed through the heater.

Since I have eliminated the engine and hoses, and the doors, I can only arrive at a stopped up heater core. WOuld this be your conclusion as well? Thank you for your time, and Merry Christmas.

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Saturday, December 25th, 2010 AT 7:19 PM

KHLOW2008

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The system has to be bled of air an I had described the procedure in one of the previous post.

Yes, I would concur with you on the problem being with the heater core. It could be the blend door but that would require removal of the heater core to check.

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Sunday, December 26th, 2010 AT 10:38 AM